> For the complete documentation index, see [llms.txt](https://appsecexplained.gitbook.io/appsecexplained/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://appsecexplained.gitbook.io/appsecexplained/bypassing-controls/waf-bypasses.md).

# WAF Bypasses

**Encoding Evasion**: Use URL, Unicode, Base64, or other encodings to disguise payloads.

**HTTP Parameter Pollution**: Manipulate parameters to exploit the way the WAF processes multi-instance parameters. (One of my favourite techniques!)

**Session Splicing**: Divide the attack into multiple requests or sessions to disrupt the WAF's ability to correlate the events.

**Verb Tampering**: Change the HTTP method (GET, POST, HEAD, etc.) to an unconventional one that the WAF might not inspect.

**Path Obfuscation**: Include irrelevant path information that gets ignored by the server but confuses the WAF (like using directory traversal techniques).

**Query String Manipulation**: Alter the query string with special characters or payloads that might be overlooked by the WAF.

**Header Manipulation**: Modify HTTP headers such as `User-Agent`, `Referer`, or custom headers in ways that are not expected.

**Cookie Poisoning**: Inject payloads into cookie values which may not be inspected or properly sanitized by the WAF.

**Content-Type Evasion**: Use unusual or mismatched content-types in the HTTP header to bypass checks that are content-type specific.

**Extension Manipulation**: Changing file extensions or using obscure ones to evade filters that inspect file names.

**Protocol-Level Evasion**: Utilize discrepancies in protocol implementations (like ambiguous requests) that may be differently interpreted by the WAF and the target web server.

**Attack Obfuscation with Legitimate Requests**: Mix in legitimate traffic with the attack traffic to reduce the anomaly score that might otherwise trigger the WAF.

**Bypassing with JavaScript**: Use JavaScript to construct the final payload in the client-side browser, which may not be executed or recognized by the WAF.

**Using Comment Injection**: Place comments within SQL statements or scripts to disrupt signature detection.

**Utilizing Server-Side Request Forgery (SSRF)**: Exploit the server's functionality to make requests that bypass the WAF's rules.

**Timing Attacks**: Execute actions with delays, leveraging the fact that some WAFs have a time window for rule execution.

**Ruleset Flaws**: Exploit known weaknesses in the rulesets employed by popular WAFs, which are sometimes documented by security researchers.


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