HTTP Request Smuggling

Summary

HTTP Request Smuggling is a web application attack technique that exploits inconsistencies in the way HTTP requests are processed by different servers or intermediaries, allowing attackers to bypass security controls, manipulate requests, and potentially gain unauthorized access or execute malicious actions.

Key Characteristics

• Targets discrepancies between front-end and back-end HTTP request parsing.
• Exploits ambiguous Content-Length and Transfer-Encoding headers.
• Can lead to request hijacking, cache poisoning, and session fixation.
• Often used to bypass firewalls, load balancers, and security filters.
• Requires detailed knowledge of server and proxy configurations.

Defensive Controls

• Implement strict and consistent HTTP request parsing across all components.
• Disable or correctly configure conflicting HTTP headers like Transfer-Encoding and Content-Length.
• Keep web servers, proxies, and load balancers updated with security patches.
• Use web application firewalls (WAFs) capable of detecting request smuggling patterns.
• Perform regular security testing and code reviews to identify vulnerabilities.

Related Security Solutions

Web Application Firewalls (WAFs), Intrusion Detection and Prevention Systems (IDPS), secure proxy servers, HTTP protocol analyzers, and vulnerability scanning tools are commonly used to detect and mitigate HTTP Request Smuggling attacks.