CRLF Injection

CRLF (Carriage Return Line Feed) Injection is a sophisticated exploitation technique in the Payload Execution phase where an attacker injects CR and LF characters (represented as %0D%0A in URL encoding) to manipulate HTTP requests or server logs. During the Injection Exploitation stage, attackers leverage these special characters to trick applications into interpreting the injected sequence as legitimate line terminators, potentially enabling HTTP response splitting, header manipulation, log forgery, or cross-site scripting (XSS). This technique can lead to serious security breaches as it allows attackers to bypass input validation mechanisms, modify HTTP headers, inject malicious content into application responses, or poison web cache systems. The exploitation occurs when applications fail to properly sanitize user inputs that are subsequently used in HTTP headers or written to log files, creating opportunities for attackers to execute unauthorized code, steal session tokens, or conduct other attacks that facilitate deeper system penetration.