CRLF Injection and Log Poisoning are security flaws that can confuse system logs, making it hard to trust the information they contain.
CRLF stands for Carriage Return (CR) and Line Feed (LF), which are special characters used to create a new line in text. When an attacker can control input, they can insert these characters into logs, which might create fake log entries or mislead administrators. This is called Log Poisoning. In a log poisoning attack, attackers can insert false log entries, hide their actions, or manipulate logs to confuse system administrators. This makes it harder to detect issues or track malicious activity.
CRLF injection vulnerabilities occur when an application fails to properly handle user input. If user data is logged directly without proper checks, attackers can inject CRLF characters, causing problems like:
To prevent CRLF injection and log poisoning, it’s important to properly sanitize and validate any user input before it’s logged. Below are some solutions to fix this issue: