Generic CRLF injection Vulnerability Fuzzer
In a CRLF injection vulnerability attack the attacker inserts both the carriage return and linefeed characters into user input to trick the server, the web application or the user into thinking that an object is terminated and another one has started. As such the CRLF sequences are not malicious characters, however they can be used for malicious intend, for HTTP response splitting etc.
Short Info
Level
Low
Single Scan
Single Scan
Can be used by
Asset Owner
Estimated Time
15 seconds
Time Interval
3 days
Scan only one
URL
Toolbox
-
Vulnerability Overview:
Vulnerability: CRLF Injection
Detection Method: CRLF Injection Detection
Impact: Improperly sanitized CRLF sequences can allow attackers to inject arbitrary HTTP headers or split responses, potentially leading to security breaches such as session hijacking, cross-site scripting (XSS), and cache poisoning.
Vulnerability Details:
A CRLF injection attack is one of several types of injection attacks. It can be used to escalate to more malicious attacks such as Cross-site Scripting (XSS), page injection, web cache poisoning, cache-based defacement, and more. A CRLF injection vulnerability exists if an attacker can inject the CRLF characters into a web application, for example using a user input form or an HTTP request. The CRLF abbreviation refers to Carriage Return and Line Feed. CR and LF are special characters (ASCII 13 and 10 respectively, also referred to as \r\n) that are used to signify the End of Line (EOL). The CRLF sequence is used in operating systems including Windows (but not Linux/UNIX) and Internet protocols including HTTP. There are two most common uses of CRLF injection attacks: log poisoning and HTTP response splitting. In the first case, the attacker falsifies log file entries by inserting an end of a line and an extra line. This can be used to hide other attacks or to confuse system administrators. In the second case, CRLF injection is used to add HTTP headers to the HTTP response and, for example, perform an XSS attack that leads to information disclosure. A similar technique, called Email Header Injection, may be used to add SMTP headers to emails.
The scanner tests for CRLF injection vulnerabilities by attempting to inject CRLF sequences (%0D%0A) along with other control characters and encodings into URLs and observing the responses. If the application processes these inputs without proper sanitization, it may echo the injected sequences in the response headers or content, indicating a vulnerability. This flaw can be exploited in various ways, depending on the application's behavior and the attacker's goals.
The Importance of Addressing CRLF Injection:
Although initially assessed as low severity, the potential impact of CRLF injection vulnerabilities can be significant, compromising the security and integrity of web applications. It's crucial to identify and remediate these vulnerabilities to protect against sophisticated attacks that exploit improper input handling.
Why S4E?
S4E offers the CRLF Injection Detection Scanner as part of our suite of security tools, designed to help organizations proactively identify and mitigate vulnerabilities in their web applications. Our comprehensive scanning technology, combined with expert guidance, ensures effective vulnerability management and enhanced security posture.
