HTTP Response Splitting

HTTP Response Splitting

HTTP response splitting is a type of web application vulnerability that can be exploited by an attacker to inject malicious code into a website. It occurs when an attacker is able to manipulate the web server’s response to their request. This can be done by inserting additional headers, modifying existing headers, or injecting malicious code into the response body.

HTTP response splitting is a serious vulnerability because it can be used to inject malicious code into a website and potentially gain control of the server. It can also be used to launch other types of attacks, such as cross-site scripting (XSS) and SQL injection.

What is HTTP Response Splitting?

HTTP response splitting occurs when an attacker is able to manipulate the web server’s response to their request. This can be done by inserting additional headers, modifying existing headers, or injecting malicious code into the response body.

For example, an attacker might send a request with a maliciously crafted URL that contains a carriage return line feed (CRLF) character. This character is used to indicate the end of a line in a text file. When the web server receives this request, it will interpret the CRLF as a new line and will process the malicious code as if it were a legitimate request.

How Does HTTP Response Splitting Work?

When an attacker sends a maliciously crafted request to a web server, the web server will interpret the CRLF characters as a new line and will process the malicious code as if it were a legitimate request. The attacker can then use this to inject malicious code into the response body or modify existing headers.

The malicious code could then be used to gain control of the web server, launch other types of attacks, or to steal sensitive information.

Example HTTP Response Splitting Payload

https://victim_target.com/path/to/resource?page=foobar%0d%0aContentLength:%200%0d%0d%0a%0aHTTP/1.1%20200%20OK%0d %0aContent-Type:%20text/html%0d%0a%20Content-Length:%2019%0d%0a%0d%0aAttack

How To Prevent HTTP Response Splitting

There are several steps that can be taken to prevent HTTP response splitting.

• Validate user input: All user input should be validated to ensure that it does not contain any malicious code. This includes input from URL parameters, form fields, and cookies.

• Use a web application firewall (WAF): A web application firewall (WAF) can be used to detect and block malicious requests.

• Use secure coding practices: Secure coding practices should be used to ensure that applications are properly sanitizing user input.

• Monitor for suspicious activity: Regularly monitor for suspicious activity, such as requests with malicious headers or code injections.

Conclusion

HTTP response splitting is a serious vulnerability that can be used to inject malicious code into a website and potentially gain control of the server. It can also be used to launch other types of attacks, such as cross-site scripting (XSS) and SQL injection.

To prevent HTTP response splitting, organizations should validate user input, use a web application firewall (WAF), use secure coding practices, and monitor for suspicious activity. By taking these steps, organizations can help protect their websites and applications from HTTP response splitting attacks.