Cross-site tracing (XST) vulnerability

Sooraj V Nair
Published on
11 Dec 2023
6 min read

A Cross-Site Tracing (XST) attack involves the use of cross-site Scripting (XSS). It uses the TRACE or TRACK HTTP methods which allow the client to see what is being received at the other end of the request chain. It is then used for testing or diagnostic information.

The TRACK HTTP method is only applicable to Microsoft’s IIS web server whereas XST could be used as a method to steal users’ cookies via XSS.

This will work even if the cookie has the “HttpOnly” flag set and/or exposes the user’s authorization header.

This site also allows an attacker to inject malicious code into the link and implement the HTTP TRACE method. Also, the attacker can even steal the user’s cookies via XSS.

Example of cross site tracing

curl -X TRACE

User-Agent: curl/7.24.0 (x86_64-apple-darwin 12.0) libcurl/7.24.0 OpenSSL/0.9.8r zlib/1.2.5
Accept: */*

How can cross-site tracing vulnerability be exploited?

If the TRACE method is enabled without proper safeguards, it can potentially be exploited by attackers to conduct XST attacks. Here’s how the vulnerability works:

1. Exploitation

An attacker tricks a victim into making a request to a vulnerable web application that supports the TRACE method. This request includes malicious content, such as a script or injected code.

2. Reflective response

The web server processes the request and reflects the request headers in the response body, as per the TRACE method’s behavior.

This response includes the malicious content provided by the attacker.

3. Script execution

The attacker’s malicious content is now executed in the context of the victim’s browser. This can lead to various forms of attacks, including XSS attacks.

Cross-site tracing can be used as a vector to exploit other vulnerabilities or launch attacks that steal user credentials, perform actions on behalf of the victim, or manipulate the victim’s interactions with the web application.

What are the impacts of cross- site tracing vulnerabilities?

Cross-site tracing (XST) vulnerabilities can have significant impacts on both web applications and users. When successfully exploited, XST attacks can lead to various security risks and compromises.

Here are some of the potential impacts of cross-site tracing:

1. Cross-site scripting (XSS) attacks

XST can be used as an attack vector to execute malicious scripts in the victim’s browser.

This can result in Cross-Site Scripting (XSS) attacks, where attackers can steal sensitive user data, such as cookies or session tokens, manipulate the appearance and behavior of web pages, and perform actions on behalf of the victim.

2. Session hijacking and impersonation

By stealing session cookies through XSS attacks, attackers can hijack user sessions and impersonate legitimate users.

This allows them to access unauthorized areas of the application and perform actions on behalf of the victim.

3. Data breach

XST can lead to the theft of sensitive data stored in the victim’s browser, such as passwords, credit card information, and personal details.

Attackers can then use this stolen information for malicious purposes.

4. Data corruption

An attacker can use XST to manipulate data displayed to the user.

This could involve modifying the content of web pages, changing account settings, or altering data submitted to the server.

5. Privacy violation

XST attacks can expose sensitive information to unauthorized parties, violating user privacy and potentially leading to identity theft or other forms of fraud.

6. Application vulnerabilities

Successful exploitation of XST can indicate potential underlying vulnerabilities in the web application’s code, configuration, or security controls.

Addressing these vulnerabilities is essential to prevent further exploitation.

7. Compromised user trust

If users experience attacks through XST vulnerabilities on a website, their trust in the website’s security and integrity can be eroded.

This can lead to decreased user engagement and potential loss of business.

8. Financial loss

XST attacks can lead to financial losses for both users and organizations.

Users may suffer financial harm due to stolen payment information, while organizations may incur costs related to incident response, legal actions, and remediation efforts.

How can you prevent XST attack?

To prevent or mitigate cross-site tracing (XST) attacks, it’s important to implement a combination of technical measures, secure coding practices, and ongoing monitoring.

Here are some prevention and mitigation strategies:

1. Disable TRACE method

Disable the TRACE HTTP method on the web server if it is not necessary for your application’s functionality.

Configure the server or web application to reject TRACE requests.

2. Input validation and output encoding

Implement strong input validation to ensure that user input is properly sanitized and validated before being processed.

Use output encoding to prevent malicious content from being executed in the browser.

3. Security headers

Implement security headers such as X-XSS-Protection, Content-Security-Policy, and X-Frame-Options to mitigate the risk of various attacks, including XSS.

4. Web Application Firewall (WAF)

Utilize WAF to filter and block malicious requests, including those attempting to exploit XST vulnerabilities.

5. Regular security testing

Conduct regular security assessments, including vulnerability scanning and penetration testing, to identify and address potential vulnerabilities, including XST vulnerabilities.

6. Secure coding practices

Educate developers about secure coding practices and the risks associated with XST vulnerabilities.

Implement coding guidelines that emphasize input validation, output encoding, and proper handling of user data.

7. HTTP methods configuration

Review and restrict unnecessary HTTP methods beyond TRACE to minimize potential attack vectors.

8. Security awareness training

Regularly train and raise awareness among your development team about common security vulnerabilities and attack vectors.

Remember that security is an ongoing process, and it’s important to continuously evaluate and update your defenses against evolving threats.

By taking a proactive and multi-layered approach, you can significantly reduce the risk of XST attacks and enhance the overall security of your web applications.

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Written by
Sooraj V Nair
Sooraj V Nair
Cyber Security Engineer
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