CVE-2017-16821 Explained : Impact and Mitigation

Symphony 2.2.0, also known as b3log Symphony, contains a cross-site scripting (XSS) vulnerability in the admin console. This vulnerability can be exploited by supplying a manipulated X-Forwarded-For HTTP header, which is not handled correctly when displaying a client's IP address in the /admin/user/userid section.

Understanding CVE-2017-16821

b3log Symphony (aka Sym) 2.2.0 has XSS in processor/AdminProcessor.java in the admin console, as demonstrated by a crafted X-Forwarded-For HTTP header that is mishandled during the display of a client IP address in /admin/user/userid.

What is CVE-2017-16821?

CVE-2017-16821 is a cross-site scripting (XSS) vulnerability found in Symphony 2.2.0, also known as b3log Symphony, specifically in the admin console. This vulnerability allows attackers to execute malicious scripts in a victim's browser.

The Impact of CVE-2017-16821

Attackers can exploit this vulnerability to perform various malicious actions, such as stealing sensitive information, session hijacking, or defacing websites.
Users interacting with the affected admin console may unknowingly trigger the execution of malicious scripts, compromising their data and security.

Technical Details of CVE-2017-16821

b3log Symphony 2.2.0 is susceptible to the following:

Vulnerability Description

The XSS vulnerability resides in the admin console, particularly in the AdminProcessor.java file.
It occurs due to mishandling of a crafted X-Forwarded-For HTTP header when displaying a client's IP address in the /admin/user/userid section.

Affected Systems and Versions

Product: Symphony 2.2.0 (b3log Symphony)
Vendor: N/A
Version: N/A

Exploitation Mechanism

Attackers can exploit this vulnerability by supplying a manipulated X-Forwarded-For HTTP header, which the system fails to handle correctly, leading to the execution of malicious scripts.

Mitigation and Prevention

It is crucial to take immediate steps to mitigate the risks posed by CVE-2017-16821:

Immediate Steps to Take

Disable or restrict access to the admin console until a patch is available.
Implement input validation mechanisms to sanitize user-supplied data and prevent XSS attacks.

Long-Term Security Practices

Regularly update and patch the Symphony software to address security vulnerabilities promptly.
Educate users and administrators about the risks of XSS attacks and best practices for secure web application development.

Patching and Updates

Stay informed about security updates and patches released by the Symphony project.
Apply patches as soon as they are available to protect systems from known vulnerabilities.