CVE-2018-14773 : Security Advisory and Response

A vulnerability has been identified in the Http Foundation component of Symfony versions 2.7.0 to 2.7.48, 2.8.0 to 2.8.43, 3.3.0 to 3.3.17, 3.4.0 to 3.4.13, 4.0.0 to 4.0.13, and 4.1.0 to 4.1.2. This vulnerability allows users to manipulate the request URL path through specific HTTP headers, potentially leading to exploitation.

Understanding CVE-2018-14773

This CVE pertains to a security issue in Symfony versions that could be exploited by malicious actors to override the path in the request URL.

What is CVE-2018-14773?

The vulnerability arises from the inclusion of a legacy IIS header that permits users to alter the path in the request URL using certain HTTP headers, even if the server is not running IIS. This oversight enables attackers to exploit the affected function in Symfony's Http Foundation component.

The Impact of CVE-2018-14773

The vulnerability allows unauthorized users to manipulate the request URL path, potentially leading to attacks such as web cache poisoning. This could compromise the integrity and security of Symfony applications.

Technical Details of CVE-2018-14773

This section provides detailed technical insights into the vulnerability.

Vulnerability Description

The issue stems from the support for a legacy IIS header that enables users to override the request URL path through specific HTTP headers, regardless of the server running IIS. The affected function is \Symfony\Component\HttpFoundation\Request::prepareRequestUri().

Affected Systems and Versions

Symfony versions 2.7.0 to 2.7.48
Symfony versions 2.8.0 to 2.8.43
Symfony versions 3.3.0 to 3.3.17
Symfony versions 3.4.0 to 3.4.13
Symfony versions 4.0.0 to 4.0.13
Symfony versions 4.1.0 to 4.1.2

Exploitation Mechanism

Attackers can exploit this vulnerability by sending crafted requests with specific HTTP headers (X-Original-URL or X-Rewrite-URL) to Symfony applications, allowing them to manipulate the request URL path.

Mitigation and Prevention

Protecting systems from CVE-2018-14773 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply the security update provided by Symfony promptly.
Monitor and restrict HTTP headers that can be used to manipulate request URLs.

Long-Term Security Practices

Regularly update Symfony and other dependencies to mitigate potential vulnerabilities.
Implement strict input validation to prevent unauthorized manipulation of request data.

Patching and Updates

Ensure that the Symfony framework is updated to a patched version that removes support for the vulnerable HTTP headers.