CVE-2018-6334 : Exploit Details and Defense Strategies

A vulnerability in HHVM versions prior to 3.25.2 could allow for unexpected behavior due to multipart-file uploads.

Understanding CVE-2018-6334

This CVE involves a variable extraction error in HHVM, potentially leading to unanticipated outcomes when variables are not explicitly declared.

What is CVE-2018-6334?

The issue arises from multipart-file uploads causing variables to be inaccurately registered in the global scope, impacting versions of HHVM before 3.25.2.

The Impact of CVE-2018-6334

The vulnerability could result in unexpected behavior in scenarios where variables are used without prior declaration, affecting the integrity and security of the system.

Technical Details of CVE-2018-6334

This section delves into the specifics of the vulnerability.

Vulnerability Description

The problem stems from multipart-file uploads incorrectly registering variables globally, potentially leading to unpredictable behavior.

Affected Systems and Versions

Product: HHVM
Vendor: Facebook
Affected Versions: 3.25.2, 3.25.0, 3.24.6, 3.22.0, 3.21.10, and earlier custom versions

Exploitation Mechanism

The vulnerability can be exploited by manipulating multipart-file uploads to improperly register variables, exploiting the global scope vulnerability.

Mitigation and Prevention

Protective measures to address and prevent the CVE.

Immediate Steps to Take

Apply the official patch provided by Facebook for HHVM version 3.25.2.
Avoid using multipart-file uploads until the system is patched.

Long-Term Security Practices

Regularly update HHVM to the latest version to ensure all security patches are applied.
Implement secure coding practices to prevent similar vulnerabilities in the future.

Patching and Updates

Facebook has released a patch for HHVM version 3.25.2 to address this vulnerability.