CVE-2018-20251 Explained : Impact and Mitigation

A vulnerability related to path traversal exists in WinRAR versions 5.61 and earlier, allowing attackers to create empty files and folders throughout the file system.

Understanding CVE-2018-20251

This CVE involves a path traversal vulnerability in WinRAR versions prior to and including 5.61, enabling malicious actors to manipulate the extraction process to create empty files and folders.

What is CVE-2018-20251?

In WinRAR versions 5.61 and earlier, a flaw in the filename field of the ACE format allows attackers to bypass the WinRAR validator's detection of traversal attempts. This results in the creation of empty files and folders across the file system during the extraction process.

The Impact of CVE-2018-20251

The vulnerability in WinRAR versions 5.61 and earlier poses a significant security risk as it enables attackers to manipulate the extraction process and create empty files and folders throughout the entire file system.

Technical Details of CVE-2018-20251

This section provides detailed technical insights into the vulnerability.

Vulnerability Description

The path traversal vulnerability in WinRAR versions prior to and including 5.61 allows attackers to exploit the filename field of the ACE format to create empty files and folders during the extraction process.

Affected Systems and Versions

Product: WinRAR
Vendor: Check Point Software Technologies Ltd.
Affected Versions: All versions prior to and including 5.61

Exploitation Mechanism

Attackers manipulate the filename field of the ACE format to bypass the WinRAR validator's detection of traversal attempts.
The UNACE module proceeds to create empty files and folders based on the contents of the filename field.
The extraction process is aborted after the creation of folders and files but before their contents are written.

Mitigation and Prevention

Protecting systems from CVE-2018-20251 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update WinRAR to a version beyond 5.61 to mitigate the vulnerability.
Exercise caution when extracting files from untrusted sources.

Long-Term Security Practices

Regularly update software and security patches to prevent exploitation of known vulnerabilities.
Implement file integrity monitoring to detect unauthorized changes to the file system.

Patching and Updates

Check for and apply the latest WinRAR updates to address the path traversal vulnerability.