CVE-2018-20835 : What You Need to Know

A weakness has been discovered in tar-fs before version 1.16.2, leading to an Arbitrary File Overwrite problem during the extraction of a tarball. This vulnerability allows the content of a plain file to overwrite an existing file in the system.

Understanding CVE-2018-20835

This CVE identifies a specific vulnerability in the tar-fs software.

What is CVE-2018-20835?

The vulnerability in tar-fs before version 1.16.2 allows an attacker to overwrite existing files in the system during the extraction process of a tarball.

The Impact of CVE-2018-20835

The vulnerability can result in unauthorized modification of files, potentially leading to data loss or manipulation.

Technical Details of CVE-2018-20835

This section provides more technical insights into the CVE.

Vulnerability Description

The weakness in tar-fs arises when extracting a tarball with a hardlink to an existing file, followed by a plain file with the same name as the hardlink. The content of the plain file replaces the content of the preexisting file.

Affected Systems and Versions

Affected Version: tar-fs before 1.16.2
Systems using tar-fs prior to version 1.16.2 are vulnerable to this exploit.

Exploitation Mechanism

The vulnerability occurs during the extraction of a tarball containing a hardlink to an existing file, combined with a subsequent plain file sharing the same name as the hardlink. This allows the content of the plain file to overwrite the content of the preexisting file.

Mitigation and Prevention

Protecting systems from CVE-2018-20835 requires specific actions.

Immediate Steps to Take

Update tar-fs to version 1.16.2 or newer to mitigate the vulnerability.
Avoid extracting tarballs from untrusted sources.

Long-Term Security Practices

Regularly update software and libraries to the latest versions.
Implement file integrity monitoring to detect unauthorized changes.

Patching and Updates

Apply patches provided by the software vendor promptly to address known vulnerabilities.