CVE-2021-35939 : Exploit Details and Defense Strategies

A local unprivileged user could potentially exploit a vulnerability in RPM to gain root privileges, impacting data confidentiality, integrity, and system availability.

Understanding CVE-2021-35939

This CVE highlights an incomplete fix in RPM, which could lead to a privilege escalation attack by a local user.

What is CVE-2021-35939?

The incomplete fix for CVE-2017-7500 and CVE-2017-7501 in RPM allows a local user to gain root privileges by manipulating ancestor directories.

The Impact of CVE-2021-35939

The primary risk of this vulnerability is to data confidentiality, integrity, and system availability.

Technical Details of CVE-2021-35939

The vulnerability in RPM stems from improper directory checks, enabling a user to escalate privileges.

Vulnerability Description

The flawed fix in RPM allows a local unprivileged user to exploit ancestor directories and potentially gain root access.

Affected Systems and Versions

RPM version 4.18 is affected by this vulnerability, although it has been fixed in RPM-v4.18.

Exploitation Mechanism

By manipulating ancestor directories, a local user who owns directories can exploit this vulnerability to escalate privileges.

Mitigation and Prevention

Addressing CVE-2021-35939 requires immediate action to prevent unauthorized privilege escalation.

Immediate Steps to Take

Update RPM to version RPM-v4.18 to apply the fix for this vulnerability.
Monitor system logs for any suspicious activity that could indicate exploitation.

Long-Term Security Practices

Implement the principle of least privilege to limit user access.
Conduct regular security audits to identify and address vulnerabilities.

Patching and Updates

Regularly apply security patches and updates to all software components to mitigate the risk of similar vulnerabilities.