CVE-2019-20044 : Exploit Details and Defense Strategies

Zsh before version 5.8 allows attackers executing commands to regain dropped privileges by exploiting the --no-PRIVILEGED option. This vulnerability enables the restoration of original privileges by executing specific commands with a module that includes the setuid() function.

Understanding CVE-2019-20044

Zsh vulnerability pre-version 5.8

What is CVE-2019-20044?

In Zsh before version 5.8, attackers executing commands can regain privileges dropped by the --no-PRIVILEGED option. Zsh fails to overwrite the saved uid, allowing the restoration of original privileges.

The Impact of CVE-2019-20044

Attackers can regain dropped privileges by exploiting the vulnerability
Restoration of original privileges through specific commands

Technical Details of CVE-2019-20044

Zsh vulnerability details

Vulnerability Description

Prior to Zsh version 5.8, individuals with the ability to execute commands can regain dropped privileges by exploiting the --no-PRIVILEGED option. Zsh is unable to properly overwrite the saved uid, thus enabling the restoration of original privileges by executing specific commands.

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions affected: Not applicable

Exploitation Mechanism

Attackers execute commands to regain dropped privileges
Exploiting the --no-PRIVILEGED option
Restoration of original privileges by executing specific commands

Mitigation and Prevention

Protecting against CVE-2019-20044

Immediate Steps to Take

Update Zsh to version 5.8 or newer
Monitor for any unauthorized privilege changes
Implement least privilege access

Long-Term Security Practices

Regularly update and patch software
Conduct security training to educate users on safe practices

Patching and Updates

Apply security updates promptly
Follow vendor advisories for patch releases