CVE-2019-7639 : Exploit Details and Defense Strategies
Discover the impact of CVE-2019-7639, allowing unauthorized access to systems by enabling users to log in with a valid username and incorrect password. Learn how to mitigate this vulnerability.
A problem was found in Fedora 29's gsi-openssh-server version 7.9p1 where users can log in with a correct username and an incorrect password when PermitPAMUserChange is enabled.
Understanding CVE-2019-7639
What is CVE-2019-7639?
An issue in gsi-openssh-server 7.9p1 on Fedora 29 allows users to log in with a valid username and an incorrect password, despite recording a failed login attempt.
The Impact of CVE-2019-7639
This vulnerability enables unauthorized access to systems by allowing users to bypass password authentication.
Technical Details of CVE-2019-7639
Vulnerability Description
- Vulnerability in gsi-openssh-server 7.9p1 on Fedora 29
- PermitPAMUserChange setting allows login with correct username and incorrect password
Affected Systems and Versions
- Affected system: Fedora 29
- Affected version: gsi-openssh-server 7.9p1
Exploitation Mechanism
- Users exploit the PermitPAMUserChange setting to log in with incorrect passwords
Mitigation and Prevention
Immediate Steps to Take
- Disable PermitPAMUserChange setting in /etc/gsissh/sshd_config
- Monitor logs for unusual login activities
Long-Term Security Practices
- Implement multi-factor authentication
- Regularly review and update security configurations
Patching and Updates
- Apply patches and updates provided by the vendor to fix the vulnerability