CVE-2018-6954 : Exploit Details and Defense Strategies
Learn about CVE-2018-6954, a vulnerability in systemd-tmpfiles allowing local users to gain ownership of files by manipulating symlinks. Find out the impact, affected systems, exploitation mechanism, and mitigation steps.
A vulnerability has been discovered in systemd-tmpfiles in systemd version 237 and earlier, allowing local users to gain ownership of different files by manipulating symlinks present in non-terminal path components.
Understanding CVE-2018-6954
This CVE involves a vulnerability in systemd-tmpfiles that can be exploited by local users to manipulate symlinks and gain ownership of files.
What is CVE-2018-6954?
systemd-tmpfiles in systemd through version 237 mishandles symlinks in non-terminal path components, enabling local users to obtain ownership of arbitrary files by creating a directory, a file within that directory, and replacing the directory with a symlink, even if fs.protected_symlinks sysctl is enabled.
The Impact of CVE-2018-6954
The vulnerability allows unauthorized local users to take ownership of files on the system, potentially leading to unauthorized access and manipulation of sensitive data.
Technical Details of CVE-2018-6954
This section provides technical details about the vulnerability.
Vulnerability Description
The vulnerability in systemd-tmpfiles allows local users to manipulate symlinks in non-terminal path components, leading to unauthorized ownership of files on the system.
Affected Systems and Versions
- Affected version: systemd version 237 and earlier
- Affected systems: Systems running systemd versions 237 and prior
Exploitation Mechanism
The attack involves the following steps:
- Creating a directory
- Creating a file within the directory
- Replacing the directory with a symlink
Mitigation and Prevention
Protect your system from CVE-2018-6954 with the following steps:
Immediate Steps to Take
- Update systemd to a non-vulnerable version
- Implement least privilege access controls
- Monitor system logs for suspicious activities
Long-Term Security Practices
- Regularly update and patch system software
- Conduct security training for users on symlink manipulation risks
- Implement file system integrity checks
Patching and Updates
- Apply patches provided by the vendor to fix the vulnerability
- Stay informed about security advisories and updates from relevant sources