CVE-2022-27239
📋 TL;DR
A stack-based buffer overflow vulnerability in cifs-utils versions through 6.14 allows local attackers to escalate privileges to root when parsing the ip= argument in mount.cifs command. This affects Linux systems using cifs-utils for mounting SMB/CIFS shares.
💻 Affected Systems
- cifs-utils
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
Linux Enterprise High Performance Computing by Suse
View all CVEs affecting Linux Enterprise High Performance Computing →
Linux Enterprise High Performance Computing by Suse
View all CVEs affecting Linux Enterprise High Performance Computing →
Linux Enterprise High Performance Computing by Suse
View all CVEs affecting Linux Enterprise High Performance Computing →
Linux Enterprise High Performance Computing by Suse
View all CVEs affecting Linux Enterprise High Performance Computing →
Linux Enterprise High Performance Computing by Suse
View all CVEs affecting Linux Enterprise High Performance Computing →
Linux Enterprise High Performance Computing by Suse
View all CVEs affecting Linux Enterprise High Performance Computing →
Linux Enterprise High Performance Computing by Suse
View all CVEs affecting Linux Enterprise High Performance Computing →
Linux Enterprise High Performance Computing by Suse
View all CVEs affecting Linux Enterprise High Performance Computing →
⚠️ Risk & Real-World Impact
Worst Case
Local unprivileged user gains full root privileges on the system, enabling complete system compromise.
Likely Case
Local attacker with shell access escalates to root and installs persistence mechanisms or accesses sensitive data.
If Mitigated
With proper privilege separation and SELinux/apparmor, impact limited to filesystem access within the mount context.
🎯 Exploit Status
Exploit requires local shell access. Proof of concept available in bug reports.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: cifs-utils 6.15 and later
Vendor Advisory: https://bugzilla.samba.org/show_bug.cgi?id=15025
Restart Required: No
Instructions:
1. Update cifs-utils package using your distribution's package manager. 2. For Debian/Ubuntu: sudo apt update && sudo apt install cifs-utils. 3. For RHEL/CentOS: sudo yum update cifs-utils. 4. For SUSE: sudo zypper update cifs-utils.
🔧 Temporary Workarounds
Remove SUID bit from mount.cifs
linuxRemove setuid permission from mount.cifs binary to prevent privilege escalation.
sudo chmod u-s /sbin/mount.cifs
Restrict mount.cifs execution
linuxUse sudoers to restrict who can execute mount.cifs with elevated privileges.
Add to /etc/sudoers: username ALL=(ALL) NOPASSWD: /sbin/mount.cifs
🧯 If You Can't Patch
- Remove SUID bit from mount.cifs binary to prevent privilege escalation
- Implement strict sudoers policies to limit mount.cifs execution to trusted users only
🔍 How to Verify
Check if Vulnerable:
Check cifs-utils version: dpkg -l cifs-utils | grep ^ii or rpm -q cifs-utils. If version is 6.14 or earlier, system is vulnerable.Check Version:
dpkg -l cifs-utils 2>/dev/null || rpm -q cifs-utils 2>/dev/null || pacman -Qi cifs-utils 2>/dev/nullVerify Fix Applied:
Verify version is 6.15 or later: cifs-utils --version 2>/dev/null | head -1📡 Detection & Monitoring
Log Indicators:
- Failed mount attempts with unusually long ip= parameters
- Sudden privilege escalation events from mount.cifs
Network Indicators:
- Unusual SMB mount attempts from local users
SIEM Query:
process.name="mount.cifs" AND command_line CONTAINS "ip=" AND command_line LENGTH > 100🔗 References
- http://wiki.robotz.com/index.php/Linux_CIFS_Utils_and_Samba
- https://bugzilla.samba.org/show_bug.cgi?id=15025
- https://bugzilla.suse.com/show_bug.cgi?id=1197216
- https://github.com/piastry/cifs-utils/pull/7
- https://github.com/piastry/cifs-utils/pull/7/commits/955fb147e97a6a74e1aaa65766de91e2c1479765
- https://lists.debian.org/debian-lts-announce/2022/05/msg00020.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5WBOLMANBYJILXQKRRK7OCR774PXJAYY/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HXKZLJYJJEC3TIBFLXUORRMZUKG5W676/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QIYZ4L6SLSYJQ446VJAO2VGAESURQNSP/
- https://security.gentoo.org/glsa/202311-05
- https://www.debian.org/security/2022/dsa-5157
- http://wiki.robotz.com/index.php/Linux_CIFS_Utils_and_Samba
- https://bugzilla.samba.org/show_bug.cgi?id=15025
- https://bugzilla.suse.com/show_bug.cgi?id=1197216
- https://github.com/piastry/cifs-utils/pull/7
- https://github.com/piastry/cifs-utils/pull/7/commits/955fb147e97a6a74e1aaa65766de91e2c1479765
- https://lists.debian.org/debian-lts-announce/2022/05/msg00020.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5WBOLMANBYJILXQKRRK7OCR774PXJAYY/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HXKZLJYJJEC3TIBFLXUORRMZUKG5W676/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QIYZ4L6SLSYJQ446VJAO2VGAESURQNSP/
- https://security.gentoo.org/glsa/202311-05
- https://www.debian.org/security/2022/dsa-5157
