CVE-2017-5226
📋 TL;DR
CVE-2017-5226 is a critical sandbox escape vulnerability in bubblewrap that allows unprivileged processes to inject terminal commands into the parent session using the TIOCSTI ioctl. This affects any system using bubblewrap for sandboxing applications, particularly container runtimes and Linux desktop applications. Attackers can break out of the sandbox and execute arbitrary commands with the privileges of the parent process.
💻 Affected Systems
- bubblewrap
- Flatpak
- podman
- containers using bubblewrap for sandboxing
📦 What is this software?
Bubblewrap by Projectatomic
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via privilege escalation from unprivileged user to root, allowing installation of persistent malware, data exfiltration, and lateral movement.
Likely Case
Sandbox escape leading to execution of arbitrary commands with the privileges of the parent bubblewrap process, potentially gaining elevated privileges on the host system.
If Mitigated
Limited impact if bubblewrap is used with minimal privileges and proper isolation controls, though sandbox integrity would still be compromised.
🎯 Exploit Status
Exploitation requires access to execute code within the bubblewrap sandbox. The TIOCSTI technique is well-documented and easy to implement.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: bubblewrap with commit d7fc532c42f0e9bf427923bab85433282b3e5117 or later
Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1411811
Restart Required: No
Instructions:
1. Update bubblewrap package using your distribution's package manager. 2. For Flatpak: Update to version 0.8.7 or later. 3. For podman/containers: Ensure underlying bubblewrap is updated. 4. Rebuild any containers using vulnerable bubblewrap versions.
🔧 Temporary Workarounds
Disable TIOCSTI ioctl
linuxBlock the TIOCSTI ioctl at the kernel level using seccomp filters or disable terminal session sharing in bubblewrap.
bwrap --unshare-all --seccomp 10 /path/to/program
echo 0 > /proc/sys/kernel/tiocsti
Run without terminal session
linuxAvoid sharing terminal sessions between bubblewrap and parent process.
bwrap --unshare-ipc --unshare-net --unshare-pid --unshare-uts --unshare-cgroup --unshare-user /path/to/program
🧯 If You Can't Patch
- Isolate bubblewrap processes using namespaces and cgroups to limit blast radius
- Implement strict seccomp profiles to block TIOCSTI and other dangerous syscalls
🔍 How to Verify
Check if Vulnerable:
Check bubblewrap version: bwrap --version | grep -q 'd7fc532c42f0e9bf427923bab85433282b3e5117' && echo 'Patched' || echo 'Vulnerable'Check Version:
bwrap --versionVerify Fix Applied:
Test with a proof-of-concept that attempts TIOCSTI injection; successful patch will prevent command injection.📡 Detection & Monitoring
Log Indicators:
- Unusual terminal input sequences from bubblewrap processes
- Failed TIOCSTI ioctl attempts in audit logs
Network Indicators:
- Sudden outbound connections from bubblewrap processes
SIEM Query:
process.name='bwrap' AND syscall.name='ioctl' AND syscall.args.cmd='TIOCSTI'🔗 References
- http://www.openwall.com/lists/oss-security/2020/07/10/1
- http://www.openwall.com/lists/oss-security/2023/03/17/1
- http://www.securityfocus.com/bid/97260
- https://bugzilla.redhat.com/show_bug.cgi?id=1411811
- https://github.com/projectatomic/bubblewrap/commit/d7fc532c42f0e9bf427923bab85433282b3e5117
- https://github.com/projectatomic/bubblewrap/issues/142
- https://www.openwall.com/lists/oss-security/2023/03/14/2
- http://www.openwall.com/lists/oss-security/2020/07/10/1
- http://www.openwall.com/lists/oss-security/2023/03/17/1
- http://www.securityfocus.com/bid/97260
- https://bugzilla.redhat.com/show_bug.cgi?id=1411811
- https://github.com/projectatomic/bubblewrap/commit/d7fc532c42f0e9bf427923bab85433282b3e5117
- https://github.com/projectatomic/bubblewrap/issues/142
- https://www.openwall.com/lists/oss-security/2023/03/14/2
