Detect Linux Kernel cgroup v1 release_agent Privilege Escalation (CVE-2022-0492) in Elastic Security
CVE-2022-0492 is a Linux kernel vulnerability (CWE-287/CWE-862) in the cgroup v1 release_agent mechanism. A local unprivileged user can exploit improper capability checks to write to /sys/fs/cgroup/*/release_agent and execute arbitrary commands as root, enabling container escape and full host compromise. This vulnerability is listed on CISA KEV, indicating active exploitation in the wild.
MITRE ATT&CK
Elastic Detection Query
sequence by host.id with maxspan=2m
[
process where event.type == "start" and
(
process.name in ("unshare", "nsenter") or
process.args : ("/sys/fs/cgroup*", "*release_agent*", "*notify_on_release*")
)
] by process.pid
[
file where event.action in ("creation", "overwrite") and
file.path : "/sys/fs/cgroup/*/release_agent"
] by process.pid
[
process where event.type == "start" and
process.parent.name in ("runc", "containerd-shim", "sh", "bash")
and process.user.id == "0"
] by process.parent.pidEQL sequence detecting the three-stage pattern of CVE-2022-0492 exploitation: namespace manipulation → release_agent file write → privileged process execution, correlated by process ID within a 2-minute window.
Data Sources
Required Tables
False Positives & Tuning
- Automated container management platforms triggering cgroup cleanup handlers
- Security scanning tools exercising cgroup filesystem paths
- Legitimate privilege transitions during container startup orchestrated by trusted runtimes
- Kernel module testing in development environments
Other platforms for CVE-2022-0492
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Write payload to cgroup release_agent (non-privileged namespace simulation)
Expected signal: Process event for unshare with -UrmC flags; file write event to path matching /sys/fs/cgroup/*/release_agent or the tmp mount path; child bash process inheriting modified cgroup namespace
- Test 2Enumerate cgroup v1 hierarchy for exploitable release_agent
Expected signal: Process event for sh/bash with find commands targeting /sys/fs/cgroup paths; multiple file read events against notify_on_release and release_agent pseudo-files
- Test 3Container escape simulation via cgroup release_agent (lab environment)
Expected signal: Docker daemon log showing privileged container creation; host-level process events for cgroup mount, release_agent write; if successful: unexpected process spawned outside container namespace with UID 0; file creation event for escape_proof.txt on host
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