Detect CVE-2026-48769 — Incus Arbitrary File Write via Trusted Image Hash in Elastic Security
Detects exploitation of CVE-2026-48769, a critical arbitrary file write vulnerability in Incus (github.com/lxc/incus/v7/cmd/incusd) versions prior to 7.2.0. The flaw arises from improper validation (CWE-20) of image hashes during image pull operations, allowing a malicious or compromised image source to write arbitrary files on the Incus client host system. With a CVSS score of 9.9 and public PoC available, this vulnerability is actively exploitable and may lead to full host compromise, container escape, or persistence via overwritten system binaries or configuration files.
MITRE ATT&CK
Elastic Detection Query
sequence by host.id with maxspan=5m
[process where event.type == "start"
and process.name in ("incus", "incusd")
and process.args : ("image copy", "image pull", "image import", "launch")]
[file where event.type in ("creation", "change")
and process.name in ("incus", "incusd")
and (
file.path like "/etc/*" or
file.path like "/usr/bin/*" or
file.path like "/usr/sbin/*" or
file.path like "/bin/*" or
file.path like "/sbin/*" or
file.path like "/lib/*" or
file.path like "/root/*" or
file.path like "/home/*"
)
]EQL sequence rule correlating an Incus image pull/launch process start event with a subsequent file write to sensitive host paths within 5 minutes, both attributed to incusd.
Data Sources
Required Tables
False Positives & Tuning
- Incus storage driver operations writing to configured pool directories that overlap with monitored paths
- Post-install hooks from container images that are expected to modify host networking configuration
- Security scanning tools that launch Incus containers and monitor resulting file activity
Other platforms for CVE-2026-48769
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 1Simulate CVE-2026-48769 — Malicious Image Serving Arbitrary File Write
Expected signal: Process event: incus or incusd spawning with 'image copy' in command line; File creation event: /tmp/pwned created by incusd process; Network connection: incusd connecting to 127.0.0.1:18443
- Test 2Incus Version Detection and Vulnerable Host Discovery
Expected signal: Process events showing incus/incusd invoked with --version or version subcommand; curl process accessing /var/lib/incus/unix.socket
- Test 3Post-Exploitation — Persistence via Written Cron Job
Expected signal: Process event: process named incusd writing to /etc/cron.d/; File creation event: /etc/cron.d/incus-update created; auditd AVC or WRITE record for /etc/cron.d/
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