Detect Incus exec-output Symlink Arbitrary File Write on Host (CVE-2026-48750) in CrowdStrike LogScale
CVE-2026-48750 is a critical arbitrary file write vulnerability (CVSS 9.9) in Incus container/VM manager (github.com/lxc/incus/v7/cmd/incusd) versions prior to 7.2.0. A crafted container image can place a symlink at the exec-output path, causing incusd to write attacker-controlled content to arbitrary locations on the host filesystem. This enables container escape leading to full host compromise. A public PoC is available.
MITRE ATT&CK
LogScale Detection Query
event_simpleName IN (ProcessRollup2, SyntheticProcessRollup2, FileOpenInfo, FileWrittenInfo)
| eval is_incus_parent = if(match(ParentBaseFileName, "incusd|incus"), 1, 0)
| eval sensitive_path = if(match(TargetFileName, "^/(etc|root|var/spool/cron|usr/local/bin|lib/systemd|home/[^/]+/\.ssh)/"), 1, 0)
| eval exec_output_ref = if(match(CommandLine, "exec.output|exec_output"), 1, 0)
| where is_incus_parent=1 AND (sensitive_path=1 OR exec_output_ref=1)
| eval threat = "CVE-2026-48750 Incus exec-output symlink host file write"
| table timestamp, ComputerName, UserName, ParentBaseFileName, FileName, CommandLine, TargetFileName, threat
| sort - timestampCrowdStrike Falcon Query Language detection for incusd-parented processes writing to sensitive host paths or referencing exec-output, covering both process and file write telemetry.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate incus daemon file operations during authorized container provisioning
- Security research environments where incus exec-output is intentionally exercised
- Automated deployment pipelines using incus that write artifacts to system directories in controlled settings
Other platforms for CVE-2026-48750
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 1Create malicious symlink in exec-output path within container image
Expected signal: Auditd symlink syscall from process tree rooted at incusd; file write event to /etc/passwd path originating from incusd child process
- Test 2Detect symlink traversal via exec-output to /root/.ssh/authorized_keys
Expected signal: File write syscall to /root/.ssh/authorized_keys with incusd ancestor in process tree; auditd type=PATH record for authorized_keys
- Test 3Simulate exec-output symlink to systemd service unit for persistence
Expected signal: File creation event under /lib/systemd/system/ with incusd ancestor; subsequent systemd daemon-reload or service enable events
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