T1166 · threatengine.sh

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ATT&CK Technique

Setuid and Setgid

T1166 · privilege-escalation, persistence

▤ Generate a SIEM detection for T1166 ◈ Deployable detections for T1166 ⚠ CVEs mapped to T1166 ♛ Hunt package for T1166

When the setuid or setgid bits are set on Linux or macOS for an application, this means that the application will run with the privileges of the owning user or group respectively. Normally an application is run in the current user’s context, regardless of which user or group owns the application. There are instances where programs need to be executed in an elevated context to function properly, but the user running them doesn’t need the elevated privileges.

Instead of creating an entry in the sudoers file, which must be done by root, any user can specify the setuid or setgid flag to be set for their own applications. These bits are indicated with an "s" instead of an "x" when viewing a file's attributes via ls -l. The chmod program can set these bits with via bitmasking, chmod 4777 [file] or via shorthand naming, chmod u+s [file].

An adversary can take advantage of this to either do a shell escape or exploit a vulnerability in an application with the setsuid or setgid bits to get code running in a different user’s context. Additionally, adversaries can use this mechanism on their own malware to make sure they're able to execute in elevated contexts in the future.

LinuxmacOS

▸ How to use this page - the detection-engineering loop

Attackers have goals (tactics - “get credentials”, “move laterally”) and techniques are the concrete methods they use to reach them. This page is one method - T1166 - broken into everything you need to catch it.

The loop this page is built for (this is the job):

Understand the behaviour - read the description and the Atomic Tests to see exactly what the attacker does on a host or network.
Find the telemetry - what data source would reveal it (process creation, registry, network flow, auth logs). Detection Coverage shows which surfaces already have a rule and which are blind.
Get or write the detection - adapt ready logic (CAR Analytics, SIEM Detections, Falco, or Sigma via Generate a SIEM detection), or author your own.
Test it - run an Atomic Test in a lab and confirm your rule actually fires. A detection you have not tested is a hope, not coverage.
Deploy and tune - push it, then watch for false positives and adjust.

What each panel is for:

Atomic Testssafely reproduce the technique in a lab to validate that a detection fires. Detection Coveragewhich detection surfaces have a rule for this technique; none is a blind spot to close, or simply not applicable (YARA matches files, not network behaviour). CAR / SIEM / Falcoready-made detection logic (Splunk SPL, Elastic EQL, Sentinel KQL, Falco) you adapt to your own SIEM. Mitigationsreduce exposure so the technique is harder to use at all - prevent, not just detect. Actors / Attributionwho actually uses this, so you prioritise by your own threat model. Attack Path / LOTLwhat attackers do before and after this step, and the legitimate tools they abuse to do it.

Where this fits: you usually arrive here from a CVE (“which techniques does it enable”) and leave with a tested detection deployed. The buttons above jump straight to building one, the deployable rules, the CVEs that use T1166, and a hunt package.

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Detection Coverage

0/9 layers

Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).

Behavioral / log (Sigma) none

Analytics (MITRE CAR) none

Runtime / container (Falco) none

File / malware (YARA) none

Network (Suricata/Snort) none

Vuln scan (Nuclei) none

SIEM (Splunk ESCU) none

SIEM (Elastic) none

SIEM (Azure Sentinel) none

External lookups - second-class, for what we don’t hold ourselves

MITRE ATT&CK Atomic Red Team car (MITRE)