macOS Setuid/Setgid Privilege Escalation

Status: experimental
Severity: high
Log source: product macos, service endpointsecurity
Author: Eric Brown - Nebulock, Inc.
Source: github.com/Nebulock-Inc/macos-coresigma

Detects setuid or setgid operations that transition to root (UID 0) from non-root users, which may indicate privilege escalation attempts. These syscalls allow processes to change their effective user ID or group ID, often used by attackers to gain elevated privileges. High-fidelity detection focuses on transitions to root from non-privileged users.

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1068` Exploitation for Privilege Escalation, `T1548.001` Abuse Elevation Control Mechanism: Setuid and Setgid

Rule body yaml

title: macOS Setuid/Setgid Privilege Escalation
id: 0f3109b3-d7e5-4c8a-a082-d8f0fa7be7a1
status: experimental
description: 'Detects setuid or setgid operations that transition to root (UID 0) from
  non-root users, which may indicate privilege escalation attempts.

  These syscalls allow processes to change their effective user ID or group ID, often

  used by attackers to gain elevated privileges. High-fidelity detection focuses on

  transitions to root from non-privileged users.

  '
author: Eric Brown - Nebulock, Inc.
date: 2025/10/31
modified: 2025/10/31
references:
- https://attack.mitre.org/techniques/T1548/001/
- https://attack.mitre.org/techniques/T1068/
logsource:
  product: macos
  service: endpointsecurity
detection:
  selection_setuid:
    esf.event_type: 24
    event.action: setuid
  selection_setgid:
    esf.event_type: 25
    event.action: setgid
  selection_to_root:
    TargetUserId: 0
  selection_root_source:
    UserId: 0
  condition: (selection_setuid or selection_setgid) and selection_to_root and not selection_root_source
falsepositives:
- Legitimate system utilities and services
- Software installation and updates
- Authorized administrative tools
fields:
- event_type
- event_name
- ProcessId
- User
- UserId
- TargetUser
- TargetUserId
tags:
- attack.privilege_escalation
- attack.t1548.001
- attack.t1068
level: high

Stages and Predicates

Stage 0: `condition`

(selection_setuid or selection_setgid) and selection_to_root and not selection_root_source

Stage 1: `selection_setuid`

selection_setuid:
  esf.event_type: 24
  event.action: setuid

Stage 2: `selection_setgid`

selection_setgid:
  esf.event_type: 25
  event.action: setgid

Stage 3: `selection_to_root`

selection_to_root:
  TargetUserId: 0

Stage 4: `not selection_root_source`

selection_root_source:
  UserId: 0

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`UserId`	eq	`0`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`TargetUserId`	eq	`0`
`esf.event_type`	eq	`24` `25`
`event.action`	eq	`setgid` `setuid`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

macOS Setuid/Setgid Privilege Escalation

MITRE ATT&CK coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_setuid`

Stage 2: `selection_setgid`

Stage 3: `selection_to_root`

Stage 4: `not selection_root_source`

Exclusions

Indicators

Keyboard shortcuts

Search operators

macOS Setuid/Setgid Privilege Escalation

MITRE ATT&CK coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_setuid

Stage 2: selection_setgid

Stage 3: selection_to_root

Stage 4: not selection_root_source

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_setuid`

Stage 2: `selection_setgid`

Stage 3: `selection_to_root`

Stage 4: `not selection_root_source`