Meterpreter or Cobalt Strike Getsystem Service Installation - Security

Status: test
Severity: high
Log source: product windows, service security
Author: Teymur Kheirkhabarov, Ecco, Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the use of getsystem Meterpreter/Cobalt Strike command by detecting a specific service installation

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1134.001` Access Token Manipulation: Token Impersonation/Theft, `T1134.002` Access Token Manipulation: Create Process with Token
Stealth	`T1134.001` Access Token Manipulation: Token Impersonation/Theft, `T1134.002` Access Token Manipulation: Create Process with Token

Event coverage

Provider	Event	Title
Security-Auditing	Event ID 4697	A service was installed in the system.

Rule body yaml

title: Meterpreter or Cobalt Strike Getsystem Service Installation - Security
id: ecbc5e16-58e0-4521-9c60-eb9a7ea4ad34
related:
    - id: 843544a7-56e0-4dcc-a44f-5cc266dd97d6
      type: derived
status: test
description: Detects the use of getsystem Meterpreter/Cobalt Strike command by detecting a specific service installation
references:
    - https://speakerdeck.com/heirhabarov/hunting-for-privilege-escalation-in-windows-environment
    - https://blog.cobaltstrike.com/2014/04/02/what-happens-when-i-type-getsystem/
author: Teymur Kheirkhabarov, Ecco, Florian Roth (Nextron Systems)
date: 2019-10-26
modified: 2023-11-15
tags:
    - attack.privilege-escalation
    - attack.stealth
    - attack.t1134.001
    - attack.t1134.002
logsource:
    product: windows
    service: security
    definition: The 'System Security Extension' audit subcategory need to be enabled to log the EID 4697
detection:
    selection_eid:
        EventID: 4697
    selection_cli_cmd:
        # meterpreter getsystem technique 1: cmd.exe /c echo 559891bb017 > \\.\pipe\5e120a
        # cobaltstrike getsystem technique 1: %COMSPEC% /c echo 559891bb017 > \\.\pipe\5e120a
        # cobaltstrike getsystem technique 1b (expanded %COMSPEC%): %COMSPEC% /c echo 559891bb017 > \\.\pipe\5e120a
        ServiceFileName|contains|all:
            - '/c'
            - 'echo'
            - '\pipe\'
        ServiceFileName|contains:
            - 'cmd'
            - '%COMSPEC%'
    selection_cli_rundll:
        # meterpreter getsystem technique 2: rundll32.exe C:\Users\test\AppData\Local\Temp\tmexsn.dll,a /p:tmexsn
        ServiceFileName|contains|all:
            - 'rundll32'
            - '.dll,a'
            - '/p:'
    selection_cli_share:
        ServiceFileName|startswith: '\\\\127.0.0.1\\ADMIN$\'  # https://twitter.com/svch0st/status/1413688851877416960?lang=en
    condition: selection_eid and 1 of selection_cli_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

selection_eid and 1 of selection_cli_*

Stage 1: `selection_eid`

selection_eid:
    EventID: 4697

Stage 2: `selection_cli_cmd`

selection_cli_cmd:
    ServiceFileName|contains|all:
        - '/c'
        - 'echo'
        - '\pipe\'
    ServiceFileName|contains:
        - 'cmd'
        - '%COMSPEC%'

Stage 3: `selection_cli_rundll`

selection_cli_rundll:
    ServiceFileName|contains|all:
        - 'rundll32'
        - '.dll,a'
        - '/p:'

Stage 4: `selection_cli_share`

selection_cli_share:
    ServiceFileName|startswith: '\\\\127.0.0.1\\ADMIN$\'

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
`ServiceFileName`	match	`%COMSPEC%` corpus 2 (sigma 2) `.dll,a` `/c` corpus 3 (sigma 3) `/p:` `\pipe\` `cmd` corpus 5 (sigma 5) `echo` `rundll32` corpus 2 (sigma 2)
`ServiceFileName`	starts_with	`\\\\127.0.0.1\\ADMIN$\`

`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)

Meterpreter or Cobalt Strike Getsystem Service Installation - Security

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_eid`

Stage 2: `selection_cli_cmd`

Stage 3: `selection_cli_rundll`

Stage 4: `selection_cli_share`

Indicators

Keyboard shortcuts

Search operators

Meterpreter or Cobalt Strike Getsystem Service Installation - Security

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_eid

Stage 2: selection_cli_cmd

Stage 3: selection_cli_rundll

Stage 4: selection_cli_share

Indicators

Stage 0: `condition`

Stage 1: `selection_eid`

Stage 2: `selection_cli_cmd`

Stage 3: `selection_cli_rundll`

Stage 4: `selection_cli_share`