Uncommon Service Installation Image Path

Status: test
Severity: medium
Log source: product windows, service system
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects uncommon service installation commands by looking at suspicious or uncommon image path values containing references to encoded powershell commands, temporary paths, etc.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1543.003` Create or Modify System Process: Windows Service
Privilege Escalation	`T1543.003` Create or Modify System Process: Windows Service

Event coverage

Provider	Event
Service-Control-Manager	Event ID 7045

Rule body yaml

title: Uncommon Service Installation Image Path
id: 26481afe-db26-4228-b264-25a29fe6efc7
related:
    - id: ca83e9f3-657a-45d0-88d6-c1ac280caf53
      type: obsolete
    - id: 1d61f71d-59d2-479e-9562-4ff5f4ead16b
      type: derived
status: test
description: |
    Detects uncommon service installation commands by looking at suspicious or uncommon image path values containing references to encoded powershell commands, temporary paths, etc.
references:
    - Internal Research
author: Florian Roth (Nextron Systems)
date: 2022-03-18
modified: 2024-02-09
tags:
    - attack.persistence
    - attack.privilege-escalation
    - car.2013-09-005
    - attack.t1543.003
logsource:
    product: windows
    service: system
detection:
    selection:
        Provider_Name: 'Service Control Manager'
        EventID: 7045
    suspicious_paths:
        ImagePath|contains:
            - '\\\\.\\pipe'
            - '\Users\Public\'
            - '\Windows\Temp\'
    suspicious_encoded_flag:
        ImagePath|contains: ' -e'
    suspicious_encoded_keywords:
        ImagePath|contains:
            - ' aQBlAHgA' # PowerShell encoded commands
            - ' aWV4I' # PowerShell encoded commands
            - ' IAB' # PowerShell encoded commands
            - ' JAB' # PowerShell encoded commands
            - ' PAA' # PowerShell encoded commands
            - ' SQBFAFgA' # PowerShell encoded commands
            - ' SUVYI' # PowerShell encoded commands
    filter_optional_thor_remote:
        ImagePath|startswith: 'C:\WINDOWS\TEMP\thor10-remote\thor64.exe'
    filter_main_defender_def_updates:
        ImagePath|startswith: 'C:\ProgramData\Microsoft\Windows Defender\Definition Updates\'
    condition: selection and ( suspicious_paths or all of suspicious_encoded_* ) and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

selection and ( suspicious_paths or all of suspicious_encoded_* ) and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: `selection`

selection:
    Provider_Name: 'Service Control Manager'
    EventID: 7045

Stage 2: `suspicious_paths`

suspicious_paths:
    ImagePath|contains:
        - '\\\\.\\pipe'
        - '\Users\Public\'
        - '\Windows\Temp\'

Stage 3: `suspicious_encoded_flag`

suspicious_encoded_flag:
    ImagePath|contains: ' -e'

Stage 4: `suspicious_encoded_keywords`

suspicious_encoded_keywords:
    ImagePath|contains:
        - ' aQBlAHgA'
        - ' aWV4I'
        - ' IAB'
        - ' JAB'
        - ' PAA'
        - ' SQBFAFgA'
        - ' SUVYI'

Stage 5: `not filter_main_defender_def_updates`

filter_main_defender_def_updates:
    ImagePath|startswith: 'C:\ProgramData\Microsoft\Windows Defender\Definition Updates\'

Stage 6: `not filter_optional_thor_remote`

filter_optional_thor_remote:
    ImagePath|startswith: 'C:\WINDOWS\TEMP\thor10-remote\thor64.exe'

Exclusions

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

Field	Kind	Excluded values
`ImagePath`	starts_with	`C:\ProgramData\Microsoft\Windows Defender\Definition Updates\`
`ImagePath`	starts_with	`C:\WINDOWS\TEMP\thor10-remote\thor64.exe`

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
`ImagePath`	match	`-e` `IAB` `JAB` `PAA` `SQBFAFgA` `SUVYI` `aQBlAHgA` `aWV4I` `\Users\Public\` `\Windows\Temp\` `\\\\.\\pipe`
`Provider_Name`	eq	`Service Control Manager` corpus 50 (sigma 50)

`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)

Uncommon Service Installation Image Path

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `suspicious_paths`

Stage 3: `suspicious_encoded_flag`

Stage 4: `suspicious_encoded_keywords`

Stage 5: `not filter_main_defender_def_updates`

Stage 6: `not filter_optional_thor_remote`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Uncommon Service Installation Image Path

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: suspicious_paths

Stage 3: suspicious_encoded_flag

Stage 4: suspicious_encoded_keywords

Stage 5: not filter_main_defender_def_updates

Stage 6: not filter_optional_thor_remote

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `suspicious_paths`

Stage 3: `suspicious_encoded_flag`

Stage 4: `suspicious_encoded_keywords`

Stage 5: `not filter_main_defender_def_updates`

Stage 6: `not filter_optional_thor_remote`