Startup/Logon Script Added to Group Policy Object

Status: test
Severity: medium
Log source: product windows, service security
Author: Elastic, Josh Nickels, Marius Rothenbücher
Source: github.com/SigmaHQ/sigma

Detects the modification of Group Policy Objects (GPO) to add a startup/logon script to users or computer objects.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1547` Boot or Logon Autostart Execution
Privilege Escalation	`T1484.001` Domain or Tenant Policy Modification: Group Policy Modification, `T1547` Boot or Logon Autostart Execution
Defense Impairment	`T1484.001` Domain or Tenant Policy Modification: Group Policy Modification

Event coverage

Provider	Event	Title
Security-Auditing	Event ID 5136	A directory service object was modified.
Security-Auditing	Event ID 5145	A network share object was checked to see whether client can be granted desired access.

Rule body yaml

title: Startup/Logon Script Added to Group Policy Object
id: 123e4e6d-b123-48f8-b261-7214938acaf0
status: test
description: |
    Detects the modification of Group Policy Objects (GPO) to add a startup/logon script to users or computer objects.
references:
    - https://www.elastic.co/guide/en/security/current/startup-logon-script-added-to-group-policy-object.html
author: Elastic, Josh Nickels, Marius Rothenbücher
date: 2024-09-06
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.defense-impairment
    - attack.t1484.001
    - attack.t1547
logsource:
    product: windows
    service: security
    definition: 'The advanced audit policy setting "Object Access > Audit Detailed File Share" must be configured for Success/Failure'
detection:
    selection_eventid:
        EventID:
            - 5136
            - 5145
    selection_attributes_main:
        AttributeLDAPDisplayName:
            - 'gPCMachineExtensionNames'
            - 'gPCUserExtensionNames'
        AttributeValue|contains: '42B5FAAE-6536-11D2-AE5A-0000F87571E3'
    selection_attributes_optional:
        AttributeValue|contains:
            - '40B6664F-4972-11D1-A7CA-0000F87571E3'
            - '40B66650-4972-11D1-A7CA-0000F87571E3'
    selection_share:
        ShareName|endswith: '\SYSVOL'
        RelativeTargetName|endswith:
            - '\scripts.ini'
            - '\psscripts.ini'
        AccessList|contains: '%%4417'
    condition: selection_eventid and (all of selection_attributes_* or selection_share)
falsepositives:
    - Legitimate execution by system administrators.
level: medium

Stages and Predicates

Stage 0: `condition`

selection_eventid and (all of selection_attributes_* or selection_share)

Stage 1: `selection_eventid`

selection_eventid:
    EventID:
        - 5136
        - 5145

Stage 2: `selection_attributes_main`

selection_attributes_main:
    AttributeLDAPDisplayName:
        - 'gPCMachineExtensionNames'
        - 'gPCUserExtensionNames'
    AttributeValue|contains: '42B5FAAE-6536-11D2-AE5A-0000F87571E3'

Stage 3: `selection_attributes_optional`

selection_attributes_optional:
    AttributeValue|contains:
        - '40B6664F-4972-11D1-A7CA-0000F87571E3'
        - '40B66650-4972-11D1-A7CA-0000F87571E3'

Stage 4: `selection_share`

selection_share:
    ShareName|endswith: '\SYSVOL'
    RelativeTargetName|endswith:
        - '\scripts.ini'
        - '\psscripts.ini'
    AccessList|contains: '%%4417'

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
`AccessList`	match	`%%4417` corpus 11 (sigma 8, elastic 2, splunk 1)
`AttributeLDAPDisplayName`	eq	`gPCMachineExtensionNames` corpus 7 (sigma 3, elastic 3, splunk 1) `gPCUserExtensionNames` corpus 4 (sigma 2, elastic 2)
`AttributeValue`	match	`40B6664F-4972-11D1-A7CA-0000F87571E3` corpus 2 (sigma 1, elastic 1) `40B66650-4972-11D1-A7CA-0000F87571E3` corpus 2 (sigma 1, elastic 1) `42B5FAAE-6536-11D2-AE5A-0000F87571E3` corpus 2 (sigma 1, elastic 1)
`RelativeTargetName`	ends_with	`\psscripts.ini` corpus 2 (sigma 1, elastic 1) `\scripts.ini` corpus 2 (sigma 1, elastic 1)
`ShareName`	ends_with	`\SYSVOL` corpus 2 (sigma 2)

`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)

Startup/Logon Script Added to Group Policy Object

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_eventid`

Stage 2: `selection_attributes_main`

Stage 3: `selection_attributes_optional`

Stage 4: `selection_share`

Indicators

Keyboard shortcuts

Search operators

Startup/Logon Script Added to Group Policy Object

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_eventid

Stage 2: selection_attributes_main

Stage 3: selection_attributes_optional

Stage 4: selection_share

Indicators

Stage 0: `condition`

Stage 1: `selection_eventid`

Stage 2: `selection_attributes_main`

Stage 3: `selection_attributes_optional`

Stage 4: `selection_share`