ATBroker.exe Execution (PowerShell)

Group by: _time, host
Source: github.com/anvilogic-forge/armory

Helper binary for Assistive Technology (AT), Executes code defined in registry for a new AT. Modifications must be made to the system registry to either register or modify an existing Assistive Technology (AT) service entry

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218` System Binary Proxy Execution

References

Event coverage

Provider	Event	Title
PowerShell	Event ID 4103	Payload Context: ContextInfo User Data: UserData.
PowerShell	Event ID 4104	Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body yaml

id: '6076.18329'
title: ATBroker.exe Execution
description: Helper binary for Assistive Technology (AT), Executes code defined in
  registry for a new AT. Modifications must be made to the system registry to either
  register or modify an existing Assistive Technology (AT) service entry. Living Off
  the Land Binary and Scripts (LOLBAS) (LOLBIN)
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` ("EventCode=4104" OR "<EventID>4104<"
  OR "EventCode=4103" OR "<EventID>4103<") "ATBroker.exe" TERM(/start) | table _time,
  host, user, signature_id, process, process_*, parent_process_* | bin span=1s | stats
  values(*) as * by _time, host '
techniques:
- defense-evasion:system binary proxy execution
technique_id: 
- T1218
data_category:
- PowerShell logs
references:
- http://www.hexacorn.com/blog/2016/07/22/beyond-good-ol-run-key-part-42/
- https://oddvar.moe/2018/07/23/another-way-to-get-to-a-system-shell/

Stages and Predicates

Stage 1: `search`

`get_endpoint_data` `get_endpoint_data_powershell` ("EventCode=4104" OR "<EventID>4104<" OR "EventCode=4103" OR "<EventID>4103<") "ATBroker.exe" TERM(/start)

Stage 2: `table`

| table _time, host, user, signature_id, process, process_*, parent_process_*

Stage 3: `bucket`

| bin span=1s

Stage 4: `stats`

| stats values(*) as * by _time, host

Search terms

Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.

Stage	Term
1	`"EventCode=4104"`
1	`"<EventID>4104<"`
1	`"EventCode=4103"`
1	`"<EventID>4103<"`
1	`"ATBroker.exe"`
1	`"/start"`

`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)

ATBroker.exe Execution (PowerShell)

MITRE ATT&CK coverage

References

Event coverage

Rule body yaml

Stages and Predicates

Stage 1: `search`

Stage 2: `table`

Stage 3: `bucket`

Stage 4: `stats`

Search terms

Keyboard shortcuts

Search operators

ATBroker.exe Execution (PowerShell)

MITRE ATT&CK coverage

References

Event coverage

Rule body yaml

Stages and Predicates

Stage 1: search

Stage 2: table

Stage 3: bucket

Stage 4: stats

Search terms

Stage 1: `search`

Stage 2: `table`

Stage 3: `bucket`

Stage 4: `stats`