Read-Only Attribute Removed - Windows (PowerShell)

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

This use case detects commands removing read-only attributes from files on Windows systems. This technique is used by threat actors to modify or delete critical system files

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1222.001` File and Directory Permissions Modification: Windows Permissions

References

https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1222.001/T1222.001.md#atomic-test-3---attrib---remove-read-only-attribute

Telemetry coverage

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

Rule body

id: '17778.29995'
title: Read-Only Attribute Removed - Windows
description: 'This use case detects commands removing read-only attributes from files
  on Windows systems. This technique is used by threat actors to modify or delete
  critical system files. Atomics T1222.001 Test #3'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4103) OR
  "<EventID>4103<" OR TERM(EventCode=4104) OR "<EventID>4104<") (TERM(attrib) OR TERM(attrib.exe))
  "-r" | regex process="(?i)\s+-r\s+" | table _time, host, user parent_*, process,
  process_* | bin span=1s | stats values(*) as * by _time, host '
techniques:
- defense-evasion:file and directory permissions modification:windows file and directory
  permissions modification
technique_id:
- T1222.001
data_category:
- PowerShell logs
references:
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1222.001/T1222.001.md#atomic-test-3---attrib---remove-read-only-attribute

Stages and Predicates

Stage 1: `search`

`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4103) OR "<EventID>4103<" OR TERM(EventCode=4104) OR "<EventID>4104<") (TERM(attrib) OR TERM(attrib.exe)) "-r"

Stage 2: `regex`

| regex process="(?i)\s+-r\s+"

Stage 3: `table`

| table _time, host, user parent_*, process, process_*

Stage 4: `bucket`

| bin span=1s

Stage 5: `stats`

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

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventCode`	eq	`4103` corpus 105 (splunk 105) `4104` corpus 269 (splunk 269)	`field:"EventID" kind:eq`
`process`	regex_match	`"(?i)\s+-r\s+"` corpus 3 (splunk 3)	`field:"CommandLine" kind:regex_match`

Search terms

These SPL tokens match against raw event text.

Stage	Term
1	`"<EventID>4103<"`
1	`"<EventID>4104<"`
1	`attrib`
1	`attrib.exe`
1	`"-r"`