Suspicious Certificate Modification (Windows Event Log)

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

Adversaries may modify an AD CA’s root certificate, and in order to gain ans use a certificate for any active user or computer

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1556` Modify Authentication Process
Defense Impairment	`T1556` Modify Authentication Process
Credential Access	`T1556` Modify Authentication Process

References

Telemetry coverage

Provider	Record / event type
Security-Auditing	Event ID 4882: The security permissions for Certificate Services changed.
Security-Auditing	Event ID 4890: The certificate manager settings for Certificate Services changed.
Security-Auditing	Event ID 4891: A configuration entry changed in Certificate Services.
Security-Auditing	Event ID 4892: A property of Certificate Services changed.

Rule body

id: '8661.11208'
title: Suspicious Certificate Modification
description: 'Adversaries may modify an AD CA’s root certificate, and in order to
  gain ans use a certificate for any active user or computer. - Threat Actor Association:
  APT29'
logic_format: Splunk
logic: ' `get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4891) OR
  "<EventID>4891<" OR TERM(EventCode=4892) OR "<EventID>4892<" OR TERM(EventCode=4890)
  OR "<EventID>4890<" OR TERM(EventCode=4882) OR "<EventID>4882<") | table _time,
  host, user process, process_*, parent_process, parent_process_*, src_*, dest_*,
  subject | bin span=1s | stats values(*) as * by _time, host '
techniques:
- persistence:modify authentication process
technique_id: 
- T1556
data_category:
- Windows event logs
references:
- https://www.specterops.io/assets/resources/Certified_Pre-Owned.pdf
- https://github.com/GhostPack/Certify#using-requested-certificates

Stages and Predicates

Stage 1: `search`

`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4891) OR "<EventID>4891<" OR TERM(EventCode=4892) OR "<EventID>4892<" OR TERM(EventCode=4890) OR "<EventID>4890<" OR TERM(EventCode=4882) OR "<EventID>4882<")

Stage 2: `table`

| table _time, host, user process, process_*, parent_process, parent_process_*, src_*, dest_*, subject

Stage 3: `bucket`

| bin span=1s

Stage 4: `stats`

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

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventCode`	eq	`4882` `4890` `4891` `4892`	`field:"EventID" kind:eq`

Search terms

These SPL tokens match against raw event text.

Stage	Term
1	`"<EventID>4891<"`
1	`"<EventID>4892<"`
1	`"<EventID>4890<"`
1	`"<EventID>4882<"`