Detection rules › Splunk
Suspicious Certificate Modification (Windows Event Log)
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
Event coverage
Rule body yaml
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
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 |
|---|---|---|
EventCode | eq |
|
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 | TERM |
| 1 | "<EventID>4891<" |
| 1 | TERM |
| 1 | "<EventID>4892<" |
| 1 | TERM |
| 1 | "<EventID>4890<" |
| 1 | TERM |
| 1 | "<EventID>4882<" |