Detection rules › Splunk
Modify Windows Defender (EDR)
Adversaries may modify security tools to avoid possible detection of their tools and activities. This use case looks for abnormalities commonly associated with a large number of modifications to windows defender in a short period of time
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1562.001 Impair Defenses: Disable or Modify Tools |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '5996.12246'
title: Modify Windows Defender
description: 'Adversaries may modify security tools to avoid possible detection of
their tools and activities. This use case looks for abnormalities commonly associated
with a large number of modifications to windows defender in a short period of time.
-- Threat Actor Association: BlackByte, Lazarus, Magic Hound (aka APT35, Charming
Kitten, Phosphorus, and Mint Sandstorm), Memento Team, Muddled Libra, REvil, Vice
Society - Software Association: Akira, BianLian, Black Basta, Lockbit, Snake, Vice
Society, XingLocker, Zloader'
logic_format: Splunk
logic: ' `get_endpoint_data` `get_endpoint_data_edr` ((event_type IN ("childproc","netconn","proc"))
OR (TERM(ProcessRollup2) OR Type=Process) OR TERM(DeviceProcessEvents)) (TERM(Set-MpPreference)
OR TERM(Add-MpPreference)) | table _time, host, user process, process_*, singature_id,
parent_* | bin span=60s | stats values(*) as * by _time, host | eventstats dc(process)
as dc_process by host, _time | where dc_process >= 1 | fields - dc_* `hec_collect`'
techniques:
- defense-evasion:impair defenses:disable or modify tools
technique_id:
- T1562.001
data_category:
- EDR Logs
- Process command-line parameters
references:
- https://unit42.paloaltonetworks.com/unit42-gorgon-group-slithering-nation-state-cybercrime/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_edr` ((event_type IN ("childproc","netconn","proc")) OR (TERM(ProcessRollup2) OR Type=Process) OR TERM(DeviceProcessEvents)) (TERM(Set-MpPreference) OR TERM(Add-MpPreference))
Stage 2: table
| table _time, host, user process, process_*, singature_id, parent_*
Stage 3: bucket
| bin span=60s
Stage 4: stats
| stats values(*) as * by _time, host
Stage 5: eventstats
| eventstats dc(process) as dc_process by host, _time
Stage 6: where
| where dc_process >= 1
Stage 7: fields
| fields - dc_* `hec_collect`
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 |
|---|---|---|
dc_process | ge |
|
event_type | in |
|
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 | ProcessRollup2 |
| 1 | TERM |
| 1 | DeviceProcessEvents |
| 1 | "Set-MpPreference" |
| 1 | "Add-MpPreference" |