Detection rules › Splunk
WFP Filter and Provider Changed (Windows Event Log)
Threat actors may abuse Windows Filtering Platform filters to prevent EDR agents from reporting security events, as observed with tools like EDRSilencer or EDRNoisemaker. This use case detects when a host has events for both WFP provider and filter changes within a short time period (default 30s).
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1562 Impair Defenses |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 5447 | A Windows Filtering Platform filter has been changed. |
| Security-Auditing | Event ID 5448 | A Windows Filtering Platform provider has been changed. |
Rule body yaml
id: '38988.70115'
title: WFP Filter and Provider Changed
description: Threat actors may abuse Windows Filtering Platform filters to prevent
EDR agents from reporting security events, as observed with tools like EDRSilencer
or EDRNoisemaker. This use case detects when a host has events for both WFP provider
and filter changes within a short time period (default 30s).
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=5447) OR
"<EventID>5447<" OR TERM(EventCode=5448) OR "<EventID>5448<") | regex user!="NT\sAUTHORITY|\$$"
| table _time, host, user, process, process_*, parent_process_name, user, signature_id
| bin span=30s | stats values(*) as * by _time, host | where match(signature_id,
"5447") and match(signature_id, "5448") '
techniques:
- defense-evasion:impair defenses
technique_id:
- T1562
data_category:
- Windows event logs
references:
- https://github.com/netero1010/EDRSilencer
- https://github.com/amjcyber/EDRNoiseMaker
- https://ghoulsec.medium.com/misc-series-4-forensics-on-edrsilencer-events-428b20b3f983
- https://www.huntress.com/blog/silencing-the-edr-silencers
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=5447) OR "<EventID>5447<" OR TERM(EventCode=5448) OR "<EventID>5448<")
Stage 2: regex
| regex user!="NT\sAUTHORITY|\$$"
Stage 3: table
| table _time, host, user, process, process_*, parent_process_name, user, signature_id
Stage 4: bucket
| bin span=30s
Stage 5: stats
| stats values(*) as * by _time, host
Stage 6: where
| where match(signature_id, "5447") and match(signature_id, "5448")
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
user | regex_match | "NT\sAUTHORITY, $$" |
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 |
|
signature_id | match |
|
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>5447<" |
| 1 | TERM |
| 1 | "<EventID>5448<" |