Detection rules › Splunk
Potential LSA password filter (Windows Event Log)
Adversaries may register malicious password filter dynamic link libraries (DLLs) into the authentication process to acquire user credentials as they are validated. Windows password filters are password policy enforcement mechanisms for both domain and local accounts. This use case looks for values added to LSA registry with reg.exe
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | T1547.002 Boot or Logon Autostart Execution: Authentication Package, T1556.002 Modify Authentication Process: Password Filter DLL |
| Privilege Escalation | T1547.002 Boot or Logon Autostart Execution: Authentication Package |
| Defense Impairment | T1556.002 Modify Authentication Process: Password Filter DLL |
| Credential Access | T1556.002 Modify Authentication Process: Password Filter DLL |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '8154.10006'
title: Potential LSA password filter
description: 'Adversaries may register malicious password filter dynamic link libraries
(DLLs) into the authentication process to acquire user credentials as they are validated.
Windows password filters are password policy enforcement mechanisms for both domain
and local accounts. This use case looks for values added to LSA registry with reg.exe
- Software Association: Cactus, Vice Society - Atomics T1556.002 Test #1'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process) TERM(add) "control" "lsa" | table _time, host,
user process, process_*, signature_id, parent_* | bin span=1s | stats values(*)
as * by _time, host '
techniques:
- defense-evasion:modify authentication process:password filter dll
- privilege-escalation:boot or logon autostart execution:authentication package
- persistence:boot or logon autostart execution:authentication package
- persistence:modify authentication process:password filter dll
- credential-access:modify authentication process:password filter dll
technique_id:
- T1556.002
- T1547.002
data_category:
- Windows event logs
- Process command-line parameters
references:
- https://media.kasperskycontenthub.com/wp-content/uploads/sites/43/2018/03/07190154/The-ProjectSauron-APT_research_KL.pdf
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) TERM(add) "control" "lsa"
Stage 2: table
| table _time, host, user process, process_*, signature_id, parent_*
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>4688<" |
| 1 | TERM |
| 1 | add |
| 1 | "control" |
| 1 | "lsa" |