Detect LSASS Driver in Google Chronicle
Adversaries may modify or add LSASS drivers to obtain persistence on compromised systems. The Windows security subsystem is a set of components that manage and enforce the security policy for a computer or domain. The Local Security Authority (LSA) is the main component responsible for local security policy and user authentication. The LSA includes multiple DLLs associated with various security functions, all running in the context of the LSASS process (lsass.exe). Adversaries may target LSASS drivers to obtain persistence. By either replacing or adding illegitimate drivers, an adversary can use LSA operations to continuously execute malicious payloads. Known examples include Wingbird (which drops sspisrv.dll alongside lsass.exe) and Pasam (which infects the SAM DLL).
MITRE ATT&CK
- Tactic
- Persistence Privilege Escalation
- Technique
- T1547 Boot or Logon Autostart Execution
- Sub-technique
- T1547.008 LSASS Driver
- Canonical reference
- https://attack.mitre.org/techniques/T1547/008/
YARA-L Detection Query
rule lsass_driver_implant_t1547_008 {
meta:
author = "Argus Detection Engineering"
description = "Detects non-standard DLL loads by lsass.exe from outside trusted Windows system directories, indicating a potential LSA driver implant for persistence (T1547.008)"
mitre_attack_tactic = "Persistence"
mitre_attack_technique = "T1547.008"
severity = "CRITICAL"
confidence = "HIGH"
created = "2026-04-20"
events:
$e.metadata.event_type = "PROCESS_MODULE_LOAD"
$e.principal.process.file.full_path = /(?i)\\lsass\.exe$/
not $e.target.file.full_path = /(?i)^[Cc]:\\Windows\\System32\\/
not $e.target.file.full_path = /(?i)^[Cc]:\\Windows\\SysWOW64\\/
not $e.target.file.full_path = /(?i)^[Cc]:\\Windows\\WinSxS\\/
not $e.target.file.full_path = /(?i)\\(msv1_0\.dll|kerberos\.dll|wdigest\.dll|tspkg\.dll|schannel\.dll|pku2u\.dll|cloudAP\.dll|negoexts\.dll|msprivs\.dll|lsasrv\.dll|samsrv\.dll|ntdsai\.dll)$/
condition:
$e
}Chronicle YARA-L 2.0 rule detecting unauthorized DLL image loads by lsass.exe from non-system directories. Uses UDM PROCESS_MODULE_LOAD events to identify potential LSASS driver implants consistent with Wingbird or Pasam-style persistence techniques targeting the Local Security Authority.
Data Sources
Required Tables
False Positives & Tuning
- Enterprise password filter DLLs registered in HKLM\SYSTEM\CurrentControlSet\Control\Lsa\Notification Packages loaded from custom application install paths rather than System32
- Third-party smart card middleware that registers as an LSA authentication package and loads from a vendor-specific directory during user logon operations
- Security products performing in-process LSASS instrumentation for privileged access protection, such as Microsoft Defender Credential Guard supplemental modules or CyberArk AIM agents
Other platforms for T1547.008
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Drop DLL Alongside LSASS Copy (Wingbird Pattern)
Expected signal: Sysmon Event ID 11: FileCreate for both lsass.exe and sspisrv.dll in C:\Windows\Temp\. The co-location of these files in a non-standard path is the indicator.
- Test 2Enumerate LSASS Loaded Modules
Expected signal: Sysmon Event ID 1: Process creation for tasklist with /m /fi flags targeting lsass.exe.
- Test 3Check LSA Protection Status
Expected signal: Sysmon Event ID 1: Process creation for reg.exe querying the LSA key.
References (5)
- https://attack.mitre.org/techniques/T1547/008/
- https://technet.microsoft.com/library/dn408187.aspx
- https://technet.microsoft.com/library/cc961760.aspx
- https://msdn.microsoft.com/library/windows/desktop/ff919712.aspx
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1547.008/T1547.008.md
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