Detect LSASS Driver in Microsoft Sentinel
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/
KQL Detection Query
let KnownLsaDlls = dynamic(["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"]);
DeviceImageLoadEvents
| where Timestamp > ago(24h)
| where InitiatingProcessFileName =~ "lsass.exe"
| where not(FileName in~ (KnownLsaDlls))
| where not(FolderPath startswith "C:\\Windows\\System32\\" or FolderPath startswith "C:\\Windows\\SysWOW64\\")
| project Timestamp, DeviceName, FileName, FolderPath, SHA256, InitiatingProcessFileName
| sort by Timestamp descDetects DLL loads into lsass.exe from non-standard file locations. Legitimate LSASS DLLs are loaded from System32. Any DLL loaded from another path, or an unknown DLL loaded from System32, indicates potential LSASS driver abuse for persistence and credential access.
Data Sources
Required Tables
False Positives & Tuning
- Third-party security products (EDR, DLP) that inject DLLs into lsass.exe for monitoring
- Smart card middleware and biometric authentication providers loading credential provider DLLs
- Windows Updates or patches loading new or updated LSA DLLs
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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