LSASS Driver
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).
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 descData Sources
Required Tables
False Positives
- 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
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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