Detect LSASS Memory in Splunk
Adversaries access credential material stored in the LSASS process memory. After logon, Windows stores credentials (NTLM hashes, Kerberos tickets, plaintext passwords via WDigest) in LSASS. Tools used include Mimikatz, ProcDump, comsvcs.dll MiniDump (rundll32.exe C:\Windows\System32\comsvcs.dll MiniDump), WerFault silent process exit, and Cobalt Strike's sekurlsa module. Used extensively by APT1, APT33, OilRig, HAFNIUM, Volt Typhoon, NotPetya, Cobalt Strike operators, and many others. Highest-frequency credential dumping technique observed in the wild.
MITRE ATT&CK
- Tactic
- Credential Access
- Technique
- T1003 OS Credential Dumping
- Sub-technique
- T1003.001 LSASS Memory
- Canonical reference
- https://attack.mitre.org/techniques/T1003/001/
SPL Detection Query
index=wineventlog sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=10
TargetImage="*\\lsass.exe"
NOT (SourceImage="*\\MsMpEng.exe" OR SourceImage="*\\csrss.exe" OR SourceImage="*\\services.exe"
OR SourceImage="*\\lsm.exe" OR SourceImage="*\\svchost.exe" OR SourceImage="*\\winlogon.exe"
OR SourceImage="*\\wininit.exe" OR SourceImage="*\\SecurityHealthService.exe")
| eval HighAccess=if(match(GrantedAccess, "^0x(1[fF][3f][fF]{3}|1[fF][fF]{4}|143[aA]|1[04][01][0a0])"), 1, 0)
| where HighAccess=1
| table _time, host, SourceImage, SourceCommandLine, GrantedAccess, SourceUser
| sort - _time
| append
[search index=wineventlog sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=1
((Image="*\\rundll32.exe" CommandLine="*comsvcs*" CommandLine="*MiniDump*")
OR (Image="*\\procdump*.exe" CommandLine="*lsass*"))
| eval DetectionType=case(
match(CommandLine, "comsvcs"), "ComsvcsMinidump",
match(Image, "procdump"), "ProcDumpLsass",
1==1, "Other"
)
| table _time, host, Image, CommandLine, User, DetectionType]Detects LSASS credential dumping via Sysmon Event ID 10 (Process Access) with high-privilege access masks, combined with Sysmon Event ID 1 for comsvcs.dll MiniDump command pattern and ProcDump targeting lsass. The union catches Mimikatz-style injection (EventCode=10) and LOLBin-based dumping (EventCode=1).
Data Sources
Required Sourcetypes
False Positives & Tuning
- EDR agent processes performing LSASS memory inspection
- Antivirus software accessing LSASS for behavioral monitoring
- Windows Defender accessing LSASS during AMSI scanning
- Legitimate administrator ProcDump usage with authorized change ticket
Other platforms for T1003.001
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 1LSASS Dump via comsvcs.dll MiniDump (LOLBin)
Expected signal: Sysmon Event ID 1: Process Create for rundll32.exe with CommandLine containing comsvcs.dll MiniDump. Sysmon Event ID 10: ProcessAccess for lsass.exe from rundll32.exe with GrantedAccess=0x1fffff. Sysmon Event ID 11: FileCreate for the .dmp file in C:\Windows\Temp\.
- Test 2LSASS Access via PowerShell Reflection (Mimikatz-Style)
Expected signal: Sysmon Event ID 10: ProcessAccess with TargetImage=lsass.exe, SourceImage=powershell.exe. The GrantedAccess value depends on the access requested by Get-Process. Security Event ID 4656/4663 if process object auditing is enabled.
- Test 3LSASS Dump via ProcDump
Expected signal: Sysmon Event ID 10: ProcessAccess with TargetImage=lsass.exe, SourceImage=procdump.exe, GrantedAccess=0x1fffff. Sysmon Event ID 11: FileCreate for lsass_pd_test.dmp. Sysmon Event ID 1: Process Create for procdump.exe with lsass.exe in CommandLine.
References (7)
- https://attack.mitre.org/techniques/T1003/001/
- https://medium.com/threatpunter/detecting-attempts-to-steal-passwords-from-memory-558f16dce4ea
- https://www.volexity.com/blog/2021/03/02/active-exploitation-of-microsoft-exchange-zero-day-vulnerabilities/
- https://www.deepinstinct.com/blog/lsass-memory-dumps-are-stealthier-than-ever-before-part-2
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1003.001/T1003.001.md
- https://docs.microsoft.com/en-us/windows/security/identity-protection/credential-guard/credential-guard
- https://learn.microsoft.com/en-us/windows-server/security/credentials-protection-and-management/configuring-additional-lsa-protection
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