Sigma rule: Suspicious Process Access to LSASS with Dbgcore/Dbghelp DLLs

Rule

Title

Suspicious Process Access to LSASS with Dbgcore/Dbghelp DLLs

Status

experimental

Level

high

Author

Swachchhanda Shrawan Poudel (Nextron Systems)

Date

2025-11-27

File

rules/windows/process_access/proc_access_win_susp_dbgcore_dbghelp_load.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious process access to LSASS.exe from processes located in uncommon locations with dbgcore.dll or dbghelp.dll in the call trace.
These DLLs contain functions like MiniDumpWriteDump that can be abused for credential dumping purposes. While modern tools like Mimikatz have moved to using ntdll.dll,
dbgcore.dll and dbghelp.dll are still used by basic credential dumping utilities and legacy tools for LSASS memory access and process suspension techniques.

Log source

product

windows

category

process_access

Detection

selection_lsass_calltrace:
    TargetImage|endswith: '\lsass.exe'
    CallTrace|contains:
        - 'dbgcore.dll'
        - 'dbghelp.dll'
# The following selection is commented out and not enabled by default because any access to LSASS with dbgcore.dll or dbghelp.dll in the call trace from uncommon locations is assumed to be suspicious,
# but it may reduce false positives if the rule is too noisy. These GrantedAccess bits are commonly used for dumping LSASS memory.
# Uncomment if you observe false positives with the default rule.
# selection_granted_access:
#     GrantedAccess|contains:
#         - '0x1fffff'
#         - '0x10'
#         - '0x1010'
#         - '0x1410'
#         - '0x1438'
selection_susp_location:
    SourceImage|contains:
        - ':\Perflogs\'
        - ':\Temp\'
        - ':\Users\Public\'
        - '\$Recycle.Bin\'
        - '\AppData\Roaming\'
        - '\Contacts\'
        - '\Desktop\'
        - '\Documents\'
        - '\Downloads\'
        - '\Favorites\'
        - '\Favourites\'
        - '\inetpub\wwwroot\'
        - '\Music\'
        - '\Pictures\'
        - '\Start Menu\Programs\Startup\'
        - '\Users\Default\'
        - '\Videos\'
        - '\Windows\Temp\'
condition: all of selection_*

False positives (as the rule lists them)

• Possibly during software installation or update processes

Tags

• attack.credential-access
• attack.defense-impairment
• attack.t1003.001
• attack.t1685

MITRE ATT&CK ids this rule names

• T1003.001
• T1685

Related rules

• 416bc4a2-7217-4519-8dc7-c3271817f1d5 (similar)

References

• https://www.splunk.com/en_us/blog/security/you-bet-your-lsass-hunting-lsass-access.html
• https://docs.microsoft.com/en-us/windows/win32/api/minidumpapiset/nf-minidumpwritedump

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_access/proc_access_win_susp_dbgcore_dbghelp_load.yml