Suspicious Process Access to LSASS with Dbgcore/Dbghelp DLLs — Sigma Rule

Rule metadata and linked tags

Author: Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: high. Source dates: 2025-11-27 / not supplied.

{
  "category": "process_access",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: dacc54eb8b938b8c1badfcf2dd299d18a6f31d1e46dacaf7a60e65a9862cc512

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Suspicious Process Access to LSASS with Dbgcore/Dbghelp DLLs
id: 9f5c1d59-33be-4e60-bcab-85d2f566effd
related:
    - id: 416bc4a2-7217-4519-8dc7-c3271817f1d5
      type: similar
status: experimental
description: |
    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.
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
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-11-27
tags:
    - attack.credential-access
    - attack.defense-impairment
    - attack.t1003.001
    - attack.t1685
logsource:
    category: process_access
    product: windows
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_*
falsepositives:
    - Possibly during software installation or update processes
level: high
regression_tests_path: regression_data/rules/windows/process_access/proc_access_win_susp_dbgcore_dbghelp_load/info.yml

Original YAML and metadata in JSON

False positives

• Possibly during software installation or update processes

Source 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