Sigma rule: Potentially Suspicious GrantedAccess Flags On LSASS

Rule

Title

Potentially Suspicious GrantedAccess Flags On LSASS

Status

test

Level

medium

Author

Florian Roth, Roberto Rodriguez, Dimitrios Slamaris, Mark Russinovich, Thomas Patzke, Teymur Kheirkhabarov, Sherif Eldeeb, James Dickenson, Aleksey Potapov, oscd.community

Date

2021-11-22

Modified

2026-10-20

File

rules/windows/process_access/proc_access_win_lsass_susp_access_flag.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects process access requests to LSASS process with potentially suspicious access flags

Log source

product

windows

category

process_access

Detection

selection_target:
    TargetImage|endswith: '\lsass.exe'
selection_access:
    - GrantedAccess|endswith:
          # - '10'  # covered in rule 678dfc63-fefb-47a5-a04c-26bcf8cc9f65
          - '30'
          - '50'
          - '70'
          - '90'
          - 'B0'
          - 'D0'
          - 'F0'
          - '18'
          - '38'
          - '58'
          - '78'
          - '98'
          - 'B8'
          - 'D8'
          - 'F8'
          - '1A'
          - '3A'
          - '5A'
          - '7A'
          - '9A'
          - 'BA'
          - 'DA'
          - 'FA'
          - '0x14C2'  # https://github.com/b4rtik/ATPMiniDump/blob/76304f93b390af3bb66e4f451ca16562a479bdc9/ATPMiniDump/ATPMiniDump.c
    - GrantedAccess|startswith:
          # - '0x100000'  # SYNCHRONIZE - cannot be used for credential dumping; high FP rate from AV/EDR agents synchronizing on LSASS
          - '0x1418'    # car.2019-04-004
          - '0x1438'    # car.2019-04-004
          - '0x143a'    # car.2019-04-004
          - '0x1f0fff'
          - '0x1f1fff'
          - '0x1f2fff'
          - '0x1f3fff'
          - '0x40'
          # - '0x1000'  # minimum access requirements to query basic info from service
          # - '0x1010'    # car.2019-04-004
          # - '0x1400'
          # - '0x1410'    # car.2019-04-004 # Covered by 678dfc63-fefb-47a5-a04c-26bcf8cc9f65
filter_main_generic:
    # When using this rule. Remove this filter and replace it by the path of the specific AV you use
    SourceImage|contains:
        - ':\Program Files (x86)\'
        - ':\Program Files\'
        - ':\Windows\System32\'
        - ':\Windows\SysWOW64\'
filter_optional_malwarebytes:
    SourceImage|endswith: ':\ProgramData\MALWAREBYTES\MBAMSERVICE\ctlrupdate\mbupdatr.exe'
filter_optional_vscode:
    SourceImage|endswith: '\AppData\Local\Programs\Microsoft VS Code\Code.exe'
filter_main_windefend_1:
    SourceImage|contains: ':\ProgramData\Microsoft\Windows Defender\'
    SourceImage|endswith: '\MsMpEng.exe'
filter_main_windefend_2:
    CallTrace|contains|all:
        - '|?:\ProgramData\Microsoft\Windows Defender\Definition Updates\{'
        - '}\mpengine.dll+'
    GrantedAccess: '0x1418'
filter_main_windefend_3:
    CallTrace|contains:
        - '|c:\program files\windows defender\mprtp.dll'
        - '|c:\program files\windows defender\MpClient.dll'
filter_optional_vmwaretools:
    SourceImage|contains: ':\ProgramData\VMware\VMware Tools\'
    SourceImage|endswith: '\vmtoolsd.exe'
filter_optional_sysinternals_process_explorer:
    SourceImage|endswith:
        - '\PROCEXP64.EXE'
        - '\PROCEXP.EXE'
    GrantedAccess: '0x40'
filter_optional_mbami:
    SourceImage|endswith: '\MBAMInstallerService.exe'
    GrantedAccess: '0x40'
filter_optional_nextron:
    SourceImage|endswith:
        - '\aurora-agent-64.exe'
        - '\aurora-agent.exe'
        - '\thor.exe'
        - '\thor64.exe'
    GrantedAccess: '0x40'
filter_main_explorer:
    SourceImage|endswith: '\explorer.exe'
    GrantedAccess: '0x401'
filter_optional_sysinternals_handle:
    SourceImage|endswith:
        - '\handle.exe'
        - '\handle64.exe'
        - '\handle64a.exe'
    GrantedAccess: '0x40'
filter_optional_webex:
    SourceImage|endswith: '\AppData\Local\WebEx\WebexHost.exe'
    GrantedAccess: '0x401'
filter_optional_steam_apps:
    SourceImage|contains: '\SteamLibrary\steamapps\'
condition: all of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*

False positives (as the rule lists them)

• Legitimate software such as AV and EDR

Tags

• attack.credential-access
• attack.t1003.001
• attack.s0002

MITRE ATT&CK ids this rule names

• S0002
• T1003.001

Related rules

• 32d0d3e2-e58d-4d41-926b-18b520b2b32d (similar)

References

• https://learn.microsoft.com/en-us/windows/win32/procthread/process-security-and-access-rights
• https://onedrive.live.com/view.aspx?resid=D026B4699190F1E6!2843&ithint=file%2cpptx&app=PowerPoint&authkey=!AMvCRTKB_V1J5ow
• https://web.archive.org/web/20230208123920/https://cyberwardog.blogspot.com/2017/03/chronicles-of-threat-hunter-hunting-for_22.html
• https://www.slideshare.net/heirhabarov/hunting-for-credentials-dumping-in-windows-environment
• https://web.archive.org/web/20230420013146/http://security-research.dyndns.org/pub/slides/FIRST2017/FIRST-2017_Tom-Ueltschi_Sysmon_FINAL_notes.pdf

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_lsass_susp_access_flag.yml