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Detection rules › Sigma

Potentially Suspicious Volume Shadow Copy Vsstrace.dll Load

Status
test
Severity
medium
Log source
category image_load, product windows
Author
frack113
Source
github.com/SigmaHQ/sigma

Detects the image load of VSS DLL by uncommon executables

MITRE ATT&CK coverage

TacticTechniques
Impact

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 7: Image loaded

Rule body

title: Potentially Suspicious Volume Shadow Copy Vsstrace.dll Load
id: 48bfd177-7cf2-412b-ad77-baf923489e82
related:
    - id: 333cdbe8-27bb-4246-bf82-b41a0dca4b70 # vss_ps.dll
      type: similar
    - id: 37774c23-25a1-4adb-bb6d-8bb9fd59c0f8 # vssapi.dll
      type: similar
status: test
description: Detects the image load of VSS DLL by uncommon executables
references:
    - https://github.com/ORCx41/DeleteShadowCopies
author: frack113
date: 2023-02-17
modified: 2025-12-03
tags:
    - attack.impact
    - attack.t1490
logsource:
    category: image_load
    product: windows
detection:
    selection:
        ImageLoaded|endswith: '\vsstrace.dll'
    filter_main_windows:
        - Image:
              - 'C:\Windows\explorer.exe'
              - 'C:\Windows\ImmersiveControlPanel\SystemSettings.exe'
        - Image|startswith:
              - 'C:\Windows\System32\'
              - 'C:\Windows\SysWOW64\'
              - 'C:\Windows\Temp\{' # Installers
              - 'C:\Windows\WinSxS\'
              - 'C:\ProgramData\Package Cache\{'  # Microsoft Visual Redistributable installer  VC_redist/vcredist EXE
    filter_main_program_files:
        # When using this rule in your environment replace the "Program Files" folder by the exact applications you know use this. Examples would be software such as backup solutions
        Image|startswith:
            - 'C:\Program Files\'
            - 'C:\Program Files (x86)\'
    filter_optional_recovery:
        Image|startswith: 'C:\$WinREAgent\Scratch\'
    filter_main_null_image:
        Image: null # Observed through Aurora
    filter_optional_avira:
        Image|contains|all:
            - '\temp\is-'
            - '\avira_system_speedup.tmp'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: selection

selection:
    ImageLoaded|endswith: '\vsstrace.dll'

Stage 2: not filter_main_*

filter_main_windows:
    - Image:
          - 'C:\Windows\explorer.exe'
          - 'C:\Windows\ImmersiveControlPanel\SystemSettings.exe'
    - Image|startswith:
          - 'C:\Windows\System32\'
          - 'C:\Windows\SysWOW64\'
          - 'C:\Windows\Temp\{'
          - 'C:\Windows\WinSxS\'
          - 'C:\ProgramData\Package Cache\{'
filter_main_program_files:
    Image|startswith:
        - 'C:\Program Files\'
        - 'C:\Program Files (x86)\'
filter_main_null_image:
    Image: null

Stage 3: not filter_optional_*

filter_optional_recovery:
    Image|startswith: 'C:\$WinREAgent\Scratch\'
filter_optional_avira:
    Image|contains|all:
        - '\temp\is-'
        - '\avira_system_speedup.tmp'

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
ImageeqC:\Windows\ImmersiveControlPanel\SystemSettings.exeexcludes:Image field:"Image" value:"C:\Windows\ImmersiveControlPanel\SystemSettings.exe"
ImageeqC:\Windows\explorer.exeexcludes:Image field:"Image" value:"C:\Windows\explorer.exe"
Imageis_null(no value, null check)excludes:Image
Imagestarts_withC:\Program Files (x86)\excludes:Image field:"Image" value:"C:\Program Files (x86)\"
Imagestarts_withC:\Program Files\excludes:Image field:"Image" value:"C:\Program Files\"
Imagestarts_withC:\ProgramData\Package Cache\{excludes:Image field:"Image" value:"C:\ProgramData\Package Cache\{"
Imagestarts_withC:\Windows\SysWOW64\excludes:Image field:"Image" value:"C:\Windows\SysWOW64\"
Imagestarts_withC:\Windows\System32\excludes:Image field:"Image" value:"C:\Windows\System32\"
Imagestarts_withC:\Windows\Temp\{excludes:Image field:"Image" value:"C:\Windows\Temp\{"
Imagestarts_withC:\Windows\WinSxS\excludes:Image field:"Image" value:"C:\Windows\WinSxS\"
Imagematch\avira_system_speedup.tmpexcludes:Image field:"Image" value:"\avira_system_speedup.tmp"
Imagematch\temp\is-excludes:Image field:"Image" value:"\temp\is-"
Imagestarts_withC:\$WinREAgent\Scratch\excludes:Image field:"Image" value:"C:\$WinREAgent\Scratch\"

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
ImageLoadedends_with
  • \vsstrace.dll corpus 2 (sigma 2)
field:"ImageLoaded" kind:ends_with value:"\vsstrace.dll"