Detection rules › Sigma

Potentially Suspicious Execution From Parent Process In Public Folder

Status
test
Severity
high
Log source
product windows, category process_creation
Author
Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects a potentially suspicious execution of a parent process located in the "\Users\Public" folder executing a child process containing references to shell or scripting binaries and commandlines.

MITRE ATT&CK coverage

Event coverage

Rule body yaml

title: Potentially Suspicious Execution From Parent Process In Public Folder
id: 69bd9b97-2be2-41b6-9816-fb08757a4d1a
status: test
description: |
    Detects a potentially suspicious execution of a parent process located in the "\Users\Public" folder executing a child process containing references to shell or scripting binaries and commandlines.
references:
    - https://redcanary.com/blog/blackbyte-ransomware/
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2022-02-25
modified: 2024-07-12
tags:
    - attack.execution
    - attack.stealth
    - attack.t1564
    - attack.t1059
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|contains: ':\Users\Public\'
    selection_child:
        - Image|endswith:
              - '\bitsadmin.exe'
              - '\certutil.exe'
              - '\cmd.exe'
              - '\cscript.exe'
              - '\mshta.exe'
              - '\powershell.exe'
              - '\pwsh.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
              - '\wscript.exe'
        - CommandLine|contains:
              - 'bitsadmin'
              - 'certutil'
              - 'cscript'
              - 'mshta'
              - 'powershell'
              - 'regsvr32'
              - 'rundll32'
              - 'wscript'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_parent

selection_parent:
    ParentImage|contains: ':\Users\Public\'

Stage 2: selection_child

selection_child:
    - Image|endswith:
          - '\bitsadmin.exe'
          - '\certutil.exe'
          - '\cmd.exe'
          - '\cscript.exe'
          - '\mshta.exe'
          - '\powershell.exe'
          - '\pwsh.exe'
          - '\regsvr32.exe'
          - '\rundll32.exe'
          - '\wscript.exe'
    - CommandLine|contains:
          - 'bitsadmin'
          - 'certutil'
          - 'cscript'
          - 'mshta'
          - 'powershell'
          - 'regsvr32'
          - 'rundll32'
          - 'wscript'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • bitsadmin corpus 10 (sigma 10)
  • certutil corpus 12 (sigma 10, kusto 2)
  • cscript corpus 15 (sigma 15)
  • mshta corpus 14 (sigma 14)
  • powershell corpus 25 (sigma 24, chronicle 1)
  • regsvr32 corpus 15 (sigma 15)
  • rundll32 corpus 26 (sigma 23, chronicle 2, kusto 1)
  • wscript corpus 16 (sigma 16)
Imageends_with
  • \bitsadmin.exe corpus 29 (sigma 29)
  • \certutil.exe corpus 43 (sigma 43)
  • \cmd.exe corpus 130 (sigma 130)
  • \cscript.exe corpus 73 (sigma 73)
  • \mshta.exe corpus 67 (sigma 67)
  • \powershell.exe corpus 182 (sigma 182)
  • \pwsh.exe corpus 168 (sigma 168)
  • \regsvr32.exe corpus 65 (sigma 65)
  • \rundll32.exe corpus 95 (sigma 95)
  • \wscript.exe corpus 75 (sigma 75)
ParentImagematch
  • :\Users\Public\ corpus 2 (sigma 2)