Detection rules › Sigma

Potentially Suspicious Execution From Parent Process In Public Folder

Severity
high
Author
Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
Source
upstream

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

TacticTechniques
ExecutionT1059 Command and Scripting Interpreter
Defense EvasionT1564 Hide Artifacts

Event coverage

ProviderEvent IDTitle
Sysmon1Process creation
Security-Auditing4688A new process has been created.

Stages and Predicates

Stage 1: all of selection_parent

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

Stage 2: all of selection_child

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

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 5 (sigma 5)
  • certutil corpus 5 (sigma 5)
  • cscript corpus 12 (sigma 12)
  • mshta corpus 11 (sigma 11)
  • powershell corpus 16 (sigma 16)
  • regsvr32 corpus 11 (sigma 11)
  • rundll32 corpus 19 (sigma 19)
  • wscript corpus 12 (sigma 12)
Imageends_with
  • \bitsadmin.exe corpus 23 (sigma 23)
  • \certutil.exe corpus 34 (sigma 34)
  • \cmd.exe corpus 92 (sigma 92)
  • \cscript.exe corpus 64 (sigma 64)
  • \mshta.exe corpus 57 (sigma 57)
  • \powershell.exe corpus 143 (sigma 143)
  • \pwsh.exe corpus 140 (sigma 140)
  • \regsvr32.exe corpus 57 (sigma 57)
  • \rundll32.exe corpus 76 (sigma 76)
  • \wscript.exe corpus 64 (sigma 64)
ParentImagematch
  • :\Users\Public\ corpus 2 (sigma 2)