Detection rules › Sigma

Process Execution From A Potentially Suspicious Folder

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

Detects a potentially suspicious execution from an uncommon folder.

MITRE ATT&CK coverage

TacticTechniques
StealthT1036 Masquerading

Event coverage

Rule body yaml

title: Process Execution From A Potentially Suspicious Folder
id: 3dfd06d2-eaf4-4532-9555-68aca59f57c4
status: test
description: Detects a potentially suspicious execution from an uncommon folder.
references:
    - https://github.com/mbevilacqua/appcompatprocessor/blob/6c847937c5a836e2ce2fe2b915f213c345a3c389/AppCompatSearch.txt
    - https://www.secureworks.com/research/bronze-butler-targets-japanese-businesses
    - https://www.crowdstrike.com/resources/reports/2019-crowdstrike-global-threat-report/
    - https://github.com/ThreatHuntingProject/ThreatHunting/blob/cb22598bb70651f88e0285abc8d835757d2cb596/hunts/suspicious_process_creation_via_windows_event_logs.md
author: Florian Roth (Nextron Systems), Tim Shelton
date: 2019-01-16
modified: 2024-07-12
tags:
    - attack.stealth
    - attack.t1036
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|contains:
            - ':\Perflogs\'
            - ':\Users\All Users\'
            - ':\Users\Default\'
            - ':\Users\NetworkService\'
            - ':\Windows\addins\'
            - ':\Windows\debug\'
            - ':\Windows\Fonts\'
            - ':\Windows\Help\'
            - ':\Windows\IME\'
            - ':\Windows\Media\'
            - ':\Windows\repair\'
            - ':\Windows\security\'
            - ':\Windows\System32\Tasks\'
            - ':\Windows\Tasks\'
            - '$Recycle.bin'
            - '\config\systemprofile\'
            - '\Intel\Logs\'
            - '\RSA\MachineKeys\'
    filter_optional_ibm:
        Image|startswith: 'C:\Users\Public\IBM\ClientSolutions\Start_Programs\'
    filter_optional_citrix:
        Image|startswith: 'C:\Windows\SysWOW64\config\systemprofile\Citrix\UpdaterBinaries\'
        Image|endswith: '\CitrixReceiverUpdater.exe'
    condition: selection and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_optional_*

Stage 1: selection

selection:
    Image|contains:
        - ':\Perflogs\'
        - ':\Users\All Users\'
        - ':\Users\Default\'
        - ':\Users\NetworkService\'
        - ':\Windows\addins\'
        - ':\Windows\debug\'
        - ':\Windows\Fonts\'
        - ':\Windows\Help\'
        - ':\Windows\IME\'
        - ':\Windows\Media\'
        - ':\Windows\repair\'
        - ':\Windows\security\'
        - ':\Windows\System32\Tasks\'
        - ':\Windows\Tasks\'
        - '$Recycle.bin'
        - '\config\systemprofile\'
        - '\Intel\Logs\'
        - '\RSA\MachineKeys\'

Stage 2: not filter_optional_*

filter_optional_ibm:
    Image|startswith: 'C:\Users\Public\IBM\ClientSolutions\Start_Programs\'
filter_optional_citrix:
    Image|startswith: 'C:\Windows\SysWOW64\config\systemprofile\Citrix\UpdaterBinaries\'
    Image|endswith: '\CitrixReceiverUpdater.exe'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
Imageends_with\CitrixReceiverUpdater.exe
Imagestarts_withC:\Windows\SysWOW64\config\systemprofile\Citrix\UpdaterBinaries\
Imagestarts_withC:\Users\Public\IBM\ClientSolutions\Start_Programs\

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
Imagematch
  • $Recycle.bin
  • :\Perflogs\ corpus 10 (sigma 10)
  • :\Users\All Users\
  • :\Users\Default\ corpus 3 (sigma 3)
  • :\Users\NetworkService\
  • :\Windows\Fonts\ corpus 3 (sigma 3)
  • :\Windows\Help\
  • :\Windows\IME\ corpus 3 (sigma 3)
  • :\Windows\Media\
  • :\Windows\System32\Tasks\ corpus 4 (sigma 4)
  • :\Windows\Tasks\ corpus 5 (sigma 5)
  • :\Windows\addins\
  • :\Windows\debug\
  • :\Windows\repair\
  • :\Windows\security\
  • \Intel\Logs\
  • \RSA\MachineKeys\
  • \config\systemprofile\ corpus 4 (sigma 4)