Detection rules › Sigma

Forest Blizzard APT - Process Creation Activity

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

Detects the execution of specific processes and command line combination. These were seen being created by Forest Blizzard as described by MSFT.

MITRE ATT&CK coverage

TacticTechniques
ExecutionNo specific technique
StealthNo specific technique

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation

Rule body

title: Forest Blizzard APT - Process Creation Activity
id: 07db928c-8632-488e-ac7d-3db847489175
status: experimental
description: |
    Detects the execution of specific processes and command line combination.
    These were seen being created by Forest Blizzard as described by MSFT.
references:
    - https://www.microsoft.com/en-us/security/blog/2024/04/22/analyzing-forest-blizzards-custom-post-compromise-tool-for-exploiting-cve-2022-38028-to-obtain-credentials/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2024-04-23
modified: 2025-01-22
tags:
    - attack.execution
    - detection.emerging-threats
    - attack.stealth
logsource:
    category: process_creation
    product: windows
detection:
    selection_hashes:
        Hashes|contains:
            - 'SHA256=6b311c0a977d21e772ac4e99762234da852bbf84293386fbe78622a96c0b052f'
            - 'SHA256=c60ead92cd376b689d1b4450f2578b36ea0bf64f3963cfa5546279fa4424c2a5'
    selection_schtasks_create:
        Image|endswith: '\schtasks.exe'
        CommandLine|contains|all:
            - 'Create'
            - '/RU'
            - 'SYSTEM'
            - '\Microsoft\Windows\WinSrv'
        CommandLine|contains:
            - 'servtask.bat'
            - 'execute.bat'
            - 'doit.bat'
    selection_schtasks_delete:
        Image|endswith: '\schtasks.exe'
        CommandLine|contains|all:
            - 'Delete'
            - '/F '
            - '\Microsoft\Windows\WinSrv'
    selection_powershell:
        CommandLine|contains|all:
            - 'Get-ChildItem'
            - '.save'
            - 'Compress-Archive -DestinationPath C:\ProgramData\'
    condition: 1 of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

1 of selection_*

Stage 1: selection_hashes

selection_hashes:
    Hashes|contains:
        - 'SHA256=6b311c0a977d21e772ac4e99762234da852bbf84293386fbe78622a96c0b052f'
        - 'SHA256=c60ead92cd376b689d1b4450f2578b36ea0bf64f3963cfa5546279fa4424c2a5'

Stage 2: selection_schtasks_create

selection_schtasks_create:
    Image|endswith: '\schtasks.exe'
    CommandLine|contains|all:
        - 'Create'
        - '/RU'
        - 'SYSTEM'
        - '\Microsoft\Windows\WinSrv'
    CommandLine|contains:
        - 'servtask.bat'
        - 'execute.bat'
        - 'doit.bat'

Stage 3: selection_schtasks_delete

selection_schtasks_delete:
    Image|endswith: '\schtasks.exe'
    CommandLine|contains|all:
        - 'Delete'
        - '/F '
        - '\Microsoft\Windows\WinSrv'

Stage 4: selection_powershell

selection_powershell:
    CommandLine|contains|all:
        - 'Get-ChildItem'
        - '.save'
        - 'Compress-Archive -DestinationPath C:\ProgramData\'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • .save
  • /F corpus 3 (sigma 3)
  • /RU corpus 3 (sigma 3)
  • Compress-Archive -DestinationPath C:\ProgramData\
  • Create corpus 29 (sigma 17, splunk 7, elastic 5)
  • Delete corpus 31 (sigma 16, elastic 8, splunk 6, kusto 1)
  • Get-ChildItem
  • SYSTEM corpus 9 (sigma 4, splunk 3, elastic 2)
  • \Microsoft\Windows\WinSrv
  • doit.bat
  • execute.bat
  • servtask.bat
field:"CommandLine" kind:match
Hashesmatch
  • SHA256=6b311c0a977d21e772ac4e99762234da852bbf84293386fbe78622a96c0b052f
  • SHA256=c60ead92cd376b689d1b4450f2578b36ea0bf64f3963cfa5546279fa4424c2a5
field:"Hashes" kind:match
Imageends_with
  • \schtasks.exe corpus 55 (sigma 55)
field:"Image" kind:ends_with value:"\schtasks.exe"