Formbook Process Creation

testhigh

log source: windows · process_creationauthor Florian Roth (Nextron Systems), oscd.community, Jonhnathan Ribeirodate 2019-09-30

description

What this is, in brief.

Detects Formbook like process executions that inject code into a set of files in the System32 folder, which executes a special command command line to delete the dropper from the AppData Temp folder. We avoid false positives by excluding all parent process with command line parameters.

rule source (YAML)

title: Formbook Process Creation
id: 032f5fb3-d959-41a5-9263-4173c802dc2b
status: test
description: Detects Formbook like process executions that inject code into a set of files in the System32 folder, which executes a special command command line to delete the dropper from the AppData Temp folder. We avoid false positives by excluding all parent process with command line parameters.
references:
    - https://inquest.net/blog/2018/06/22/a-look-at-formbook-stealer
    - https://app.any.run/tasks/388d5802-aa48-4826-b069-250420504758/
    - https://app.any.run/tasks/8e22486b-5edc-4cef-821c-373e945f296c/
    - https://app.any.run/tasks/62bb01ae-25a4-4180-b278-8e464a90b8d7/
author: Florian Roth (Nextron Systems), oscd.community, Jonhnathan Ribeiro
date: 2019-09-30
modified: 2022-10-06
tags:
    - attack.resource-development
    - attack.t1587.001
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection1:
        # Parent command line should not contain a space value
        # This avoids false positives not caused by process injection
        # e.g. wscript.exe /B sysmon-install.vbs
        ParentCommandLine|startswith:
            - 'C:\Windows\System32\'
            - 'C:\Windows\SysWOW64\'
        ParentCommandLine|endswith: '.exe'
    selection2:
        - CommandLine|contains|all:
              - '/c'
              - 'del'
              - 'C:\Users\'
              - '\AppData\Local\Temp\'
        - CommandLine|contains|all:
              - '/c'
              - 'del'
              - 'C:\Users\'
              - '\Desktop\'
        - CommandLine|contains|all:
              - '/C'
              - 'type nul >'
              - 'C:\Users\'
              - '\Desktop\'
    selection3:
        CommandLine|endswith: '.exe'
    condition: all of selection*
falsepositives:
    - Unknown
level: high

detects techniques (1)

ATT&CK techniques this enables or maps to.

T1587.001Malware

references

External citations — patches, advisories, analysis.