Detection rules › Sigma

Uncommon Child Process Of AddinUtil.EXE

Status
test
Severity
medium
Log source
product windows, category process_creation
Author
Michael McKinley (@McKinleyMike), Tony Latteri (@TheLatteri)
Source
github.com/SigmaHQ/sigma

Detects uncommon child processes of the Add-In deployment cache updating utility (AddInutil.exe) which could be a sign of potential abuse of the binary to proxy execution via a custom Addins.Store payload.

MITRE ATT&CK coverage

Event coverage

Rule body yaml

title: Uncommon Child Process Of AddinUtil.EXE
id: b5746143-59d6-4603-8d06-acbd60e166ee
status: test
description: |
    Detects uncommon child processes of the Add-In deployment cache updating utility (AddInutil.exe) which could be a sign of potential abuse of the binary to proxy execution via a custom Addins.Store payload.
references:
    - https://www.blue-prints.blog/content/blog/posts/lolbin/addinutil-lolbas.html
author: Michael McKinley (@McKinleyMike), Tony Latteri (@TheLatteri)
date: 2023-09-18
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\addinutil.exe'
    filter_main_werfault:
        Image|endswith:
            - ':\Windows\System32\conhost.exe'
            - ':\Windows\System32\werfault.exe'
            - ':\Windows\SysWOW64\werfault.exe'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_*

Stage 1: selection

selection:
    ParentImage|endswith: '\addinutil.exe'

Stage 2: not filter_main_werfault

filter_main_werfault:
    Image|endswith:
        - ':\Windows\System32\conhost.exe'
        - ':\Windows\System32\werfault.exe'
        - ':\Windows\SysWOW64\werfault.exe'

Exclusions

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

FieldKindExcluded values
Imageends_with:\Windows\SysWOW64\werfault.exe
Imageends_with:\Windows\System32\conhost.exe
Imageends_with:\Windows\System32\werfault.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
ParentImageends_with
  • \addinutil.exe