Network Connection Initiated By AddinUtil.EXE

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

Detects a network connection initiated by the Add-In deployment cache updating utility "AddInutil.exe". This could indicate a potential command and control communication as this tool doesn't usually initiate network activity.

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218` System Binary Proxy Execution

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 3: Network connection

Rule body

title: Network Connection Initiated By AddinUtil.EXE
id: 5205613d-2a63-4412-a895-3a2458b587b3
status: test
description: |
    Detects a network connection initiated by the Add-In deployment cache updating utility "AddInutil.exe".
    This could indicate a potential command and control communication as this tool doesn't usually initiate network activity.
references:
    - https://www.blue-prints.blog/content/blog/posts/lolbin/addinutil-lolbas.html
author: Michael McKinley (@McKinleyMike), Tony Latteri (@TheLatteri)
date: 2023-09-18
modified: 2024-07-16
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Initiated: 'true'
        Image|endswith: '\addinutil.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    Initiated: 'true'
    Image|endswith: '\addinutil.exe'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Image`	ends_with	`\addinutil.exe` corpus 4 (sigma 4)	`field:"Image" kind:ends_with value:"\addinutil.exe"`
`Initiated`	eq	`true` corpus 50 (sigma 50)	`field:"Initiated" kind:eq value:"true"`