Suspicious Advpack Call Via Rundll32.EXE

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

Detects execution of "rundll32" calling "advpack.dll" with potential obfuscated ordinal calls in order to leverage the "RegisterOCX" function

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	No specific technique

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Suspicious Advpack Call Via Rundll32.EXE
id: a1473adb-5338-4a20-b4c3-126763e2d3d3
status: test
description: Detects execution of "rundll32" calling "advpack.dll" with potential obfuscated ordinal calls in order to leverage the "RegisterOCX" function
references:
    - https://twitter.com/Hexacorn/status/1224848930795552769
    - http://www.hexacorn.com/blog/2020/02/05/stay-positive-lolbins-not/
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2023-05-17
tags:
    - attack.stealth
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
        - CommandLine|contains: 'rundll32'
    selection_cli_dll:
        CommandLine|contains: 'advpack'
    selection_cli_ordinal:
        - CommandLine|contains|all:
              - '#+'
              - '12'
        - CommandLine|contains: '#-'
    condition: all of selection_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\rundll32.exe'
    - OriginalFileName: 'RUNDLL32.EXE'
    - CommandLine|contains: 'rundll32'

Stage 2: `selection_cli_dll`

selection_cli_dll:
    CommandLine|contains: 'advpack'

Stage 3: `selection_cli_ordinal`

selection_cli_ordinal:
    - CommandLine|contains|all:
          - '#+'
          - '12'
    - CommandLine|contains: '#-'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`#+` corpus 4 (sigma 3, chronicle 1) `#-` corpus 4 (sigma 3, chronicle 1) `12` `advpack` `rundll32` corpus 26 (sigma 23, chronicle 2, kusto 1)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\rundll32.exe` corpus 94 (sigma 94)	`field:"Image" kind:ends_with value:"\rundll32.exe"`
`OriginalFileName`	eq	`RUNDLL32.EXE` corpus 78 (sigma 35, elastic 22, splunk 21)	`field:"OriginalFileName" kind:eq value:"RUNDLL32.EXE"`

Suspicious Advpack Call Via Rundll32.EXE

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli_dll

Stage 3: selection_cli_ordinal

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli_dll`

Stage 3: `selection_cli_ordinal`