Malware Shellcode in Verclsid Target Process

SIGMA detection rule by John Lambert (tech), Florian Roth (Nextron Systems) · NOASSERTION

Detects a process access to verclsid.exe that injects shellcode from a Microsoft Office application / VBA macro

title: Malware Shellcode in Verclsid Target Process
id: b7967e22-3d7e-409b-9ed5-cdae3f9243a1
status: test
description: Detects a process access to verclsid.exe that injects shellcode from a Microsoft Office application / VBA macro
references:
    - https://twitter.com/JohnLaTwC/status/837743453039534080
author: John Lambert (tech), Florian Roth (Nextron Systems)
date: 2017-03-04
modified: 2021-11-27
tags:
    - attack.privilege-escalation
    - attack.stealth
    - attack.t1055
    - detection.emerging-threats
logsource:
    category: process_access
    product: windows
    definition: 'Requirements: The following config is required to generate the necessary Event ID 10 Process Access events: <ProcessAccess onmatch="include"><CallTrace condition="contains">VBE7.DLL</CallTrace></ProcessAccess><ProcessAccess onmatch="exclude"><CallTrace condition="excludes">UNKNOWN</CallTrace></ProcessAccess>'
detection:
    selection_target:
        TargetImage|endswith: '\verclsid.exe'
        GrantedAccess: '0x1FFFFF'
    selection_calltrace_1:
        CallTrace|contains|all:
            - '|UNKNOWN('
            - 'VBE7.DLL'
    selection_calltrace_2:
        SourceImage|contains: '\Microsoft Office\'
        CallTrace|contains: '|UNKNOWN'
    condition: selection_target and 1 of selection_calltrace_*
falsepositives:
    - Unknown
level: high

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

e93d29b8-246f-4c36-8bf8-354b78f086e2

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This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

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