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Newest: 2.0.2
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Active Rule
Rundll32.EXE Calling DllRegisterServer Export Function Explicitly
Target Profile
Splunk
Splunk SPL & tstats data model queries
Format Mode
Default
Plain SPL queries
Conversion Output
Rundll32.EXE Calling DllRegisterServer Export Function Explicitly
Using Splunk · Default · sigma-cli 2.0.2
Translation controls
Adjust the rule on the left, then regenerate when you want a fresh backend-native query.
BackendSplunkFormatDefaultVersion2.0.2
title: Rundll32.EXE Calling DllRegisterServer Export Function Explicitly
id: d81a9fc6-55db-4461-b962-0e78fea5b0ad
related:
- id: 2569ed8c-1147-498a-9b8c-2ad3656b10ed # Renamed rundll32
type: similar
status: test
description: |
Detects when the DLL export function 'DllRegisterServer' is called in the commandline by Rundll32 explicitly where the DLL is located in a non-standard path.
references:
- https://thedfirreport.com/2023/08/28/html-smuggling-leads-to-domain-wide-ransomware/
- https://www.virustotal.com/gui/file/94816439312563db982cd038cf77cbc5ef4c7003e3edee86e2b0f99e675ed4ed/behavior
- https://learn.microsoft.com/en-us/windows/win32/api/olectl/nf-olectl-dllregisterserver
author: Andreas Braathen (mnemonic.io)
date: 2023-10-17
tags:
- attack.defense-evasion
- attack.t1218
- detection.threat-hunting
logsource:
category: process_creation
product: windows
detection:
selection_image:
- Image|endswith: '\rundll32.exe'
- OriginalFileName: 'RUNDLL32.EXE'
selection_cmdline:
CommandLine|contains: 'DllRegisterServer'
filter_main_legit_paths:
CommandLine|contains:
- ':\Program Files (x86)'
- ':\Program Files\'
- ':\Windows\System32\'
- ':\Windows\SysWOW64\'
condition: all of selection_* and not 1 of filter_main_*
falsepositives:
- Legitimate usage as part of application installation, but less likely from e.g. temporary paths.
- Not every instance is considered malicious, but this rule will capture the malicious usages.
level: medium
CLI command
Copy the exact command to reproduce this translation locally.
sigma convert --without-pipeline -t splunk -f default rules-threat-hunting/windows/process_creation/proc_creation_win_rundll32_dllregisterserver.yml