Detection rules › Sigma
Scripting/CommandLine Process Spawned Regsvr32
Detects various command line and scripting engines/processes such as "PowerShell", "Wscript", "Cmd", etc. spawning a "regsvr32" instance.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1218.010 System Binary Proxy Execution: Regsvr32 |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
title: Scripting/CommandLine Process Spawned Regsvr32
id: ab37a6ec-6068-432b-a64e-2c7bf95b1d22
related:
- id: 8e2b24c9-4add-46a0-b4bb-0057b4e6187d
type: obsolete
status: test
description: Detects various command line and scripting engines/processes such as "PowerShell", "Wscript", "Cmd", etc. spawning a "regsvr32" instance.
references:
- https://web.archive.org/web/20171001085340/https://subt0x10.blogspot.com/2017/04/bypass-application-whitelisting-script.html
- https://app.any.run/tasks/34221348-072d-4b70-93f3-aa71f6ebecad/
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2023-05-26
tags:
- attack.stealth
- attack.t1218.010
logsource:
category: process_creation
product: windows
detection:
selection:
ParentImage|endswith:
- '\cmd.exe'
- '\cscript.exe'
- '\mshta.exe'
- '\powershell_ise.exe'
- '\powershell.exe'
- '\pwsh.exe'
- '\wscript.exe'
Image|endswith: '\regsvr32.exe'
filter_main_rpcproxy:
ParentImage: C:\Windows\System32\cmd.exe
CommandLine|endswith: ' /s C:\Windows\System32\RpcProxy\RpcProxy.dll'
condition: selection and not 1 of filter_main_*
falsepositives:
- Legitimate ".bat", ".hta", ".ps1" or ".vbs" scripts leverage legitimately often. Apply additional filter and exclusions as necessary
- Some legitimate Windows services
level: medium # Can be reduced to low if you experience a ton of FP
Stages and Predicates
Stage 0: condition
selection and not 1 of filter_main_*Stage 1: selection
selection:
ParentImage|endswith:
- '\cmd.exe'
- '\cscript.exe'
- '\mshta.exe'
- '\powershell_ise.exe'
- '\powershell.exe'
- '\pwsh.exe'
- '\wscript.exe'
Image|endswith: '\regsvr32.exe'
Stage 2: not filter_main_rpcproxy
filter_main_rpcproxy:
ParentImage: C:\Windows\System32\cmd.exe
CommandLine|endswith: ' /s C:\Windows\System32\RpcProxy\RpcProxy.dll'
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
CommandLine | ends_with | /s C:\Windows\System32\RpcProxy\RpcProxy.dll |
ParentImage | eq | C:\Windows\System32\cmd.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.
| Field | Kind | Values |
|---|---|---|
Image | ends_with |
|
ParentImage | ends_with |
|