Windows Process Creation: regsvr32 Invoked to Load .ocx from AppData Roaming
Flags regsvr32 /s /i loading an .ocx from AppData\Roaming on Windows, a stealthy code-loading technique.
- Product
- windows
- Category
- process_creation
- Author
- Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
- Published
- 2020-07-10
- Updated
- 2026-07-31
ATT&CK techniques
Defense EvasionRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule flags Windows process creation events where regsvr32 is executed with parameters that include /s /i, a path under AppData\Roaming\, and a .ocx extension. That pattern is consistent with signed-binary execution used to load and run external component files from user-writable locations. The detection relies on process command-line telemetry containing these specific substrings.
Reporting behind it
- welivesecurity.comhttps://www.welivesecurity.com/2020/07/09/more-evil-deep-look-evilnum-toolset/
- app.any.runhttps://app.any.run/tasks/33d37fdf-158d-4930-aa68-813e1d5eb8ba/
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2020/TA/Evilnum/proc_creation_win_apt_evilnum_jul20.yml
Changelog
v5- v5Candidate ingested via manual entry.2026-07-31
- v4Candidate ingested via manual entry.2026-07-31
- v3Candidate ingested via manual entry.2026-07-31
- v2Candidate ingested via manual entry.2026-07-31
- v1No changelog recorded for this version.2026-07-30
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
title: "Windows Process Creation: regsvr32 Invoked to Load .ocx from AppData Roaming"
id: 5094b28c-8c8c-478c-9842-0afdbb24788c
status: test
description: This rule flags Windows process creation events where regsvr32 is executed with parameters that include /s /i, a path under AppData\Roaming\, and a .ocx extension. That pattern is consistent with signed-binary execution used to load and run external component files from user-writable locations. The detection relies on process command-line telemetry containing these specific substrings.
references:
- https://www.welivesecurity.com/2020/07/09/more-evil-deep-look-evilnum-toolset/
- https://app.any.run/tasks/33d37fdf-158d-4930-aa68-813e1d5eb8ba/
- https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2020/TA/Evilnum/proc_creation_win_apt_evilnum_jul20.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2020-07-10
modified: 2023-03-09
tags:
- attack.stealth
- attack.t1218.011
- detection.emerging-threats
logsource:
category: process_creation
product: windows
detection:
selection:
CommandLine|contains|all:
- regsvr32
- /s
- /i
- \AppData\Roaming\
- .ocx
condition: selection
falsepositives:
- Unknown
level: critical
license: DRL-1.1
related:
- id: 8acf3cfa-1e8c-4099-83de-a0c4038e18f0
type: derived