Windows reg.exe Direct Modification of Registry Autostart Extensibility Keys (ASEP)

Flags reg.exe adding registry autostart (ASEP) entries under common Run/Winlogon/Policy paths.

FreeUnreviewedSigmamediumv1

windows-reg-exe-direct-modification-of-registry-autostart-extensibility-keys-ase-24357373

title: Windows reg.exe Direct Modification of Registry Autostart Extensibility Keys (ASEP)
id: edd69b40-badb-4092-a981-4c5dced2e7b0
status: test
description: This rule identifies use of reg.exe with an add operation targeting common Windows autostart persistence registry paths associated with ASEP. Attackers use these registry locations to establish or modify programs that execute automatically at user logon or system events for persistence and potential privilege escalation. Telemetry required includes process creation details, specifically the executable identity (reg.exe) and the full command line containing both the add verb and matching registry key strings.
references:
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1547.001/T1547.001.md
  - https://github.com/HackTricks-wiki/hacktricks/blob/e4c7b21b8f36c97c35b7c622732b38a189ce18f7/src/windows-hardening/windows-local-privilege-escalation/privilege-escalation-with-autorun-binaries.md
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_reg_direct_asep_registry_keys_modification.yml
author: Victor Sergeev, Daniil Yugoslavskiy, oscd.community, Swachchhanda Shrawan Poudel (Nextron Systems), Huntrule Team
date: 2019-10-25
modified: 2026-01-05
tags:
  - attack.privilege-escalation
  - attack.persistence
  - attack.t1547.001
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    - Image|endswith: \reg.exe
    - OriginalFileName: reg.exe
  selection_cli_add:
    CommandLine|contains: add
  selection_cli_keys:
    CommandLine|contains:
      - \software\Microsoft\Windows\CurrentVersion\Run
      - \software\WOW6432Node\Microsoft\Windows\CurrentVersion\Run
      - \software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
      - \software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit
      - \software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell
      - \software\Microsoft\Windows NT\CurrentVersion\Windows
      - \system\CurrentControlSet\Control\SafeBoot\AlternateShell
  condition: all of selection_*
falsepositives:
  - Legitimate software automatically (mostly, during installation) sets up autorun keys for legitimate reasons.
  - Legitimate administrator sets up autorun keys for legitimate reasons.
  - Discord
level: medium
license: DRL-1.1
related:
  - id: 24357373-078f-44ed-9ac4-6d334a668a11
    type: derived

What it detects

This rule identifies use of reg.exe with an add operation targeting common Windows autostart persistence registry paths associated with ASEP. Attackers use these registry locations to establish or modify programs that execute automatically at user logon or system events for persistence and potential privilege escalation. Telemetry required includes process creation details, specifically the executable identity (reg.exe) and the full command line containing both the add verb and matching registry key strings.

Known false positives

Legitimate software automatically (mostly, during installation) sets up autorun keys for legitimate reasons.
Legitimate administrator sets up autorun keys for legitimate reasons.
Discord

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.