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Detection rules › Sigma

RunMRU Registry Key Deletion

Status
experimental
Severity
high
Log source
product windows, category process_creation
Author
Swachchhanda Shrawan Poudel (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects deletion of the RunMRU registry key, which stores the history of commands executed via the Run dialog. In the clickfix techniques, the phishing lures instruct users to open a run dialog through (Win + R) and execute malicious commands. Adversaries may delete this key to cover their tracks after executing commands.

MITRE ATT&CK coverage

TacticTechniques
StealthT1070.003 Indicator Removal: Clear Command History

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: RunMRU Registry Key Deletion
id: c11aecef-9c37-45a6-9c07-bc0782f963fd
related:
    - id: 3a9b8c1e-5b2e-4f7a-9d1c-2a7f3b6e1c55
      type: similar
status: experimental
description: |
    Detects deletion of the RunMRU registry key, which stores the history of commands executed via the Run dialog.
    In the clickfix techniques, the phishing lures instruct users to open a run dialog through (Win + R) and execute malicious commands.
    Adversaries may delete this key to cover their tracks after executing commands.
references:
    - https://www.zscaler.com/blogs/security-research/coldriver-updates-arsenal-baitswitch-and-simplefix
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-09-25
tags:
    - attack.stealth
    - attack.t1070.003
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\reg.exe'
        - OriginalFileName: 'reg.exe'
    selection_cli:
        CommandLine|contains|all:
            - ' del'
            - '\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\reg.exe'
    - OriginalFileName: 'reg.exe'

Stage 2: selection_cli

selection_cli:
    CommandLine|contains|all:
        - ' del'
        - '\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU'

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.

FieldKindValues
CommandLinematch
  • del corpus 3 (splunk 2, sigma 1)
  • \Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU
Imageends_with
  • \reg.exe corpus 58 (sigma 58)
OriginalFileNameeq
  • reg.exe corpus 42 (sigma 32, splunk 8, elastic 2)