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Detection rules › Sigma

Potential Suspicious Registry File Imported Via Reg.EXE

Status
test
Severity
medium
Log source
product windows, category process_creation
Author
frack113, Nasreddine Bencherchali
Source
github.com/SigmaHQ/sigma

Detects the import of '.reg' files from suspicious paths using the 'reg.exe' utility

MITRE ATT&CK coverage

TacticTechniques
PersistenceT1112 Modify Registry
Defense ImpairmentT1112 Modify Registry

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Potential Suspicious Registry File Imported Via Reg.EXE
id: 62e0298b-e994-4189-bc87-bc699aa62d97
related:
    - id: 73bba97f-a82d-42ce-b315-9182e76c57b1
      type: derived
status: test
description: Detects the import of '.reg' files from suspicious paths using the 'reg.exe' utility
references:
    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/reg-import
author: frack113, Nasreddine Bencherchali
date: 2022-08-01
modified: 2023-02-05
tags:
    - attack.persistence
    - attack.defense-impairment
    - attack.t1112
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\reg.exe'
        - OriginalFileName: 'reg.exe'
    selection_cli:
        CommandLine|contains: ' import '
    selection_paths:
        CommandLine|contains:
            - 'C:\Users\'
            - '%temp%'
            - '%tmp%'
            - '%appdata%'
            - '\AppData\Local\Temp\'
            - 'C:\Windows\Temp\'
            - 'C:\ProgramData\'
    condition: all of selection_*
falsepositives:
    - Legitimate import of keys
level: medium

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: ' import '

Stage 3: selection_paths

selection_paths:
    CommandLine|contains:
        - 'C:\Users\'
        - '%temp%'
        - '%tmp%'
        - '%appdata%'
        - '\AppData\Local\Temp\'
        - 'C:\Windows\Temp\'
        - 'C:\ProgramData\'

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
  • import
  • %appdata% corpus 13 (sigma 11, chronicle 2)
  • %temp% corpus 16 (sigma 13, chronicle 2, kusto 1)
  • %tmp% corpus 15 (sigma 13, chronicle 2)
  • C:\ProgramData\ corpus 6 (sigma 6)
  • C:\Users\ corpus 7 (sigma 7)
  • C:\Windows\Temp\ corpus 7 (sigma 7)
  • \AppData\Local\Temp\ corpus 26 (sigma 26)
Imageends_with
  • \reg.exe corpus 58 (sigma 58)
OriginalFileNameeq
  • reg.exe corpus 42 (sigma 32, splunk 8, elastic 2)