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Windows Image Load Executes Unsigned Thor Scanner Binaries

Alerts on thor.exe/thor64.exe image loads on Windows where the Authenticode signature is missing or not from Nextron Systems.

FreeUnreviewedSigmahighv1
title: Windows Image Load Executes Unsigned Thor Scanner Binaries
id: 737ec172-2b11-4c9f-bfa7-8c6eeba37ca4
status: stable
description: This rule flags when a Windows process loads and attempts to execute a thor.exe or thor64.exe that is not signed by Nextron Systems GmbH. Attackers may use lookalike or modified binaries to run unauthorized tooling while bypassing expected code signing. The detection relies on image load telemetry and Authenticode signature metadata, specifically image paths ending in thor.exe/thor64.exe and signature fields indicating it is not a valid, Nextron Systems GmbH-signed binary.
references:
  - Internal Research
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/image_load/image_load_thor_unsigned_execution.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2023-10-29
tags:
  - attack.privilege-escalation
  - attack.persistence
  - attack.execution
  - attack.stealth
  - attack.t1574.001
logsource:
  category: image_load
  product: windows
detection:
  selection:
    Image|endswith:
      - \thor.exe
      - \thor64.exe
    ImageLoaded|endswith:
      - \thor.exe
      - \thor64.exe
  filter_main:
    Signed: "true"
    SignatureStatus: valid
    Signature: Nextron Systems GmbH
  condition: selection and not filter_main
falsepositives:
  - Other legitimate binaries named "thor.exe" that aren't published by Nextron Systems
level: high
license: DRL-1.1
related:
  - id: ea5c131b-380d-49f9-aeb3-920694da4d4b
    type: derived

What it detects

This rule flags when a Windows process loads and attempts to execute a thor.exe or thor64.exe that is not signed by Nextron Systems GmbH. Attackers may use lookalike or modified binaries to run unauthorized tooling while bypassing expected code signing. The detection relies on image load telemetry and Authenticode signature metadata, specifically image paths ending in thor.exe/thor64.exe and signature fields indicating it is not a valid, Nextron Systems GmbH-signed binary.

Known false positives

  • Other legitimate binaries named "thor.exe" that aren't published by Nextron Systems

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