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Execution of known malicious file d9ac9c950e5495c9…

SIGmediumconfidence 76/100generated 2026-10-18

Process image hash tracked by skopnix as tortoiseshell.

Linked actors
Tortoiseshell
False positives
Scoped to one indicator with skopnix confidence 76/100 from 2 independent sources; checked against RFC1918/reserved space, CDN / cloud / scanner ranges and top-site lists (MISP warninglists), GreyNoise when enriched, and skopnix's benign-infrastructure list. Re-validate against last_seen before blocking: infrastructure is re-assigned.

Sigma rule

skopnix-sigma-ioc-sha256-d9ac9c950e5495c9005b04843a40f01fa49d5fd4922-49c65767.ymldownload .yml ↓
title: Skopnix - Execution of known malicious file d9ac9c950e5495c9…
id: 3043fe2c-ccb7-5bf8-a077-1d2cab6467d6
status: experimental
description: Process image hash tracked by skopnix as tortoiseshell.
references:
  - https://skopnix.com/ioc/d9ac9c950e5495c9005b04843a40f01fa49d5fd49226cb5b03a055232ffc36f3
author: skopnix
date: '2026-10-18'
tags:
  - attack.execution
  - attack.t1204.002
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Hashes|contains: SHA256=D9AC9C950E5495C9005B04843A40F01FA49D5FD49226CB5B03A055232FFC36F3
  condition: selection
falsepositives:
  - Legitimate services sharing the address; verify against skopnix confidence + last_seen
level: medium

How to deploy on Sigma

  1. 1.Convert for your SIEM with sigma-cli / pySigma, e.g. sigma convert -t splunk -p sysmon rule.yml.
  2. 2.Run it as a hunt first: every rule ships as status experimental.
  3. 3.Promote to an alert once a week of results is clean on your data.

Check · The processing pipeline must map the logsource (firewall, dns, proxy, webserver, process_creation) to your field names.

References