Stop

Overview

STOP (universally recognized across consumer cybersecurity forums and threat feeds as STOP/Djvu) is the single most prevalent consumer ransomware family in cyber history by raw victim count. Active since late 2018, STOP specifically targets home consumers, remote workers, and small business operators by distributing its payloads through trojanized software cracks, warez torrents, key generators (such as fake KMSPico activators), and pirated media bundles. Once executed on a Windows system, the ransomware attempts to reach its centralized command-and-control servers to obtain an 'Online Key' (a unique public RSA key generated per victim). If the host is disconnected or firewalled from the C2 server, STOP falls back to an embedded hardcoded 'Offline Key' that is shared across thousands of victims. The malware traverses all mounted fixed and removable drives, encrypting victim personal files (documents, images, videos, databases) using high-speed AES-256 encryption and appending unique extension tags (with hundreds of observed variants including .djvu, .stop, .gero, .coot, .tisc, and .peet). In over 60% of modern infections, STOP simultaneously deploys secondary infostealers (such as Vidar or RedLine) to harvest stored browser credentials and cryptocurrency wallets before the ransom note (_readme.txt) is displayed.

Known aliases

Threat reports may refer to this family under multiple names:

• STOP/Djvu
• Djvu Ransomware
• Ransomware:Win32/Stop
• Trojan-Ransom.Win32.Stop
• Djvu

Threat Actor Attribution

Attribution is probabilistic, not a science. Each link below states its confidence level and the evidence behind it.

• STOP Cybercrime Syndicate Medium confidence
  Basis:

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Stop Early Variant

Known Derivatives & Downstream Variants: Djvu · Gero · Peet · Coot · Tisc · Derp

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1056.001: Implement Endpoint Detection and Response (EDR) to monitor for suspicious API calls related to keystroke interception. Enforce Multi-Factor Authentication (MFA) to render stolen passwords useless.
• T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Command & Control (C2) and Network Profile

How this family talks to its operators. C2 traffic can often identify a family even when its code and configuration are hard to analyse. Ports and patterns are historical and change between campaigns, so use them as hunting leads rather than block-only rules.

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• e23b2c93847849e7552eb412854c6020c644d622830f0f35a4d467888b13d2bb
• 378d388656d07d12db9ad358be85233e721669466be9636c138f3ecb53a060d4

Delivery vectors

• cracked_software
• warez_torrents
• youtube_description_links
• fake_activators

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run
• Scheduled Task Creation

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_STOP_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Stop"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "stop" ascii wide nocase
        $s2 = "stop/djvu" ascii wide nocase
        $s3 = "djvu ransomware" ascii wide nocase
        $s4 = "ransomware:win32/stop" ascii wide nocase
        $s5 = "trojan-ransom.win32.stop" ascii wide nocase
        $s6 = "djvu" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Stop (Ransomware) Execution & Triage
id: b0a24041-ccd2-59e5-9786-39c5649943e2
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Stop malware family. Detects volume shadow copy deletion, boot status tampering,
  and recovery inhibition characteristic of modern ransomware operations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/stop
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.ransomware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1486
- attack.t1490
- attack.t1059_003
- attack.t1547_001
- attack.t1083
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \vssadmin.exe
    - \wmic.exe
    - \wbadmin.exe
    - \bcdedit.exe
    CommandLine|contains:
    - delete shadows
    - shadowcopy delete
    - resize shadowstorage
    - recoveryenabled no
    - ignoreallfailures
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: critical

rule MALWARE_WIN_STOP_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Stop tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "stop" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Disconnect the infected computer from local Wi-Fi and Ethernet networks immediately.
2. Examine C:\SystemID\PersonalID.txt to inspect the assigned victim identifier; strings ending in 't1' indicate an Offline Key that is fully decryptable.
3. Run an offline antivirus scan to eradicate co-installed infostealer payloads (Vidar, RedLine) before entering credentials.
4. Change all banking, email, and social media passwords from a clean, separate device.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Never pay the ransom demand via cryptocurrency; STOP operators rarely deliver working keys to consumers.
2. Do not download third-party paid 'decryption tools' from untrusted YouTube channels or forums; they are frequently secondary malware.
3. Avoid downloading cracked software or keygens, which remain the near-exclusive initial access vector for STOP.

References & External Analysis

• Emsisoft Threat Research: STOP/Djvu Ransomware Decryption Guide
• BleepingComputer: STOP Ransomware Technical Overview and Decryption
• Malwarebytes Labs: Threat Spotlight on STOP/Djvu Ransomware
• Search "stop" on VirusTotal (External Analysis)
• Search "stop" on Any.Run (Sandbox Sandbox)
• Search "stop" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Sinresby
• Stimilik
• Insebro
• Wuji
• Powstage
• Mwpm
• Dunco
• Imaut

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/stop.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.