Jigsawlocker

Overview

Ransom:Win32/Jigsawlocker (commonly known as Jigsaw) is an exceptionally cruel and psychologically manipulative crypto-ransomware family. Unlike standard ransomware that simply encrypts files and waits for payment, Jigsaw employs a sadistic countdown timer, threatening to permanently delete a batch of files every hour until the ransom is paid, often using imagery of the 'Billy the Puppet' character from the *Saw* horror film franchise to induce panic.

Understanding Jigsaw (Extortion/Time-Bomb Ransomware)
To an end-user, Jigsaw is terrifying. Upon execution, it displays a full-screen, unclosable window with a countdown timer, explicitly stating that if the computer is rebooted or if the user attempts to remove the malware, a massive penalty (e.g., the immediate deletion of 1,000 files) will be enforced. For an incident responder, Jigsaw requires a highly delicate approach; standard remediation tactics (like a hard reboot) will actually trigger the malware's destructive mechanisms.

Execution and Extortion Mechanics
Jigsaw is typically distributed via spam emails or adware bundles (`T1566.001`). Upon execution, it encrypts user files (often using AES) and appends extensions like `.fun`, `.btc`, or `.jigsaw` (`T1486`). It establishes persistence via the `HKCU\Software\Microsoft\Windows\CurrentVersion\Run` registry key (`T1547.001`). The defining characteristic is its extortion mechanism (`T1485` - Data Destruction). The malware monitors system uptime and its own process state. It deletes one file after the first hour, and exponentially increases the number of deleted files every subsequent hour. If the user terminates the Jigsaw process (e.g., via Task Manager) or reboots the machine, the malware detects this upon restart and punishes the user by deleting a large swath of files immediately.

Indicators of Compromise & Impact
The impact is severe data loss and intense psychological pressure. Host-based IoCs include files renamed with Jigsaw-specific extensions, the presence of the full-screen 'Saw' ransom note, and the active deletion of files in user directories. EDR alerts will show a specific executable (often named `drpbx.exe` or `firefox.exe` to blend in) rapidly performing file deletion APIs.

MITRE ATT&CK Techniques

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

MITRE D3FEND™ Defensive Countermeasures

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

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_JIGSAWLOCKER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Jigsawlocker"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "jigsawlocker" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Jigsawlocker (Ransomware) Execution & Triage
id: 59b76ac5-4b9d-5fff-8933-2078a5226557
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Jigsawlocker 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/jigsawlocker
- 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.t1491_001
- attack.t1485
- attack.t1547_001
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_JIGSAWLOCKER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Jigsawlocker 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 = "jigsawlocker" 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. CRITICAL: Do NOT turn off or reboot the infected machine, and do NOT attempt to kill the Jigsaw process via Task Manager, as this triggers the punitive file deletion routine.
2. Immediately physically disconnect the machine from the network (pull the Ethernet cable).
3. In a controlled environment, use specialized anti-ransomware tools to freeze the Jigsaw process in memory (suspending the thread) before attempting removal.
4. Fortunately, older versions of Jigsaw contain cryptographic flaws, and free decryption tools are widely available from security vendors (e.g., No More Ransom).

What to Avoid

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

1. Do not panic and pay the ransom; free decryptors exist for many Jigsaw variants.
2. Absolutely avoid rebooting the computer or forcefully terminating the malware process until the files have been backed up or a decryptor is ready.

References & External Analysis

• Search "jigsawlocker" on VirusTotal (External Analysis)
• Search "jigsawlocker" on Any.Run (Sandbox Sandbox)
• Search "jigsawlocker" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Kz4Aamkfbloj
• Tenavt
• Soulclose
• Stop
• Esendi
• Magni
• Devilz
• Jyuqet

Machine-readable

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