Jigsaw

Overview

Jigsaw (classified across cybersecurity organizations as Ransom:Win32/Jigsaw, Trojan-Ransom.Win32.Jigsaw, and BitcoinBlackmailer) is a notorious and psychologically manipulative crypto-ransomware family first discovered in March 2016. Developed using the Microsoft .NET framework, Jigsaw is infamous for displaying the iconic face of 'Billy the Puppet' from the 'Saw' horror franchise alongside a ticking countdown clock. Unlike standard ransomware that merely encrypts files and passively awaits payment, Jigsaw employs an active extortion tactic: it systematically deletes an increasing quantity of encrypted files every 60 minutes that ransom payment in Bitcoin is delayed. If the victim terminates the malware process, reboots the computer, or attempts to modify the ransomware binary, Jigsaw punishes the user by deleting 1,000 files immediately upon system restart. Jigsaw encrypts files using AES-128 encryption, appending extensions such as `.fun`, `.gws`, `.kkk`, or `.btc`, and sets up persistent autostart entries under `HKCU\Software\Microsoft\Windows\CurrentVersion\Run` to ensure the deletion countdown resumes upon every boot.

Known aliases

Threat reports may refer to this family under multiple names:

• Ransom:Win32/Jigsaw
• Trojan-Ransom.Win32.Jigsaw
• Win32/Jigsaw
• BitcoinBlackmailer
• Jigsaw Ransomware
• Saw Ransomware

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_JIGSAW_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Jigsaw"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "jigsaw" ascii wide nocase
        $s2 = "ransom:win32/jigsaw" ascii wide nocase
        $s3 = "trojan-ransom.win32.jigsaw" ascii wide nocase
        $s4 = "win32/jigsaw" ascii wide nocase
        $s5 = "bitcoinblackmailer" ascii wide nocase
        $s6 = "jigsaw ransomware" ascii wide nocase
        $s7 = "saw ransomware" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Jigsaw (Ransomware) Execution & Triage
id: e74016e4-5040-5953-bbf4-24a27ac61b9e
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Jigsaw 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/jigsaw
- 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.t1485
- attack.t1491
- 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_JIGSAW_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Jigsaw 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 = "jigsaw" 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, restart, or attempt to terminate the ransomware process using Task Manager. This will trigger the punitive deletion of 1,000 files.
2. Use a specialized tool (like Process Explorer run from a USB drive) to specifically suspend the active Jigsaw threads in memory before attempting termination.
3. Once the process is safely suspended/terminated, locate and remove the autostart entries in the Registry and Startup folder.
4. Do NOT pay the ransom. Decryption tools for older Jigsaw variants are freely available from projects like 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 abruptly restart the computer; this is exactly what the malware is waiting for to delete bulk data.
2. Avoid paying the ransom; due to flaws in Jigsaw's early implementations, the decryption keys are often hardcoded or extractable from memory.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Ransom:Win32/Jigsaw
• Trend Micro Security Intelligence - Jigsaw Ransomware Technical Breakdown
• MITRE ATT&CK - Data Destruction (T1485)
• Search "jigsaw" on VirusTotal (External Analysis)
• Search "jigsaw" on Any.Run (Sandbox Sandbox)
• Search "jigsaw" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Saturn
• Sixmuch
• Msildrop
• Activator
• Figyek
• Covus
• Minebicoin
• Weiduan

Machine-readable

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