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 the MITRE ATT&CK framework:

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_JIGSAWLOCKER {
    meta:
        description = "Detects Jigsawlocker (ransomware)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "jigsawlocker" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Jigsawlocker Activity
id: a9dff13d3af7bc3e3cba317c87c924e2
status: experimental
description: Detects generic indicators of the jigsawlocker malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*jigsawlocker*"
    condition: selection
level: medium

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)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Comisproc
• Flvdirect
• Muma
• Kabymj
• Necne

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/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.