Bitman

Overview

Ransom:Win32/Bitman is a heuristic detection name frequently used by Microsoft Defender and other vendors to classify the highly destructive **TeslaCrypt** ransomware family (and its variants). Bitman emerged prominently around 2015, gaining notoriety for initially targeting PC gamers by encrypting save games and platform configurations, before evolving to target enterprise databases and standard documents for extortion.

Understanding Bitman (TeslaCrypt)
To a victim, a Bitman infection is devastating; they lose access to their personal files, business documents, and uniquely, their video game progress, followed by a demand to pay a ransom in Bitcoin. For incident responders, Bitman represents a classic, fast-moving ransomware threat. Notably, early versions of Bitman contained cryptographic flaws that allowed researchers to build free decryption tools, though later versions fixed these errors.

Execution and Encryption Mechanics
Bitman is most commonly distributed via the Angler Exploit Kit (`T1189`), weaponized spam attachments (`T1566.001`), or malicious links. Upon execution (`T1204.002`), it drops itself into the `%AppData%` directory and establishes persistence via Registry Run keys (`T1547.001`). It immediately scans local and mapped network drives (`T1083`) for over 180 specific file extensions—including standard Office documents, but also specifically targeting files associated with popular games (e.g., `.sav`, `.w3x`, `.minecraft`). It encrypts these files using AES encryption (`T1486`) and alters the file extensions (e.g., to `.ecc`, `.ezz`, `.exx`, or `.vvv`). Finally, it deletes the Volume Shadow Copies (`T1490`) to prevent easy restoration and displays a ransom note styled similarly to CryptoLocker.

Indicators of Compromise & Impact
The impact is massive data loss and potential operational paralysis. The primary IoCs are the sudden renaming of thousands of files to include the specific Bitman/TeslaCrypt extensions and the appearance of ransom notes (`HELP_RESTORE_FILES.txt`). EDR logs will flag the execution of `vssadmin.exe delete shadows /all /quiet`. Network traffic may show the malware communicating with a C2 server (often over Tor) to transmit the encryption keys.

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

Sigma Rule

title: Suspicious Bitman Activity
id: 04e6f130d5d4c1c2ea879c9be5bd3946
status: experimental
description: Detects generic indicators of the bitman malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*bitman*"
    condition: selection
level: medium

Containment & Response Steps

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

1. Instantly isolate the infected endpoint from the network to halt the encryption process, specifically protecting mapped network shares.
2. Determine the exact variant of Bitman/TeslaCrypt based on the appended file extension (e.g., `.vvv`, `.ecc`).
3. Check public resources (like NoMoreRansom) to see if a free decryption tool is available for the specific variant, as the master keys for TeslaCrypt were eventually released by the developers.
4. If no decryptor is available, restore the affected systems from secure, offline backups.

What to Avoid

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

1. Do not reboot the machine immediately; capture a live memory dump (RAM) first, as older variants sometimes left the decryption keys in memory.
2. Avoid paying the ransom, especially for Bitman/TeslaCrypt, as the operators have historically shut down their infrastructure, and free decryptors exist for many versions.

References & External Analysis

• Search "bitman" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Perkiler
• Murka
• Hangup
• Kraddare
• Zurgop

Machine-readable

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