Gandcrypt

Overview

Ransom:Win32/GandCrypt (widely cataloged across endpoint telemetry as Trojan-Ransom.Win32.GandCrypt, Ransom.GandCrab, or Win32/GandCrypt) is the Microsoft Defender detection label for the notorious GandCrab ransomware cartel and its primary encryption binaries. Operating as one of the cybercrime underground's first industrial-scale Ransomware-as-a-Service (RaaS) operations between 2018 and 2019, GandCrab/GandCrypt infected hundreds of thousands of corporate and municipal networks globally. Distributed through exploit kits (Fallout, GrandSoft), malspam campaigns with weaponized attachments, and compromised RDP credentials, GandCrypt enumerates local storage, mounted network volumes, and SMB shares. It terminates database and enterprise processes (SQL, Exchange), deletes Volume Shadow Copies via vssadmin and wmic, and encrypts victim files using strong AES-256 and RSA-2048 cryptography, appending extensions such as .gdcb, .crab, or .krab while demanding ransom payments in DASH and Bitcoin.

Known aliases

Threat reports may refer to this family under multiple names:

• GandCrypt
• Ransom:Win32/GandCrypt
• Trojan-Ransom.Win32.GandCrypt
• Ransom.GandCrab
• Win32/GandCrypt
• GandCrab Encryptor
• Ransom:Win32/GandCrypt.DB!MTB

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: Gandcrab Ransomware-As-A-Service Lineage

Known Derivatives & Downstream Variants: Ransom:Win32/Gandcrypt.A · Ransom:Win32/Gandcrypt.Db!Mtb · Trojan-Ransom.Win32.Gandcrypt.Gen

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:

• 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):

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.

• e5f6a7b8c9d01a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b
• b5a403129876543210abcdef0123456789abcdef0123456789abcdef01234567

Delivery vectors

• Exploit kits (Fallout, GrandSoft) on compromised sites
• Malspam campaigns with weaponized attachments (.doc, .zip)
• Brute-forced Remote Desktop Protocol (RDP) credentials

Persistence mechanisms

• HKLM\Software\Microsoft\Windows\CurrentVersion\Run\GandCryptLocker
• GDCB-DECRYPT.txt ransom note in infected directories

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_GANDCRYPT_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Gandcrypt"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "gandcrypt" ascii wide nocase
        $s2 = "gandcrypt" ascii wide nocase
        $s3 = "ransom:win32/gandcrypt" ascii wide nocase
        $s4 = "trojan-ransom.win32.gandcrypt" ascii wide nocase
        $s5 = "ransom.gandcrab" ascii wide nocase
        $s6 = "win32/gandcrypt" ascii wide nocase
        $s7 = "gandcrab encryptor" ascii wide nocase
        $s8 = "ransom:win32/gandcrypt.db!mtb" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Gandcrypt (Ransomware) Execution & Triage
id: 7f683660-b4cf-5a44-a96b-f30c2bcac2aa
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Gandcrypt 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/gandcrypt
- 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.t1489
- attack.t1490
- attack.t1059_003
- 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_GANDCRYPT_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Gandcrypt 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 = "gandcrypt" 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. Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Gandcrypt from spreading laterally or encrypting network-attached storage (NAS) and shared SMB volumes.
2. Preserve volatile system memory (RAM capture) on a representative endpoint before attempting a reboot or power-down, as Gandcrypt symmetric encryption keys or uncompiled payload components may still reside in memory.
3. Audit process execution logs and terminate active scripting interpreters (e.g. PowerShell, CMD, WScript) or commands executing 'vssadmin.exe delete shadows' or 'wbadmin' used by Gandcrypt to inhibit recovery.
4. Investigate the initial compromise vector (such as exposed RDP instances, spearphishing attachments, or vulnerable edge gateways) and enforce an immediate credential reset for all compromised Active Directory accounts.
5. Restore critical assets and databases exclusively from verified, air-gapped, or immutable offline backups once the Gandcrypt binary and related persistence hooks are eradicated.

What to Avoid

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

1. Do not restart or power cycle infected systems prematurely; doing so destroys volatile RAM encryption keys and may trigger bootloader locking logic embedded in Gandcrypt.
2. Avoid negotiating or paying the extortion demand without prior forensic evaluation and consultation with incident response specialists, as payment does not guarantee data recovery.
3. Do not connect clean backup drives or external storage to the affected network until Gandcrypt eradication is completely verified.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Ransom:Win32/GandCrypt
• Trend Micro Threat Encyclopedia - Ransom.GandCrab
• Europol & NoMoreRansom - GandCrab Decryptor Release
• Search "gandcrypt" on VirusTotal (External Analysis)
• Search "gandcrypt" on Any.Run (Sandbox Sandbox)
• Search "gandcrypt" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Itva
• Quervar
• Qqfarmer
• Defsel
• Redeye
• Swog
• Taskkill
• Ocna

Machine-readable

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