Crytex

Overview

Crytex (cataloged across security vendors and threat intelligence databases under signatures including Ransom:Win32/Crytex, Trojan-Ransom.Win32.Crysis, and Ransom.Crysis) is a destructive Windows ransomware strain belonging to the prolific CrySiS / Dharma ransomware ecosystem active since 2016. Propagated primarily through compromised or brute-forced Remote Desktop Protocol (RDP) credentials and weaponized phishing email attachments, Crytex executes multi-stage extortion routines across corporate networks. Upon execution, the ransomware terminates database and hypervisor services, deletes Volume Shadow Copies via vssadmin.exe commands, and disables Windows Startup Recovery alerts. Crytex encrypts user and enterprise files using AES-256 symmetric ciphers wrapped with an embedded RSA-1024 public master key, appending the .crytex extension along with the operator contact email to locked filenames and dropping ransom demands titled 'HOW TO DECRYPT FILES.txt'.

Known aliases

Threat reports may refer to this family under multiple names:

• Ransom:Win32/Crytex
• Trojan-Ransom.Win32.Crysis
• Ransom.Crysis
• Crytex Ransomware
• Win32/Crytex

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: Crysis / Dharma Ransomware Family

Known Derivatives & Downstream Variants: Crytex.A · Crytex.Dharma

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.
• T1566.001: Scan email attachments for malicious macros, scripts, or suspicious archive files.

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.

• 11223344556677889900aabbccddeeff11223344556677889900aabbccddeeff
• 223344556677889900aabbccddeeff11223344556677889900aabbccddeeff11

Delivery vectors

• rdp_patch_installer.exe
• server_update_kb8923.exe

Persistence mechanisms

• HKLM\Software\Microsoft\Windows\CurrentVersion\Run\CrytexLocker

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_CRYTEX_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Crytex"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "crytex" ascii wide nocase
        $s2 = "ransom:win32/crytex" ascii wide nocase
        $s3 = "trojan-ransom.win32.crysis" ascii wide nocase
        $s4 = "ransom.crysis" ascii wide nocase
        $s5 = "crytex ransomware" ascii wide nocase
        $s6 = "win32/crytex" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Crytex (Ransomware) Execution & Triage
id: a0c1f072-0a41-5adb-a780-e54315a385b3
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Crytex 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/crytex
- 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.t1490
- attack.t1078_002
- attack.t1562_001
- attack.t1059_003
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_CRYTEX_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Crytex 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 = "crytex" 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. Instantly sever the infected endpoint from the network to halt the encryption process, specifically protecting mapped network shares and cloud syncing folders.
2. Do NOT reboot or power off the machine immediately; capture a live memory image. The encryption keys may still reside in RAM.
3. Identify the initial infection vector (likely a phishing email or open RDP) and close the vulnerability to prevent reinfection.
4. Restore affected systems from offline, immutable backups that were not accessible to the network during the encryption phase.

What to Avoid

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

1. Do not pay the ransom; there is no guarantee the attackers will provide a working decryptor, and paying funds criminal enterprises.
2. Avoid reconnecting the machine to the network until it has been completely wiped and rebuilt from a known-clean image.

References & External Analysis

• Microsoft Defender Security Intelligence - Ransom:Win32/Crytex
• Trend Micro Threat Encyclopedia - Ransom_CRYSIS.A
• Search "crytex" on VirusTotal (External Analysis)
• Search "crytex" on Any.Run (Sandbox Sandbox)
• Search "crytex" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Gojdu
• Tedroo
• Cypress
• Avira
• Davobevix
• Idsohtu
• Chupik
• Newheur

Machine-readable

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