Cryptomix
Table of Contents
Overview
Ransomware:Win32/Cryptomix is a well-known, historically significant ransomware family. Its primary objective is to encrypt the victim's files using strong cryptographic algorithms (typically RSA-2048 and AES-256) (`T1486`) and extort cryptocurrency. Cryptomix is notable for its numerous variants (like Cryptoshield), its shifting network of payment portals hosted on the Tor network, and its aggressive deletion of system recovery options.
Understanding Cryptomix (Ransomware)
To an end-user, a Cryptomix infection is devastating. They will suddenly find their documents, photos, and databases inaccessible, appended with an extension (which varied heavily between versions, e.g., `.scl`, `.code`, `.rmp`), accompanied by a stark 'Ransom Note' providing instructions to pay the attackers via Bitcoin. For an organization, it represents a critical incident requiring immediate network isolation.
Execution and Encryption Mechanics
Cryptomix was typically delivered via exploit kits (like RIG or GrandSoft) or via malicious spam attachments. Upon execution, it immediately executes commands to delete Volume Shadow Copies (`vssadmin.exe delete shadows`) (`T1490`) and disable the Windows Startup Repair feature to prevent easy data recovery. It then rapidly traverses local drives and mapped network shares (`T1012`), encrypting files. A unique feature of early Cryptomix was its reliance on a hardcoded list of public keys; if it couldn't reach its C2 server, it would use an 'offline' key, which security researchers were sometimes able to extract to build free decryptors.
Indicators of Compromise & Impact
The impact is the total loss of data availability. Host-based IoCs include the sudden renaming of thousands of files, the presence of ransom notes (e.g., `HELP_INSTRUCTION.txt`), and EDR alerts for rapid file modification operations. System logs will show the execution of commands designed to inhibit system recovery (`vssadmin`, `bcdedit`). Network IoCs include DNS requests to known Cryptomix C2 infrastructure, often routing through compromised websites.
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):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-RQA | Registry Query Auditing | Detect | T1012 | Audit mass registry queries targeted at security posture, installed software, and system configuration hives. |
D3-FAED | File Alteration Early Detection | Detect | T1486 | Deploy canary files and monitor mass rename/encryption I/O spikes to terminate ransomware threads immediately. |
D3-VSS | Volume Shadow & Snapshot Hardening | Harden | T1490 | Block execution of vssadmin.exe and wmic shadowcopy delete; maintain air-gapped immutable backup repositories. |
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:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_CRYPTOMIX_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Cryptomix"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "cryptomix" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Cryptomix (Ransomware) Execution & Triage
id: b58cfd4b-8e17-5c09-9a71-56bdd01a8893
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Cryptomix 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/cryptomix
- 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.t1012
- attack.t1490
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: criticalTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_CRYPTOMIX_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Cryptomix 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 = "cryptomix" 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.
- Isolate the infected machine from the network immediately to stop the encryption process from spreading to mapped network shares.
- Do not reboot the machine; if the encryption process is active, rebooting may finalize the damage or destroy volatile memory keys.
- Check resources like 'No More Ransom' to see if a free decryptor exists for the specific variant of Cryptomix you are facing.
- Restore operations from known-good, offline backups; paying the ransom is highly discouraged and funds criminal enterprises.
What to Avoid
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
- Do not connect backup drives to the infected machine until it has been completely wiped and reimaged.
- Avoid paying the ransom unless absolutely critical for human safety, as Cryptomix operators were known for poor customer service and failing to deliver decryptors.
References & External Analysis
- Search "cryptomix" on VirusTotal (External Analysis)
- Search "cryptomix" on Any.Run (Sandbox Sandbox)
- Search "cryptomix" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Cryptomix and what threat category does it belong to?
Cryptomix is classified as a Ransomware. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Cryptomix establish persistence and evade defensive controls?
Cryptomix typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Cryptomix compromise?
Security teams responding to Cryptomix should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What cryptographic algorithms and file targeting techniques does Cryptomix employ during execution?
Cryptomix typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options.
Are decryptors available for Cryptomix, and what is the recommended recovery procedure?
Decryption availability for Cryptomix depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups.
How do I remove Cryptomix from Windows?
Manual removal of Cryptomix is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
What are the main symptoms of a Cryptomix infection?
Symptoms of Cryptomix can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Protect Your Network Against Ransomwares
Want to prevent Cryptomix and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Containment & Incident Response.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
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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.