Cryfile

Overview

Ransom:Win32/Cryfile is a severe threat classified as Ransomware. It is designed to extort victims by strongly encrypting critical personal or corporate data, appending a specific extension to the files, and demanding payment in cryptocurrency for the decryption key.

Understanding Cryfile
To an end-user, a Cryfile infection represents an immediate crisis: documents and databases are suddenly inaccessible, and a ransom note (often a `.txt` or `.hta` file) is presented on the desktop. For an enterprise, it triggers a 'Code Red' incident response, requiring immediate network isolation to prevent lateral movement and the encryption of enterprise file shares and backups.

Execution and Extortion Mechanics
Cryfile is frequently distributed via targeted phishing (`T1566.001`), exploit kits, or dropped by other initial access malware. Upon execution, it achieves persistence (`T1547.001`) and actively attempts to impair endpoint defenses (`T1562.001`). Crucially, before encryption begins, it executes commands like `vssadmin.exe delete shadows /all /quiet` to destroy Windows Volume Shadow Copies, preventing easy system restoration (`T1490`). It then rapidly iterates through the filesystem and mapped network drives, encrypting files matching high-value extensions (e.g., `.docx`, `.sql`, `.pdf`) using robust encryption algorithms (`T1486`).

Indicators of Compromise & Impact
The impact is catastrophic data loss. Host-based IoCs include massive spikes in disk I/O and CPU usage during the encryption phase, the sudden appearance of ransom note files in every directory, and EDR alerts for `vssadmin.exe` or `wmic.exe` attempting to delete shadow copies. Network IoCs may include anomalous outbound traffic if the ransomware incorporates a data exfiltration module.

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:

• 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):

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_CRYFILE_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Cryfile"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "cryfile" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Cryfile (Ransomware) Execution & Triage
id: 43f8e8ba-b925-5966-bc5e-cf4f30b09d43
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Cryfile 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/cryfile
- 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.t1566_001
- attack.t1562_001
- 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: critical

rule MALWARE_WIN_CRYFILE_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Cryfile 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 = "cryfile" 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 physically disconnect the infected endpoint from the network (pull the Ethernet cable) to stop the ransomware from encrypting network shares and spreading laterally.
2. Do NOT reboot the infected machine; if possible, capture a live memory image (RAM dump) as the encryption keys might temporarily reside in memory.
3. Restore the encrypted systems from secure, offline backups that were isolated from the network at the time of the attack.
4. Verify the integrity of Active Directory; ransomware is often deployed network-wide by attackers who have already compromised Domain Admin credentials.

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 immediately; paying funds criminal syndicates, and there is no guarantee the provided decryptor will actually work.
2. Avoid reconnecting restored machines to the network until the initial entry vector has been completely secured.

References & External Analysis

• Search "cryfile" on VirusTotal (External Analysis)
• Search "cryfile" on Any.Run (Sandbox Sandbox)
• Search "cryfile" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Nscauth
• Hqsi
• Jbomi
• Donex
• Ammyy
• Ukpa
• Snoload
• Idlekms

Machine-readable

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