Crypmod

Overview

Ransomware:Win32/Crypmod is a highly destructive malware family that acts as a hybrid between traditional ransomware and a data wiper. Unlike standard ransomware that encrypts files and leaves them recoverable if a key is provided, some variants of Crypmod have been observed intentionally corrupting files or failing to store the decryption keys properly, acting effectively as a destructive wiper.

Understanding Crypmod
To the victim organization, a Crypmod infection is a catastrophic event. Critical servers and workstations are rapidly rendered unusable, with files modified and a ransom note displayed on the desktop or dropped in directories. For incident responders, Crypmod represents a severe failure in perimeter or endpoint security, often arriving via malicious email attachments or exploit kits. The critical issue with Crypmod is that paying the ransom is often futile, as the malware's implementation of cryptography is either flawed or intentionally destructive.

Execution and Destruction Mechanics
Crypmod is typically distributed via spearphishing (`T1566.001`) or as a secondary payload dropped by a botnet. Upon execution, it disables local security software (`T1562.001`) and rapidly enumerates all attached local and network drives (`T1083`). It uses `vssadmin.exe` or WMI to silently delete volume shadow copies (`T1490`), preventing easy rollback. It then begins encrypting (or corrupting) files matching specific extensions (documents, databases, archives) (`T1486`). Persistence is achieved via Registry Run keys to ensure encryption continues if the machine is rebooted.

Indicators of Compromise & Impact
The impact is total operational halt and massive data loss. EDR platforms must alert on the rapid execution of `vssadmin` or `bcdedit` commands designed to inhibit system recovery. The definitive IoC is the presence of encrypted files with unusual extensions (often randomized per variant) and the accompanying ransom note. Network logs may show a brief beacon to a C2 server to register the infection, though some wiper variants operate entirely offline.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the 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.

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

Sigma Rule

title: Suspicious Crypmod Activity
id: 568135e135b2f821c1dc15187964b71c
status: experimental
description: Detects generic indicators of the crypmod malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*crypmod*"
    condition: selection
level: medium

Containment & Response Steps

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

1. Instantly sever the infected endpoint or server from the network by pulling the physical cable to prevent the encryption of mapped network shares.
2. Do not reboot the server if it is actively encrypting; rebooting can destroy cryptographic material in RAM or trigger further destructive routines.
3. Isolate the machine and capture a forensic memory image (RAM dump), as the decryption keys might briefly exist in memory.
4. Begin the incident response process to restore the data from secure, offline, and immutable backups.

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. With Crypmod, paying is exceptionally risky as variants are known to be destructive wipers masquerading as ransomware.
2. Avoid attaching any external backup drives to the infected machine until it has been completely wiped and rebuilt.

References & External Analysis

• Search "crypmod" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Darkmoon
• Mazben
• Bsymem
• Suloc
• Rukoma

Machine-readable

Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/crypmod.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.