Ranserkd

Overview

Ransom:Win32/Ranserkd is a highly destructive ransomware variant designed to systematically encrypt all valuable data on an infected endpoint or network share, followed by an extortion demand. It utilizes strong cryptographic algorithms (typically AES combined with RSA) to ensure that recovering the locked files is mathematically impossible without paying the attackers for the unique private decryption key.

Understanding the Ranserkd Threat
To a victim, a Ranserkd infection represents a catastrophic loss of data; documents, databases, and photos become inaccessible, appended with a strange file extension, and a ransom note appears on the desktop. For an enterprise, it triggers a critical incident response involving total network isolation to prevent the ransomware from spreading to critical servers and backups.

Execution and Encryption Mechanics
Ranserkd is frequently deployed manually by attackers after they have already breached the network (e.g., via compromised RDP credentials or an Initial Access Broker) (`T1078`), or delivered via massive malspam campaigns (`T1566.001`). Upon execution, the ransomware first attempts to neutralize endpoint defenses and delete Windows Volume Shadow Copies (`vssadmin.exe delete shadows`) to prevent easy data restoration (`T1490`). It then aggressively scans all local drives and mapped network shares, rapidly encrypting files that match a hardcoded list of valuable extensions (e.g., `.docx`, `.sql`, `.pdf`) (`T1486`). Finally, it drops a ransom note (often a `.txt` or `.html` file) detailing payment instructions via cryptocurrency.

Indicators of Compromise & Impact
The impact is total data denial of service. Host-based IoCs include massive spikes in CPU and disk I/O activity caused by the rapid encryption process. EDR systems will flag the execution of `vssadmin.exe` or `bcdedit.exe` attempting to disable recovery features. Files across the system will suddenly change extensions, and the ransomware executable itself may be found running from the `%Temp%` or `%AppData%` directories.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

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

Sigma Rule

title: Suspicious Ranserkd Activity
id: 22660d0e564fa3659e58ec1d7b3517dc
status: experimental
description: Detects generic indicators of the ranserkd malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*ranserkd*"
    condition: selection
level: medium

Containment & Response Steps

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

1. Immediately sever the infected endpoint from the network (physically pull the Ethernet cable or disable the switch port) to stop it from encrypting mapped network drives.
2. Do NOT reboot the infected machine; capture a live memory image (RAM dump), as the encryption keys might temporarily reside in memory.
3. Identify the exact Ranserkd variant and consult resources like 'No More Ransom' to see if a known decryption flaw exists before considering payment.
4. Restore the encrypted systems from secure, offline backups that were isolated from the network at the time of the attack.

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 (e.g., a vulnerable VPN or weak RDP password) has been completely secured.

References & External Analysis

• Search "ranserkd" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Gpukj
• Code
• Meinhudong
• Hptrickbot
• Donloz

Machine-readable

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