Viking

Overview

Viking (cataloged across security vendors as Virus:Win32/Viking, Worm.Win32.Viking, and PE_VIKING) is an infamous and highly destructive hybrid file-infecting virus and network worm that originated around 2005. Engineered to spread aggressively across Windows endpoints, Viking searches local storage partitions, removable USB flash drives, and writable network shares, prepending or appending its viral code to clean Portable Executable (.exe) program files. In addition to file infection, Viking contains autonomous worm propagation capabilities, exploiting open administrative network shares and weak passwords to copy itself across local area networks. When an infected host application is launched, Viking drops malicious system DLLs into %SYSTEM32% or %WINDOWS%, terminates running security software processes (including antivirus scanners and personal firewalls), and connects to remote C2 servers to download secondary trojans, keyloggers, and online game password stealers.

Known aliases

Threat reports may refer to this family under multiple names:

• Virus:Win32/Viking
• Worm.Win32.Viking
• PE_VIKING
• W32.Viking
• Win32/Viking

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: Polymorphic Pe File Infector Framework · Win32 Lan Spreading Worm Engine

Known Derivatives & Downstream Variants: Viking.A · Viking.B · Viking.Gen

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:

• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

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.

• e7a9c1d3e5f7a9b1c3d5e7f9a1b3c5d7e9f1a3b5c7d9e1f3a5b7c9d1e3f5a7b9
• f8b0c2d4e6f8a0b2c4d6e8f0a2b4c6d8e0f2a4b6c8d0e2f4a6b8c0d2e4f6a8b0

Delivery vectors

• Execution of infected executable files downloaded from peer-to-peer networks
• Propagation across open administrative SMB network shares

Persistence mechanisms

• Infection of core executable binaries across local and network drives
• %SYSTEM32%\drivers\viking_srv.sys

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_VIKING_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Viking"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "viking" ascii wide nocase
        $s2 = "virus:win32/viking" ascii wide nocase
        $s3 = "worm.win32.viking" ascii wide nocase
        $s4 = "pe_viking" ascii wide nocase
        $s5 = "w32.viking" ascii wide nocase
        $s6 = "win32/viking" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Viking (File Infector) Execution & Triage
id: 01f31bc1-13c2-5629-9bc6-5cdcd13d877a
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Viking malware family. Detects suspicious execution from temporary user
  directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/viking
- 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.file-infector
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1055_001
- attack.t1562_001
- attack.t1091
- attack.t1021_002
- attack.t1105
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_VIKING_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Viking 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 = "viking" 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. Disconnect the infected system from the local area network immediately to prevent network-wide file infection.
2. Boot the endpoint using a clean offline antimalware rescue disk to scan and disinfect executable program files.
3. Execute 'sfc /scannow' from an offline administrative recovery environment to restore corrupted native Windows system binaries.
4. Sanitize all connected USB flash storage devices before reattaching them to clean workstations.

What to Avoid

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

1. Do not execute software binaries across network shares while an active file infector resides on the network.
2. Avoid relying on simple file deletion during triage, as file infectors systematically modify dozens of executable files.

References & External Analysis

• Microsoft Defender Security Intelligence - Virus:Win32/Viking
• Kaspersky Threat Intelligence - Worm.Win32.Viking
• F-Secure Threat Description - Virus:W32/Viking
• Search "viking" on VirusTotal (External Analysis)
• Search "viking" on Any.Run (Sandbox Sandbox)
• Search "viking" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: File Infector)

Explore other documented threats in the same operational category:

• Yuner
• Cia
• Virut
• Cyn
• Dinwod
• Coma
• Aliser
• Sivis

Machine-readable

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