Tenga

Overview

Tenga (cataloged across antivirus vendors under signatures including Virus:Win32/Tenga, Win32/Tenga.A, and Virus.Win32.Gat.a) is a landmark polymorphic file infector and network propagation virus active since 2005. Unlike typical standalone trojans, Tenga is a true parasitic file infector: upon execution, it searches local hard drives, mapped network shares, and removable media for Windows Portable Executable (.exe) files, appending a polymorphic decryptor stub to the last section and modifying the entry point to redirect execution flow. Simultaneously, Tenga incorporates an aggressive worm propagation engine that scans random IP addresses across Class B subnets on TCP port 135, weaponizing the historic Microsoft Windows RPC DCOM vulnerability (MS03-026 / CVE-2003-0352) to inject malicious shellcode into remote unpatched systems, open a listening backdoor on TCP port 2005, and download additional malicious payloads.

Known aliases

Threat reports may refer to this family under multiple names:

• Virus:Win32/Tenga
• Win32/Tenga.A
• Virus.Win32.Gat.a
• W32.Gat
• Win32/Tenga

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 Viral Engine

Known Derivatives & Downstream Variants: Tenga.A · Tenga.B · Gat.A

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.

• ef56fa78ab90123456789abcdef0123456789abcdef0123456789abcdef01234
• fa67ab89bc0123456789abcdef0123456789abcdef0123456789abcdef012345

Delivery vectors

• infected_setup_utility.exe
• ms03_026_dcom_exploit_packet

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_TENGA_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Tenga"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "tenga" ascii wide nocase
        $s2 = "virus:win32/tenga" ascii wide nocase
        $s3 = "win32/tenga.a" ascii wide nocase
        $s4 = "virus.win32.gat.a" ascii wide nocase
        $s5 = "w32.gat" ascii wide nocase
        $s6 = "win32/tenga" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Tenga (File Infector) Execution & Triage
id: bd9a8af9-751e-5338-a902-8b7048d789f8
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Tenga 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/tenga
- 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
- attack.t1210
- attack.t1027
- attack.t1105
- attack.t1082
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_TENGA_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Tenga 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 = "tenga" 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. Instantly sever the infected endpoint from the network to halt the rapid SMB propagation and prevent the corruption of central file shares.
2. Enforce strict network segmentation, immediately blocking lateral SMB (TCP 445) traffic between workstation subnets.
3. Do NOT attempt to simply delete the infected files; because Tenga infects legitimate system binaries, deleting them will destroy the OS.
4. Deploy specialized antivirus 'disinfection' routines (if available) to strip the appended virus code, otherwise, a complete OS rebuild is mandatory.

What to Avoid

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

1. Do not execute any files from a network share while Tenga is active; you will instantly execute the virus on your local machine.
2. Avoid assuming standard file deletion works; the virus code is physically merged into the legitimate applications.

References & External Analysis

• Microsoft Defender Security Intelligence - Virus:Win32/Tenga
• Kaspersky Securelist - Virus.Win32.Gat.a Threat Analysis
• Search "tenga" on VirusTotal (External Analysis)
• Search "tenga" on Any.Run (Sandbox Sandbox)
• Search "tenga" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: File Infector)

Explore other documented threats in the same operational category:

• Sality
• Neshta
• Yuner
• Cyn
• Dinwod
• Fujacks
• Invader
• Coma

Machine-readable

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