Trojna

Overview

Trojna (cataloged across early antivirus archives as TrojNa$, Trojan.Trojna, and Backdoor.Win32.Trojna) is an early-2000s Remote Access Trojan created in Visual Basic and Delphi. Developed during the golden era of classic Windows backdoors, Trojna was designed to afford remote unauthorized operators comprehensive control over compromised Windows 9x, ME, and 2000 endpoints. Upon initial infection, Trojna copies its server binary into system folders, creates autostart registry entries under the Windows Run keys, and opens a persistent listening TCP socket to await commands from an attacker client console. The trojan features a wide range of remote administration capabilities, including file system browsing, file upload and download, remote process enumeration and termination, registry hive manipulation, system rebooting, desktop screen captures, and keystroke logging.

Known aliases

Threat reports may refer to this family under multiple names:

• TrojNa$
• Backdoor.Trojna
• Trojan.Win32.Trojna
• TrojNa 1.0
• Backdoor:Win32/Trojna

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: Vintage Win32 Backdoor Frameworks

Known Derivatives & Downstream Variants: Trojna 1.0 · Trojna 1.1 · Trojna.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:

• T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• 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.

• a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1
• 4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5f

Delivery vectors

• Distribution across vintage IRC file sharing channels and P2P networks
• Deceptive email attachments masquerading as software tools or games

Persistence mechanisms

• HKLM\Software\Microsoft\Windows\CurrentVersion\Run\TrojnaServer
• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\TrojnaSys

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_TROJNA_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Trojna"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "trojna" ascii wide nocase
        $s2 = "trojna$" ascii wide nocase
        $s3 = "backdoor.trojna" ascii wide nocase
        $s4 = "trojan.win32.trojna" ascii wide nocase
        $s5 = "trojna 1.0" ascii wide nocase
        $s6 = "backdoor:win32/trojna" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Trojna (Trojan) Execution & Triage
id: 40f7b786-d827-5c9c-88de-aca668151e7d
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Trojna 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/trojna
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-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.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1059_003
- attack.t1547_001
- attack.t1083
- attack.t1105
- attack.t1071_001
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_TROJNA_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Trojna 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 = "trojna" 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 affected computer from the local network to terminate active attacker sessions.
2. Kill the Trojna server process using Task Manager or administrative command prompts.
3. Remove startup keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
4. Delete the server binary from the Windows System32 directory.

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 attachments received from unknown sources or IRC chat networks.
2. Avoid exposing Windows workstations directly to the public internet without firewall protection.

References & External Analysis

• Broadcom Symantec Security Response - Backdoor.Trojna
• Malware Museum Historical Backdoor Archive - Trojna
• Search "trojna" on VirusTotal (External Analysis)
• Search "trojna" on Any.Run (Sandbox Sandbox)
• Search "trojna" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Spamer
• Xiaobaminer
• Browshot
• Vanbot
• Bmkfxasqf6Ki
• Gampass
• Securityshield
• Bobax

Machine-readable

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