Lost_Door

Overview

Lost Door (cataloged across security software as Backdoor.LostDoor, Trojan.Win32.LostDoor, and Backdoor:Win32/LostDoor) is a classic Delphi-authored Remote Access Trojan (RAT) created in 2007 by an underground developer known as 'Türkojan' / 'Lost_Door'. Widely adopted across global cybercriminal forums, Lost Door provides full remote administrative control over compromised Windows endpoints. Its capabilities include real-time desktop screen capture, webcam surveillance, audio recording, reverse command shells, registry editing, active process management, and automated password extraction from web browsers, email clients, and instant messengers. Lost Door was commonly distributed through peer-to-peer file sharing networks, malicious email attachments, and trojanized freeware software bundles.

Known aliases

Threat reports may refer to this family under multiple names:

• Backdoor.LostDoor
• Trojan.Win32.LostDoor
• Backdoor:Win32/LostDoor
• Win32/LostDoor.RAT
• LostDoor.E-Server

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: Delphi Rat Frameworks

Known Derivatives & Downstream Variants: Lost Door V6.0 · Lost Door V8.0 · Lost Door Fly Edition

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:

• T1056.001: Implement Endpoint Detection and Response (EDR) to monitor for suspicious API calls related to keystroke interception. Enforce Multi-Factor Authentication (MFA) to render stolen passwords useless.
• 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.
• T1113: Monitor for frequent or unauthorized screen captures or clipboard reads. Restrict background applications from accessing desktop APIs.
• T1125: Restrict access to local camera or microphone APIs. Utilize endpoint protection that monitors hardware access.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Exploited Vulnerabilities (CVEs)

This malware family is documented weaponizing the following common vulnerabilities and exposures:

• CVE-2010-2568 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2012-0158 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).

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.

• 3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f
• 8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b

Delivery vectors

• Peer-to-peer file sharing networks disguised as software cracks and game cheat tools
• Phishing emails with malicious Microsoft Office attachments exploiting CVE-2012-0158

Persistence mechanisms

• HKLM\Software\Microsoft\Windows\CurrentVersion\Run\LostDoorServer
• Startup folder shortcut in %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup

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_LOST_DOOR_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Lost_Door"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "lost_door" ascii wide nocase
        $s2 = "backdoor.lostdoor" ascii wide nocase
        $s3 = "trojan.win32.lostdoor" ascii wide nocase
        $s4 = "backdoor:win32/lostdoor" ascii wide nocase
        $s5 = "win32/lostdoor.rat" ascii wide nocase
        $s6 = "lostdoor.e-server" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Lost_door (Rat) Execution & Triage
id: 4780a5f4-5fbb-58f3-9985-031cfc4ddfc5
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Lost_door malware family. Detects unauthorized persistence creation via
  Windows Registry Run keys, scheduled tasks, and privilege escalation indicative
  of RAT installations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/lost_door
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-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.rat
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1056_001
- attack.t1113
- attack.t1125
- attack.t1123
- attack.t1059_003
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \reg.exe
    - \schtasks.exe
    - \cmd.exe
    - \powershell.exe
    CommandLine|contains:
    - \CurrentVersion\Run
    - /create /tn
    - bypass -enc
    - net user /add
    - net localgroup administrators
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: high

rule MALWARE_WIN_LOST_DOOR_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Lost_Door 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 = "lost_door" 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. Isolate compromised endpoints to cut active remote command sessions and stop live webcam/desktop streaming.
2. Kill active Lost Door server processes and remove autostart entries.
3. Purge persistence registry entries located under HKLM and HKCU Run keys.
4. Perform an enterprise-wide password reset for all user accounts accessed from the infected workstation.

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 downloaded from unverified peer-to-peer file sharing repositories or forum links.
2. Avoid continuing operation of a compromised endpoint without thorough forensic memory triage.

References & External Analysis

• Kaspersky Threat Intelligence - Backdoor.Win32.LostDoor
• Trend Micro Threat Encyclopedia - Backdoor.Win32.LostDoor
• NIST National Vulnerability Database - CVE-2010-2568
• Search "lost_door" on VirusTotal (External Analysis)
• Search "lost_door" on Any.Run (Sandbox Sandbox)
• Search "lost_door" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Rat)

Explore other documented threats in the same operational category:

• Bifrost
• Netwiredrc
• Beast
• Recam
• Xtrat
• Netbus
• Ircbot
• Bandook

Machine-readable

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