Zegost

Overview

Trojan:Win32/Zegost (widely documented by threat researchers as Backdoor.Zegost or Zegost RAT) is a sophisticated cyber espionage Remote Access Trojan and rootkit platform developed and utilized by East Asian Advanced Persistent Threat (APT) groups in targeted campaigns against defense contractors, government ministries, and technology corporations. Engineered for long-term clandestine surveillance, Zegost deploys kernel-mode rootkit drivers to hide its processes, files, and network sockets from endpoint detection and response (EDR) platforms. Operating with an exhaustive espionage feature set, Zegost records keystrokes, captures screenshots, dumps credentials directly from LSASS process memory, executes interactive command shells, and exfiltrates sensitive intellectual property using heavily encrypted custom C2 protocols disguised as standard web traffic.

Known aliases

Threat reports may refer to this family under multiple names:

• Zegost
• Trojan:Win32/Zegost
• Backdoor.Zegost
• Trojan.Zegost
• Zegost RAT
• Win32/Zegost
• Backdoor:Win32/Zegost

Threat Actor Attribution

Attribution is probabilistic, not a science. Each link below states its confidence level and the evidence behind it.

• East Asian State-Sponsored APT Groups High confidence
  Basis:

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Known Derivatives & Downstream Variants: Zegost V1.X · Zegost Rootkit Build · Zegost Custom C2 Variant

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:

• T1003.001: Monitor for LSASS memory dumping or registry SAM extraction. Enable Credential Guard on Windows systems.
• 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.

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-2012-0158 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2014-4114 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).

Command & Control (C2) and Network Profile

How this family talks to its operators. C2 traffic can often identify a family even when its code and configuration are hard to analyse. Ports and patterns are historical and change between campaigns, so use them as hunting leads rather than block-only rules.

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.

• 4e5f6a7b8091a2b3c4d5e6f708192a3b4c5d6e7f8091a2b3c4d5e6f708192a3b
• 1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d

Delivery vectors

• targeted_spearphishing_attachments
• weaponized_office_documents

Persistence mechanisms

• Windows Service Registration
• HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

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_ZEGOST_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Zegost"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "zegost" ascii wide nocase
        $s2 = "zegost" ascii wide nocase
        $s3 = "trojan:win32/zegost" ascii wide nocase
        $s4 = "backdoor.zegost" ascii wide nocase
        $s5 = "trojan.zegost" ascii wide nocase
        $s6 = "zegost rat" ascii wide nocase
        $s7 = "win32/zegost" ascii wide nocase
        $s8 = "backdoor:win32/zegost" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Zegost (Rat) Execution & Triage
id: 50bc467a-476f-509e-82e8-712d6d614402
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Zegost 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/zegost
- 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.t1014
- attack.t1056_001
- attack.t1003_001
- attack.t1113
- 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_ZEGOST_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Zegost 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 = "zegost" 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 workstations immediately and assume nation-state level persistence.
2. Do not immediately reboot suspect systems; capture live memory to preserve rootkit hook evidence.
3. Engage specialized Incident Response firm with advanced persistent threat triage experience.
4. Deploy security updates patching Microsoft Office and OLE vulnerabilities CVE-2012-0158 and CVE-2014-4114.

What to Avoid

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

1. Do not attempt simple file-based deletion, as Zegost kernel rootkit drivers will resist uninstallation.
2. Avoid communicating incident response details over the compromised enterprise network.
3. Never open unsolicited spear-phishing correspondence received from external defense contractors.

References & External Analysis

• Trend Micro Security Intelligence: Backdoor.Zegost Analysis
• Kaspersky Lab Securelist: Targeted Espionage Backdoors in East Asia
• NIST National Vulnerability Database CVE-2014-4114
• Search "zegost" on VirusTotal (External Analysis)
• Search "zegost" on Any.Run (Sandbox Sandbox)
• Search "zegost" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Rat)

Explore other documented threats in the same operational category:

• Turkojan
• Pcclient
• Nanobot
• Lost_Door
• Farfli
• Apocalypse_Rat
• Nanocore
• Xtrat

Machine-readable

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