Garrun

Overview

Garrun (identified in security research telemetry as Trojan:Win32/Garrun, Trojan:Win32/Garrun.A, and Backdoor:Win32/Garrun) is an evasive Windows trojan backdoor and command execution implant. Infiltrating target endpoints via weaponized spearphishing email attachments and secondary exploit droppers, Garrun deploys a multi-stage execution chain that verifies whether it is operating within an isolated analysis sandbox. Once safe execution is confirmed, Garrun establishes autostart persistence by configuring Windows Task Scheduler tasks and modifying startup registry keys. It opens an encrypted command-and-control connection to remote infrastructure, giving attackers interactive command shell execution, arbitrary file upload and download capabilities, and the ability to stage auxiliary payload components.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Garrun
• Trojan:Win32/Garrun.A
• Backdoor:Win32/Garrun
• Win32/Garrun
• Backdoor.Garrun

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):

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_GARRUN_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Garrun"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "garrun" ascii wide nocase
        $s2 = "trojan:win32/garrun" ascii wide nocase
        $s3 = "trojan:win32/garrun.a" ascii wide nocase
        $s4 = "backdoor:win32/garrun" ascii wide nocase
        $s5 = "win32/garrun" ascii wide nocase
        $s6 = "backdoor.garrun" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Garrun (Trojan) Execution & Triage
id: b5d38c69-1ae1-5845-9cc2-0624318ac4ac
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Garrun 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/garrun
- 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.t1053_005
- attack.t1547_001
- attack.t1071_001
- 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_GARRUN_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Garrun 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 = "garrun" 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. Sever the affected system's network connections immediately to prevent attacker command execution.
2. Terminate active backdoor processes and inspect %APPDATA% and %TEMP% for staged binaries.
3. Remove scheduled tasks configured by Garrun using schtasks.exe.
4. Clean registry run values under HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
5. Block identified C2 IP addresses and domain names at perimeter firewalls and DNS resolvers.

What to Avoid

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

1. Do not allow the infected host to maintain internet connectivity during analysis.
2. Do not ignore secondary payloads that may have been downloaded via Ingress Tool Transfer routines.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Trojan:Win32/Garrun
• Trend Micro Threat Encyclopedia - Backdoor.Win32.Garrun
• VirusTotal Threat Intelligence - Garrun Sample Telemetry
• Search "garrun" on VirusTotal (External Analysis)
• Search "garrun" on Any.Run (Sandbox Sandbox)
• Search "garrun" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Corebot
• Occamy
• Socks
• Findkeyxp
• Addlyrics
• Aauto
• Picsys
• Taranis

Machine-readable

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