Sixxpack

Overview

Sixxpack (classified across endpoint detection telemetry under designations including Trojan:Win32/Sixxpack, Trojan:Win32/Sixxpack.A, and VirTool:Win32/Sixxpack) is an obfuscated multi-stage Windows trojan loader and crypter framework. Designed to evade behavioral monitoring and signature-based antivirus solutions, Sixxpack is distributed via weaponized email attachments, software cracking archives, and malicious download aggregators. Upon initial execution, Sixxpack executes anti-sandbox and debugger evasion routines, resolving API calls dynamically via memory hashes (API hashing) to defeat static analysis. It establishes autostart persistence by configuring Run registry keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run. Sixxpack decrypts an embedded payload in memory and injects the malicious code into legitimate Windows system processes (such as svchost.exe or explorer.exe) using process hollowing or reflective DLL loading, establishing an encrypted C2 channel to execute secondary commands.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Sixxpack
• Trojan:Win32/Sixxpack.A
• VirTool:Win32/Sixxpack
• Win32/Sixxpack
• Trojan.Sixxpack

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:

• 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_SIXXPACK_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Sixxpack"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "sixxpack" ascii wide nocase
        $s2 = "trojan:win32/sixxpack" ascii wide nocase
        $s3 = "trojan:win32/sixxpack.a" ascii wide nocase
        $s4 = "virtool:win32/sixxpack" ascii wide nocase
        $s5 = "win32/sixxpack" ascii wide nocase
        $s6 = "trojan.sixxpack" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Sixxpack (Trojan) Execution & Triage
id: 1333429a-dfc4-515d-8d35-e09ed0ee6560
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Sixxpack 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/sixxpack
- 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.t1055
- attack.t1027
- 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_SIXXPACK_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Sixxpack 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 = "sixxpack" 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 the affected workstation from internal network segments immediately.
2. Inspect running instances of svchost.exe and explorer.exe for hollowed memory regions.
3. Remove startup keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run pointing to Sixxpack.
4. Block outbound C2 IP addresses and domains across perimeter firewalls and DNS resolvers.
5. Perform an enterprise endpoint detection and response (EDR) scan to eliminate secondary payloads.

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 system to communicate outbound to external networks during triage.
2. Do not assume simple file deletion terminates hollowed background processes in memory.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Kura
• Hyperbro
• Casbaneiro
• Siscos
• A8P9Eklc
• Gamehuck
• Joker
• Fenomengame

Machine-readable

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