Computty

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Credential Harvesting: The core malicious functionality is to intercept the usernames, passwords, and SSH private keys entered by the administrator when authenticating to a remote server.
• Covert Exfiltration: The stolen credentials are silently logged and periodically transmitted to an attacker-controlled command-and-control (C2) server, usually over HTTP or SMTP to blend in with normal traffic.
• Evasion: Because the underlying code is the legitimate PuTTY client, the backdoored executable often evades basic signature-based antivirus detection, appearing as a standard administrative tool.

Threat Assessment

Incident Response and Remediation

• Immediate Global Key Rotation: If a modified PuTTY executable is discovered, assume that every server the administrator connected to has been compromised. Immediately revoke and regenerate all SSH keys and passwords associated with that administrator.
• Endpoint Sweeps and File Hashing: Utilize enterprise EDR to sweep the network for the specific hash of the modified PuTTY binary. Remove the malicious executable and enforce the usage of centrally deployed, verified IT tools.
• Network Segmentation and MFA: Enforce Multi-Factor Authentication (MFA) for all administrative SSH connections, ensuring that stolen credentials alone are insufficient for access.

Known aliases

Threat reports may refer to this family under multiple names:

• HackTool.PuTTY
• Trojan.PuTTY.Modified
• PWS.PuTTY

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.

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_COMPUTTY_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Computty"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "computty" ascii wide nocase
        $s2 = "hacktool.putty" ascii wide nocase
        $s3 = "trojan.putty.modified" ascii wide nocase
        $s4 = "pws.putty" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Computty (Trojan) Execution & Triage
id: 83f77af8-1d95-580b-b26c-fdd469e89e39
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Computty 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/computty
- 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.t1552_004
- attack.t1056_001
- attack.t1556
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_COMPUTTY_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Computty 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 = "computty" 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 network connectivity for the flagged endpoint to terminate persistent command-and-control (C2) communication channels and stop Computty from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Computty into legitimate system processes such as explorer.exe or svchost.exe.
3. Audit Windows Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) and Task Scheduler entries to locate and purge Computty persistence hooks.
4. Deploy updated enterprise EDR detection signatures and conduct an out-of-band endpoint scan to isolate dropped binaries and staged payloads.
5. Rotate all credentials, domain user passwords, and session cookies active on the system during the Computty execution timeframe.

What to Avoid

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

1. Do not assume the incident is resolved simply because an antivirus tool removed the initial Computty dropper; always verify that secondary payloads and persistence hooks have been eradicated.
2. Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Computty until memory triage is complete.
3. Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution.

References & External Analysis

• Search "computty" on VirusTotal (External Analysis)
• Search "computty" on Any.Run (Sandbox Sandbox)
• Search "computty" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Harvester
• Gamania
• Y3K_Rat
• Synrat
• Jbonblanc
• Pwszbot
• Winsecsrv
• Runner

Machine-readable

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