{
  "family": "computty",
  "sample_count": 1,
  "category": "trojan",
  "description": "<h3>Executive Summary</h3>\nComputty (often detected as HackTool.PuTTY.Modified or Trojan.PuTTY) is a malicious modification of the legitimate, highly popular open-source SSH and Telnet client, PuTTY. Threat actors take the legitimate PuTTY source code, inject malicious functionality (usually a credential stealer or a backdoor), recompile it, and distribute it to system administrators, allowing the attackers to intercept highly privileged authentication credentials.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nThe modified PuTTY executable is typically distributed via spear-phishing campaigns targeting IT staff, or by hosting the backdoored software on lookalike \"typosquatting\" domains designed to mimic the official PuTTY download page.\n\nUpon execution, the tool functions exactly like the legitimate PuTTY client, allowing the administrator to successfully connect to remote servers. However, it operates with severe malicious intent:\n<ul>\n<li><strong>Credential Harvesting:</strong> The core malicious functionality is to intercept the usernames, passwords, and SSH private keys entered by the administrator when authenticating to a remote server.</li>\n<li><strong>Covert Exfiltration:</strong> 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.</li>\n<li><strong>Evasion:</strong> 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.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nThe compromise of an administrative tool like PuTTY is a catastrophic security incident. By stealing SSH credentials, the attackers gain direct, highly privileged access to the organization's core infrastructure (Linux servers, firewalls, routers), entirely bypassing perimeter defenses and multi-factor authentication (if keys are stolen).\n\n<h3>Incident Response and Remediation</h3>\n<ul>\n<li><strong>Immediate Global Key Rotation:</strong> 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.</li>\n<li><strong>Endpoint Sweeps and File Hashing:</strong> 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.</li>\n<li><strong>Network Segmentation and MFA:</strong> Enforce Multi-Factor Authentication (MFA) for all administrative SSH connections, ensuring that stolen credentials alone are insufficient for access.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "HackTool.PuTTY",
    "Trojan.PuTTY.Modified",
    "PWS.PuTTY"
  ],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Computty and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Computty is classified as a Trojan. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments."
      }
    },
    {
      "@type": "Question",
      "name": "How does Computty establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Computty typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks."
      }
    },
    {
      "@type": "Question",
      "name": "What are the essential incident response steps for mitigating a Computty compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Computty should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups."
      }
    },
    {
      "@type": "Question",
      "name": "What secondary payloads and staging behaviors are commonly associated with HackTool.PuTTY?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "HackTool.PuTTY frequently operates as a loader or dropper designed to establish a foothold before downloading and executing secondary high-impact malware payloads. Depending on the threat actor's objectives, these dropped modules can range from ransomware and banking injects to modular infostealers and remote management backdoors."
      }
    },
    {
      "@type": "Question",
      "name": "How can security operations teams effectively detect and hunt for HackTool.PuTTY across enterprise endpoints?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Defenders should hunt for HackTool.PuTTY by deploying behavioral endpoint detection and response (EDR) rules that monitor suspicious process spawning (such as cmd.exe or powershell.exe spawned from office documents or temporary directories), anomalous outbound network connections from non-browser binaries, and unauthorized modifications to Windows Run keys and scheduled task registries."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1552.004",
    "T1056.001",
    "T1556"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "type": "HackTool / Credential Stealer",
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "execution",
    "persistence"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "mitre_attack_detail": [
    {
      "id": "T1552.004",
      "name": "Unsecured Credentials: Private Keys",
      "tactic": "Credential Access"
    },
    {
      "id": "T1056.001",
      "name": "Keylogging",
      "tactic": "Credential Access"
    },
    {
      "id": "T1556",
      "name": "Modify Authentication Process",
      "tactic": "Credential Access"
    }
  ],
  "containment_steps": [
    "Sever network connectivity for the flagged endpoint to terminate persistent command-and-control (C2) communication channels and stop Computty from retrieving secondary stage payloads.",
    "Capture process memory triage to detect and terminate malicious threads injected by Computty into legitimate system processes such as explorer.exe or svchost.exe.",
    "Audit Windows Registry Run keys (HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run) and Task Scheduler entries to locate and purge Computty persistence hooks.",
    "Deploy updated enterprise EDR detection signatures and conduct an out-of-band endpoint scan to isolate dropped binaries and staged payloads.",
    "Rotate all credentials, domain user passwords, and session cookies active on the system during the Computty execution timeframe."
  ],
  "what_to_avoid": [
    "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.",
    "Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Computty until memory triage is complete.",
    "Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution."
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows 7"
  ]
}