{
  "family": "pyme",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nPyme is a malicious program that exhibits characteristics of both a Trojan and a Worm. It is designed to covertly infiltrate Windows systems, establish a persistent backdoor, and then aggressively attempt to propagate itself across local networks or via removable media, creating a disruptive and potentially widespread security incident.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nPyme often infiltrates networks initially through malicious email attachments or when a user connects an already infected USB drive to a corporate workstation.\n\nUpon execution, Pyme focuses on persistence and propagation:\n<ul>\n<li><strong>Worm-like Propagation:</strong> Pyme actively scans the local subnet for open, unauthenticated file shares (SMB) or exploits legacy vulnerabilities to copy its executable laterally. It will also aggressively infect any connected removable media (USB drives), hiding legitimate files and replacing them with malicious shortcuts to facilitate further spread.</li>\n<li><strong>System Modification and Persistence:</strong> To ensure it runs every time the system boots, Pyme modifies the Windows Registry (e.g., adding entries to `HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run`). It may also disable built-in security features like Windows Defender or the Task Manager to protect itself from termination.</li>\n<li><strong>Backdoor Functionality:</strong> While spreading, Pyme often opens a covert backdoor, allowing remote attackers to issue commands, download secondary malware, or exfiltrate basic system data.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nA Pyme infection is highly disruptive. Its worm-like propagation capabilities can rapidly saturate a local network, causing significant downtime and overwhelming IT helpdesks. The backdoor functionality also presents a serious risk of data theft or the deployment of secondary, more destructive payloads like ransomware.\n\n<h3>Incident Response and Remediation</h3>\n<ul>\n<li><strong>Immediate Network Segmentation:</strong> Isolate infected subnets immediately to halt the worm's lateral movement and prevent the infection of mapped network drives.</li>\n<li><strong>Comprehensive Antivirus Sweep:</strong> Deploy an enterprise-grade anti-malware solution across the affected subnets to identify, quarantine, and remove the Pyme executable and its associated registry keys.</li>\n<li><strong>Removable Media Policy Review:</strong> Pyme's reliance on USB propagation strongly suggests that the organization's policies regarding removable media are either lacking or unenforced. Consider disabling USB storage access via Group Policy to prevent future outbreaks.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Worm.Pyme",
    "Trojan.Pyme",
    "Win32/Pyme"
  ],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Pyme and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Pyme is classified as a Ransomware. 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 Pyme establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Pyme 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 Pyme compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Pyme 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 cryptographic algorithms and file targeting techniques does Worm.Pyme employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Worm.Pyme typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options."
      }
    },
    {
      "@type": "Question",
      "name": "Are decryptors available for Worm.Pyme, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Worm.Pyme depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1059",
    "T1091",
    "T1547.001",
    "T1562.001"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "type": "Trojan / Worm",
  "target_industries": [
    "Healthcare",
    "Critical Infrastructure",
    "Enterprise"
  ],
  "motivation": "Financial Extortion",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "defense_evasion",
    "impact"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "mitre_attack_detail": [
    {
      "id": "T1059",
      "name": "Command and Scripting Interpreter",
      "tactic": "Execution"
    },
    {
      "id": "T1091",
      "name": "Replication Through Removable Media (The core propagation mechanism using autorun.inf)",
      "tactic": "Lateral Movement"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder",
      "tactic": "Persistence"
    },
    {
      "id": "T1562.001",
      "name": "Impair Defenses: Disable or Modify Tools",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Pyme from spreading laterally or encrypting network-attached storage (NAS) and shared SMB volumes.",
    "Preserve volatile system memory (RAM capture) on a representative endpoint before attempting a reboot or power-down, as Pyme symmetric encryption keys or uncompiled payload components may still reside in memory.",
    "Audit process execution logs and terminate active scripting interpreters (e.g. PowerShell, CMD, WScript) or commands executing 'vssadmin.exe delete shadows' or 'wbadmin' used by Pyme to inhibit recovery.",
    "Investigate the initial compromise vector (such as exposed RDP instances, spearphishing attachments, or vulnerable edge gateways) and enforce an immediate credential reset for all compromised Active Directory accounts.",
    "Restore critical assets and databases exclusively from verified, air-gapped, or immutable offline backups once the Pyme binary and related persistence hooks are eradicated."
  ],
  "what_to_avoid": [
    "Do not restart or power cycle infected systems prematurely; doing so destroys volatile RAM encryption keys and may trigger bootloader locking logic embedded in Pyme.",
    "Avoid negotiating or paying the extortion demand without prior forensic evaluation and consultation with incident response specialists, as payment does not guarantee data recovery.",
    "Do not connect clean backup drives or external storage to the affected network until Pyme eradication is completely verified."
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}