{
  "family": "lozer",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nLozer is a malicious Trojan designed to covertly infiltrate Windows systems, establish deep persistence, and act as a reliable backdoor for remote threat actors. Frequently distributed in targeted spear-phishing campaigns, Lozer is often the primary initial access mechanism used to facilitate the deployment of secondary, high-impact malware payloads such as ransomware or enterprise info-stealers.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nLozer is predominantly distributed through socially engineered spam campaigns containing malicious attachments (often weaponized PDFs or Office documents utilizing macro exploits) or via compromised software installers downloaded from untrustworthy web portals.\n\nUpon successful execution, Lozer operates with a focus on stealth and payload delivery:\n<ul>\n<li><strong>System Reconnaissance:</strong> The trojan immediately collects detailed system information, including the OS version, installed software, Active Directory domain membership, and active antivirus solutions. This fingerprint is transmitted to a command-and-control (C2) server.</li>\n<li><strong>Persistence:</strong> Lozer ensures it survives system reboots by modifying the Windows Registry (e.g., adding entries to the `Run` or `RunOnce` keys) or by creating hidden Scheduled Tasks that execute the malware payload under high privileges.</li>\n<li><strong>Command Execution:</strong> Acting as a backdoor, Lozer provides the attacker with a remote shell, allowing them to execute arbitrary system commands, manipulate the file system, and silently download and deploy secondary malware.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nA Lozer infection represents a critical breach of the endpoint perimeter. Because it provides remote attackers with interactive access and the ability to execute arbitrary code, a single compromised machine can rapidly be utilized to pivot laterally and compromise the entire corporate network.\n\n<h3>Remediation and Eradication</h3>\n<ul>\n<li><strong>Endpoint Detection and Response (EDR):</strong> Configure EDR solutions to monitor for anomalous registry modifications and unauthorized outbound network connections to unknown IP addresses.</li>\n<li><strong>Network Isolation and Sweeps:</strong> Immediately isolate the infected endpoint from the LAN. Conduct a thorough forensic sweep to identify not only the Lozer executable but also any secondary payloads it may have successfully deployed.</li>\n<li><strong>Credential Reset:</strong> Because Lozer provides an interactive backdoor, all user credentials and active session tokens associated with the compromised endpoint must be treated as compromised and immediately reset.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Trojan.Lozer",
    "Backdoor.Lozer",
    "Win32/Lozer"
  ],
  "enrichment_level": "insufficient_information",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1105",
    "T1547.001",
    "T1059"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-07-01T16:35:09Z",
  "type": "Trojan",
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}