{
  "family": "bsymem",
  "sample_count": 144,
  "category": "ransomware",
  "description": "Trojan:Win32/Bsymem is a stealthy, persistent trojan designed to silently infiltrate corporate networks, establish a persistent backdoor, and act as a reliable conduit for credential exfiltration and secondary payload delivery.<br><br><b>Understanding Bsymem</b><br>For the victim, Bsymem provides zero visual indicators of compromise. For threat intelligence analysts, Bsymem represents a highly capable Remote Access Trojan (RAT). It is designed to bypass endpoint defenses, harvest system information, and establish a covert Command-and-Control (C2) channel to receive further instructions or download severe secondary payloads like ransomware.<br><br><b>Execution and Evasion Strategies</b><br>Bsymem is typically delivered via spearphishing campaigns containing malicious attachments or dropped as a secondary payload by exploit kits. Upon execution, it utilizes heavy packing and obfuscation to evade static antivirus signatures. It drops a randomized executable into the <code>%AppData%</code> or <code>%SystemRoot%</code> directories. Persistence is achieved by creating a hidden scheduled task or modifying the Registry Run keys. Bsymem frequently injects its core modules into legitimate system processes (like <code>svchost.exe</code>) to mask its outbound network traffic.<br><br><b>Indicators of Compromise (IoCs)</b><br>Threat hunters should investigate EDR alerts for 'Suspicious Process Injection' or 'Anomalous Child Process Spawning'. Network logs will often reveal Bsymem reaching out to compromised domains using encrypted HTTP/HTTPS traffic. The presence of unexpected, hidden scheduled tasks designed to execute randomly named binaries in the user's profile is a strong IoC. Memory analysis is crucial to extract the injected modules and identify the specific C2 infrastructure.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1053.005",
    "T1105",
    "T1027",
    "T1055",
    "T1547.001"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1055",
      "name": "Process Injection",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer",
      "tactic": "Command and Control"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder",
      "tactic": "Persistence"
    },
    {
      "id": "T1053.005",
      "name": "Scheduled Task/Job: Scheduled Task",
      "tactic": "Persistence"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Instantly isolate the endpoint from the network to sever the attacker's interactive, remote-control session.",
    "Capture a full forensic memory image of the machine to extract the decrypted Bsymem payload and its C2 configuration.",
    "Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Bsymem persistence mechanisms.",
    "Assume total endpoint compromise; perform a clean OS rebuild and force password resets for all accounts that accessed the machine."
  ],
  "what_to_avoid": [
    "Do not leave the machine connected to the network during triage; the attacker has live access and will likely destroy evidence or move laterally.",
    "Avoid relying solely on manual file deletion, as the injected processes will likely just recreate the dropped binaries."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}