{
  "family": "bayrob",
  "sample_count": 74,
  "category": "trojan",
  "description": "Trojan:Win32/Bayrob is a highly sophisticated, persistent trojan that historically targeted users of online auction sites (like eBay) and e-commerce platforms, designed to intercept traffic, spoof web pages, and facilitate high-value financial fraud.<br><br><b>Understanding Bayrob</b><br>To the victim, a Bayrob infection might seem like a standard, albeit glitchy, web browsing experience. However, when the victim visits a targeted e-commerce site, Bayrob intercepts the connection. For security analysts, Bayrob is a classic 'Man-in-the-Browser' (MitB) threat. It was famously used to spoof vehicle auctions; a victim would believe they were bidding on a legitimate car on a real site, but Bayrob was rewriting the HTML in real-time, redirecting payment details to the attackers.<br><br><b>Execution and Evasion Strategies</b><br>Bayrob was historically distributed via massive, highly targeted spearphishing campaigns, often utilizing macro-enabled Word documents. Upon execution, the payload establishes deep persistence, often operating as a hidden system service or injecting itself into `explorer.exe`. Bayrob's primary capability is functioning as a local proxy server. It modifies the victim's registry and network settings to route all HTTP/HTTPS traffic through its own engine, allowing it to inspect, modify, or block traffic. It uses custom encryption protocols to communicate with its C2 servers, downloading updated 'web injects' (HTML templates used to spoof target sites).<br><br><b>Indicators of Compromise & Impact</b><br>The impact is severe financial fraud and credential theft. Incident responders will observe anomalous proxy configurations in the Windows Registry or browser settings. Network logs may show heavy, encrypted traffic over non-standard ports to compromised domains. EDR platforms will flag the unauthorized injection of code into browsers (`chrome.exe`, `firefox.exe`) or the unexpected creation of local proxy listeners.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1566.001",
    "T1055",
    "T1543.003",
    "T1090.001",
    "T1185"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1185",
      "name": "Browser Session Hijacking",
      "tactic": "Collection"
    },
    {
      "id": "T1566.001",
      "name": "Phishing: Spearphishing Attachment",
      "tactic": "Initial Access"
    },
    {
      "id": "T1090.001",
      "name": "Proxy: Internal Proxy",
      "tactic": "Command and Control"
    },
    {
      "id": "T1543.003",
      "name": "Create or Modify System Process: Windows Service",
      "tactic": "Persistence"
    },
    {
      "id": "T1055",
      "name": "Process Injection",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Immediately isolate the endpoint from the network to sever the local proxy interception and halt the exfiltration of credentials.",
    "Audit the system's local proxy settings (e.g., `Internet Options -> Connections -> LAN settings`) and remove any malicious entries pointing to `127.0.0.1`.",
    "Capture a full forensic memory image to extract the active Bayrob payload and the web inject configurations it currently holds in RAM.",
    "Assume all credentials and financial data entered on the machine have been compromised; initiate mandatory password resets."
  ],
  "what_to_avoid": [
    "Do not trust the integrity of any web session initiated from the infected machine; Bayrob actively alters the HTML presented to the user.",
    "Avoid relying solely on basic AV scans; the deep system hooks often require manual registry and service remediation."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}