{
  "family": "bancos",
  "sample_count": 55,
  "category": "trojan",
  "description": "TrojanDownloader:Win32/Bancos is a massive, highly prolific family of banking trojans that historically originated from, and almost exclusively targeted, users in Brazil. It is engineered to monitor browsing activity, detect when a user visits targeted Latin American financial institutions, and steal their banking credentials.<br><br><b>Understanding Bancos</b><br>To the victim, a Bancos infection is invisible until their bank account is mysteriously drained. For threat intelligence analysts, Bancos represents a highly localized, deeply entrenched criminal ecosystem. Brazilian threat actors continually iterate on Bancos, making it a cat-and-mouse game for AV vendors. It differs from sophisticated, global trojans (like Zeus) by often relying on simpler, yet highly effective, social engineering and web overlays rather than complex rootkits.<br><br><b>Execution and Evasion Strategies</b><br>Bancos is primarily distributed via massive, localized malspam campaigns (phishing emails written in Portuguese, often impersonating Brazilian tax authorities, utilities, or banks). The emails contain links to ZIP files or malicious executables. Upon execution, Bancos establishes persistence (Registry Run keys or scheduled tasks). It continuously monitors the active browser window title or URL (`T1185`). When a targeted Brazilian bank is detected, Bancos springs into action. It often uses localized DNS hijacking (`T1568.002`) or simply drops a fake, full-screen HTML overlay over the legitimate banking site, tricking the user into entering their credentials, CPF (Brazilian taxpayer registry), and two-factor authentication tokens, which are immediately POSTed to the attacker's server.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is severe, targeted financial fraud. Incident responders will observe anomalous outbound traffic to C2 servers, often hosted on compromised Brazilian infrastructure. EDR platforms will flag the malware monitoring browser APIs or modifying the local `HOSTS` file to redirect banking URLs. The presence of newly dropped, heavily packed executables in `%AppData%` originating from email clients is a strong IoC.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1056.001",
    "T1568.002",
    "T1048",
    "T1185",
    "T1566.001"
  ],
  "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": "T1056.001",
      "name": "Input Capture: Keylogging",
      "tactic": "Collection"
    },
    {
      "id": "T1568.002",
      "name": "Dynamic Resolution: Domain Generation Algorithms",
      "tactic": "Command and Control"
    },
    {
      "id": "T1048",
      "name": "Exfiltration Over Alternative Protocol",
      "tactic": "Exfiltration"
    }
  ],
  "containment_steps": [
    "Immediately isolate the endpoint from the network to halt the active credential harvesting and prevent the attacker from maintaining a live session with the bank.",
    "Assume all financial credentials used on the machine are compromised; initiate mandatory password resets and contact relevant banking institutions immediately.",
    "Capture a forensic memory image to extract the active Bancos configuration, identifying exactly which financial institutions were targeted.",
    "Due to the aggressive credential harvesting, a complete, clean rebuild of the operating system is the most secure remediation."
  ],
  "what_to_avoid": [
    "Do not allow the user to type any passwords or access sensitive portals while the machine is infected.",
    "Avoid relying solely on basic AV removal, as Bancos frequently updates its persistence mechanisms and drops secondary payloads."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}