{
  "family": "eitu",
  "sample_count": 1,
  "category": "ransomware",
  "description": "Adware:Win32/Eitu is a highly intrusive adware family designed to hijack the user's web browsing experience. Its primary goal is monetization through forced ad impressions and affiliate link redirection. Eitu specifically targets the browser's core components, injecting advertisements directly into web pages and altering default search settings without user consent (`T1189`).<br><br><b>Understanding Eitu (Browser Hijacking)</b><br>To an end-user, Eitu makes the internet nearly unusable. Legitimate search results are replaced with sponsored links, random text on web pages is turned into hyperlinks, and large banner ads obscure actual content. For an IT department, Eitu is a security risk because the adware networks it uses are often compromised, serving as vectors for more severe malware like ransomware or credential stealers (malvertising).<br><br><b>Execution and Hijacking Mechanics</b><br>Eitu is typically distributed via pay-per-install (PPI) networks, bundled with freeware or deceptive 'update' prompts. Upon execution, it installs itself as a Windows Service or Scheduled Task to ensure persistence (`T1543.003`). It then drops malicious extensions into Chrome, Edge, and Firefox. To prevent easy removal, Eitu often modifies the Windows Registry (specifically the `ExtensionInstallForcelist` policies for Chrome/Edge) (`T1562.001`), locking the extension so the user cannot uninstall it via the browser UI.<br><br><b>Indicators of Compromise & Impact</b><br>The primary impact is the unauthorized monetization of user data and exposure to secondary malware. Host-based IoCs include the presence of unexpected browser extensions (often with random alphanumeric IDs), unauthorized modifications to browser policy registry keys (`HKLM\\Software\\Policies\\Google\\Chrome`), and unexpected executables running from `%LocalAppData%`. Network IoCs involve constant, high-volume background HTTP/HTTPS requests to known advertising networks and tracking domains.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Eitu and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Eitu 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 Eitu establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Eitu 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 Eitu compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Eitu 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 Eitu employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Eitu 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 Eitu, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Eitu 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": [
    "T1189",
    "T1562.001",
    "T1543.003"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1189",
      "name": "Drive-by Compromise (Initial distribution via deceptive software bundles)",
      "tactic": "Initial Access"
    },
    {
      "id": "T1562.001",
      "name": "Impair Defenses: Disable or Modify Tools (Modifying browser policies to prevent adware removal)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1543.003",
      "name": "Create or Modify System Process: Windows Service (Establishing persistent adware updaters)",
      "tactic": "Persistence"
    }
  ],
  "containment_steps": [
    "Use a specialized Adware/Malware removal tool to identify and strip out the persistent registry keys and services protecting Eitu.",
    "Manually inspect and remove any forced browser policies (`chrome://policy` or `edge://policy`) that prevent extension removal.",
    "Reset all installed web browsers to their default, factory settings to clear out hijacked search engines and proxy configurations.",
    "Implement endpoint application control to block the execution of common, known adware installers from user directories."
  ],
  "what_to_avoid": [
    "Do not rely solely on the browser's 'Uninstall Extension' button; Eitu's background service will simply reinstall it.",
    "Avoid downloading 'free' software from third-party download portals, as they are the primary distribution vector for bundled adware."
  ],
  "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,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}