{
  "family": "yiwanzhushou",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nYiwanzhushou is an aggressive Potentially Unwanted Program (PUP) and Adware application that operates primarily as a Browser Hijacker. It masquerades as a helpful browser extension, search optimizer, or coupon finder. Its true purpose is to forcefully inject advertisements, alter critical browser settings, and heavily monetize the infected endpoint through affiliate traffic generation and data harvesting.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nYiwanzhushou relies almost entirely on deceptive software bundling. Users typically encounter it when downloading \"free\" software from unofficial, localized web portals or third-party aggregators. The adware is installed silently in the background during the primary software's setup process, often utilizing deceptive \"Advanced\" or \"Custom\" installation screens.\n\nOnce installed, the software employs highly aggressive tactics:\n<ul>\n<li><strong>Aggressive Browser Hijacking:</strong> The software installs persistent extensions across Chrome, Firefox, and Edge. It forcefully modifies the default homepage, search engine, and new tab page to route all traffic through affiliate-monetized search engines controlled by the adware developers.</li>\n<li><strong>System Watchdogs and Rootkit Tactics:</strong> Yiwanzhushou frequently installs background \"watchdog\" services that actively monitor the registry and browser settings. If a user attempts to remove the extension or change their homepage back to a legitimate search engine, the watchdog service instantly reinstalls the adware configurations.</li>\n<li><strong>Ad Injection and Overlay:</strong> It injects its own JavaScript into legitimate websites, overlaying pages with intrusive pop-up ads, sliding banners, and embedded video advertisements, significantly degrading system performance and user experience.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nWhile Yiwanzhushou is generally not classified as destructive malware (like ransomware), it poses a severe threat to system stability, user productivity, and privacy. The aggressive persistence mechanisms cause significant IT overhead, and the constant ad injection consumes massive CPU and RAM resources. The tracking telemetry also violates corporate privacy policies.\n\n<h3>Incident Response and Remediation</h3>\n<ul>\n<li><strong>Safe Mode and Process Termination:</strong> Due to the aggressive watchdog services, it is often necessary to boot the infected machine into Windows \"Safe Mode\" to prevent the adware's defense mechanisms from launching before attempting uninstallation.</li>\n<li><strong>Targeted Anti-Malware Scan:</strong> Standard antivirus often ignores PUPs. Utilize a reputable enterprise anti-malware solution (specifically tuned for Adware removal) to scan for and remove the deeply embedded registry keys and scheduled tasks.</li>\n<li><strong>Browser Factory Reset:</strong> Following the removal of the underlying files, a full factory reset of all installed web browsers is absolutely required to purge the malicious extensions and hijacked settings.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Adware.Yiwanzhushou",
    "PUP.Yiwanzhushou",
    "Win32/Adware.Hijacker"
  ],
  "enrichment_level": "insufficient_information",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1185",
    "T1176",
    "T1546.015"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-07-02T06:57:41Z",
  "type": "Adware / Browser Hijacker",
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}