Security researchers have uncovered a new malware toolkit known as Stanley, sold on Russian cybercrime forums, that uses malicious browser extensions to silently redirect users to phishing websites while keeping the legitimate URL visible in the address bar.

The malware is marketed as a premium toolkit, priced between $2,000 and $6,000, and is advertised as capable of bypassing Google Chrome Web Store moderation.

How the Stanley Malware Works

Unlike traditional phishing attacks, Stanley operates through a browser extension that injects malicious content directly into legitimate websites.

This technique allows attackers to present fake login forms or payment pages while the browser continues to display the correct domain name, making the attack extremely difficult for users to detect.

Underground Marketplace Listing

Stanley malware marketplace listing on a Russian cybercrime forum Stanley Chrome extension spoofing a legitimate website
ource · Varonis — Stanley marketplace listing on a Russian forum

The toolkit is actively promoted on underground marketplaces, with sellers claiming escrow support, frequent updates, and compatibility with Chrome-based browsers.

Malicious Extension in Action

Stanley Chrome extension spoofing a legitimate website Stanley Chrome extension spoofing a legitimate website Stanley Chrome extension spoofing a legitimate website
Source · Varonis — Malicious Chrome extension website spoofing

Once installed, the extension can selectively target banking portals, cryptocurrency services, email providers, and enterprise login pages, harvesting credentials and sensitive data in real time.

Why This Attack Is Dangerous

What Users Should Do

Sources & References

This article was written for DigitalEscapeTools based on independent security research and publicly available threat intelligence.