How Phantom Shuttle Chrome Extensions Undermined Enterprise Security with Man-in-the-Middle Attacks
In December 2025, cybersecurity researchers discovered two versions of a Google Chrome extension named 'Phantom Shuttle' that secretly intercepted network traffic and stole user credentials from over 170 targeted domains. Masquerading as a legitimate VPN and speed test tool, these browser add-ons leveraged proxy permissions and malicious JavaScript code to inject authentication credentials and enable man-in-the-middle attacks. Users paid for subscriptions believing they were purchasing a secure service, while in reality, their web traffic, including passwords, authentication cookies, credit card information, API keys, and browsing histories, was exfiltrated continuously to a threat actor-controlled command-and-control server. The operation leveraged a subscription model and payment integrations via Alipay and WeChat, while traffic was routed through threat actor proxies managed via PAC scripts. This incident highlights a growing trend of browser extension abuse, with attackers monetizing malicious add-ons under the guise of productivity or security tools. With enterprise users increasingly utilizing browser extensions for business workflows, unmanaged browser risk is rapidly becoming a critical threat to organizational data security and compliance.
Kill Chain
