Anthropic Claude Desktop Implants Browser Bridge, Bypassing Sandboxes

Anthropic’s Claude Desktop application for macOS covertly installs a Native Messaging bridge for web browsers, according to findings by security researcher Alexander Hanff, as reported by Cyber Updates - Asher Tamam. This installation occurs without user consent and targets up to seven different browsers, irrespective of whether they are installed on the system.

This persistent component reinstalls itself upon application restart if manually removed, a behavior Cyber Updates - Asher Tamam likens to malware. Functionally, this bridge grants Anthropic—or an attacker exploiting a vulnerability in their extension—direct access to browser internals. This includes the ability to read the DOM tree, capture real-time passwords, credit card details, and private messages, effectively bypassing browser sandboxing and HTTPS encryption.

This design decision, whether intentional ‘spyware’ or severe engineering negligence, prioritizes user experience over fundamental security, leaving macOS users exposed to significant data exfiltration risks. CISOs must recognize this as a critical attack surface, as it undermines core browser security mechanisms designed to protect sensitive user data.