How the Extension Intercepted Searches
Microsoft’s Defender research team uncovered a malicious Chrome extension disguised as the AI search engine Perplexity. Named “Search for perplexity ai” and hosted on a look-alike domain, the extension hijacked the browser’s search functionality. Upon installation, it set itself as the default search engine, routing every user query through an attacker-controlled server before redirecting to legitimate results. This allowed the extension to log searches along with browser headers, IP addresses, and user agent data.
Expanded Data Collection via Address Bar
The extension went beyond intercepting completed searches. It also redirected live search suggestions typed into the address bar to the attacker’s server, capturing keystrokes in real time. It requested broad permissions including declarativeNetRequest APIs and included disabled redirect rules for other search engines, indicating a planned expansion. Microsoft noted the extension also contained code for future WebAssembly execution, confirming its malicious intent was more than a simple redirect.
Defensive Measures and Broader Context
Google removed the extension from the Chrome Web Store after Microsoft’s responsible disclosure. The campaign fits a pattern of malicious extensions exploiting AI branding, following past incidents involving ChatGPT and DeepSeek targeting chat sessions. This variant focused on search interception rather than chat skimming. Users who installed the extension should remove it and verify their default search engine settings. Organizations are advised to restrict extensions to an approved list, monitor for changed settings, and treat AI-branded tools with caution.
Source: The Hacker News
