SquareX has revealed critical architectural flaws in browser Developer Tools (DevTools) that make it virtually impossible to detect and analyze malicious browser extensions at runtime. The disclosure comes amid rising concerns over extension-based spyware attacks, including the recent Geco Colorpick incident, which compromised over 2.3 million users despite bearing trusted “Verified” and “Chrome Featured” labels.
SquareX’s research identifies a growing blind spot in enterprise security strategies—browser extensions that operate outside the visibility of current DevTool-based inspection capabilities.
DevTools: Built for Websites, Blind to Extensions
Browser DevTools, developed in the late 2000s, were originally designed for debugging web pages—not monitoring extensions. Extensions, however, often operate at a system-like level with broad permissions, including the ability to inject scripts, capture screenshots, or make network calls that blend in with legitimate browser activity.
“Extensions are complex beasts,” said Nishant Sharma, Head of Security Research at SquareX. “They operate across tabs, behave dynamically, and can mask their actions from basic telemetry. DevTools simply weren’t built to analyze that level of sophistication.”
For instance, an extension can trigger a network request by injecting a script into a webpage. DevTools can’t distinguish whether the request was made by the page or the extension—rendering standard security auditing ineffective.
SquareX’s Proposed Solution: Extension Monitoring Sandbox
To bridge this gap, SquareX is introducing a new research-backed approach: the Extension Monitoring Sandbox, which comprises:
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Modified Browser Architecture: Custom-built to expose critical telemetry that current DevTools miss.
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Browser AI Agents: Simulate varied user personas and behaviors to elicit runtime actions from extensions, including those triggered by time delays, user interaction, or environmental variables.
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Dynamic Analysis Engine: Allows detection of “hidden” or conditional malicious behaviors embedded in extensions.
This multi-layered setup enables full behavioral monitoring and real-time security analysis of browser extensions—something SquareX says is crucial as extensions become deeply integrated into enterprise workflows.
Extension Labels Provide False Security
SquareX points to the Geco Colorpick case, where 18 spyware-laced extensions received “Verified” status and infiltrated millions of user environments. The company warns that relying on marketplace labels alone—such as those from Chrome Web Store or Edge Add-ons—is no longer sufficient for assessing risk.
“Millions are compromised because we’ve outgrown the security model of the browser,” SquareX notes in its blog. “Security teams need tools that account for dynamic, evasive behaviors—not just static metadata.”
Free Enterprise-Wide Extension Audit in August
To help organizations assess their current exposure, SquareX is offering a free extension audit throughout August. The audit includes:
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Metadata Analysis: Evaluates basic attributes like permissions, publisher history, and marketplace status.
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Static Code Analysis: Scans the extension’s codebase for risky patterns and known threats.
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Dynamic Runtime Analysis: Leverages the Extension Monitoring Sandbox to uncover hidden behaviors.
Organizations receive a detailed risk score for each installed extension, equipping IT and security leaders with actionable insights to guide policy and control decisions.
