SquareX recently revealed an alarming attack technique involving browser extensions that can take over a device with minimal user interaction. This new discovery undermines prior assumptions that browser extensions couldn’t gain full control over browsers or devices. The research shows that by exploiting the permissions granted to many common extensions, such as Grammarly or Calendly, attackers can escalate privileges to hijack both the browser and the entire device. The attack begins with an innocent-looking extension that silently authenticates the victim’s browser profile to the attacker’s Google Workspace, giving them the ability to control browser settings and policies, including disabling safe browsing features.
The malicious extension then performs a sophisticated social engineering attack, prompting the victim to sync their browser profile with an attacker-controlled account.
Once synced, attackers gain access to all stored credentials and browsing history, bypassing traditional security monitoring tools due to the legitimate nature of the sites used in the attack. Following this, the extension takes control of the browser by replacing a legitimate update, such as a Zoom installer, with a malicious executable that turns the browser into a “managed” device under the attacker’s control. This allows attackers to disable security features, install more malware, or redirect users to phishing sites.
The final phase of the attack involves device hijacking, where the extension uses the downloaded file to insert registry entries that let it interact with local applications, such as activating the device’s camera, capturing audio, or recording the screen. These interactions give attackers full control over the device, compromising sensitive data and enabling additional malicious activity. The browser syncjacking attack exposes serious flaws in how remote-managed profiles and browsers are handled, as anyone can create a managed workspace account and link it to a malicious extension without identity verification.
SquareX’s research highlights a critical blind spot in enterprise security, revealing how current tools are ill-equipped to detect and block such sophisticated browser-based attacks. This technique bypasses traditional security measures like EDRs and web gateways, making it particularly dangerous for enterprises. The researchers emphasize the need for Browser Detection-Response solutions to offer better visibility and control over browser extensions, as existing measures are insufficient to protect against these emerging threats.
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