TechHorizon Consulting

Syncjacking: The Hidden Danger of Malicious Chrome Extensions

Feb 04, 2025By Eli Junco

EJ

Cybercriminals are constantly evolving their tactics, and a new attack method called Syncjacking has emerged as a serious threat. This attack leverages seemingly harmless Chrome extensions to hijack browsers and even entire devices, putting sensitive data at risk. In this post, we’ll break down what Syncjacking is, how it works, and what you can do to protect yourself.

What Is Syncjacking?


Syncjacking is a cyberattack that exploits Chrome’s browser sync feature through malicious extensions. Attackers use this method to:

  • Hijack Google profiles by tricking users into syncing with an attacker-controlled account.
  • Gain access to stored data, including passwords, browsing history, and cookies.
  • Take control of browsers and devices, allowing them to install malware, modify files, and monitor user activity.
  • Often times developers don't even know their extensions have been compromised. 
cyber hacker attacks concept.

A Real-World Example: How the Attack Works


Recent research by SquareX Labs uncovered how cybercriminals use Syncjacking to hijack Chrome browsers and entire devices. Here’s how the attack unfolds:

  1. Creation of a Malicious Extension
    1. Attackers develop and publish a seemingly legitimate Chrome extension on the Chrome Web Store.
    2. The extension has minimal permissions, making it appear safe.
  2. Tricking the User
    1. Attackers use social engineering techniques to convince users to install the extension. This might involve phishing emails, fake advertisements, or deceptive pop-ups that promote the extension as a useful tool.
    2. Victims might be led to a professional-looking website claiming the extension enhances browser functionality, speeds up performance, or improves security.
    3. Some users may install the extension unknowingly as part of a bundled software package or through a misleading prompt.
  3. Sync Hijacking
    1. Once installed, the extension runs silently in the background, connecting the victim to an attacker-controlled Google profile.
    2. The extension injects misleading content into a legitimate Google support page, instructing the victim to enable Chrome Sync.
    3. Believing this is a routine security step, the victim enables sync, unknowingly transferring all saved passwords, browsing history, and other synced data to the attacker.
  4. Full Browser and Device Takeover
    • The attacker escalates control by presenting a fake software update that prompts the user to download malware.
    • Once installed, this malware grants the attacker full control over the victim's browser and, in some cases, the entire device.
    • Using Chrome’s Native Messaging API, attackers can execute commands, install malware, and even activate the victim's webcam and microphone.
Computer security and extortion


How to Protect Against Syncjacking Attacks


Given the stealthy nature of this attack, taking proactive security measures is essential. Here’s how you can stay safe:

  1. Be Cautious When Installing Extensions
    • Only install Chrome extensions from well-known developers and read user reviews.
    • Regularly review and remove unnecessary extensions.
  2. Disable Chrome Sync for Sensitive Accounts
    • Avoid enabling Chrome Sync on devices that handle sensitive business or personal information.
  3. Monitor Browser Activity
    • Regularly check your Chrome settings for Managed Browser labels, which indicate external control.
    • Pay attention to unexpected logins or sync requests.
    • Ensure that employees only download approved Chrome Extensions
  4. Use Security Tools
    • Implement endpoint security solutions that can detect and block malicious extensions.
    • Use browser-native security tools that analyze extension behavior in real time.
  5. Stay Updated
    • Keep your browser and security software up to date to protect against known vulnerabilities.

Staying Ahead of Cyber Threats


Keeping up with the constantly evolving landscape of cyber threats is a challenge for any business. New attack methods, like Syncjacking, demonstrate just how quickly cybercriminals adapt to exploit vulnerabilities. At TechHorizon Consulting, we have the expertise and advanced security solutions to help you stay protected.

Our vCISO services, extension monitoring tools, and cybersecurity assessments can safeguard your business against browser-based attacks and other emerging threats. Whether you need help enforcing security policies, monitoring for malicious activity, or responding to cyber incidents, we are here to assist.