Introduction
Security researchers have recently identified a novel attack technique termed “browser syncjacking.” This method enables malicious browser extensions to gain complete control over a targeted browser and device with minimal user interaction. The attack leverages permissions typically granted to extensions, particularly those posing as legitimate productivity tools, and unfolds in three main phases: profile hijacking [4] [7], browser takeover [1] [3] [4] [5] [7] [8] [9], and device hijacking [1] [3] [4] [6] [7] [10].
Description
Security researchers have identified a newly disclosed attack technique known as “browser syncjacking,” which allows malicious extensions to take full control of a targeted browser and device with minimal user interaction [6] [10]. This method exploits the permissions commonly granted to browser extensions available on the Chrome Store [3] [4] [7] [8], particularly those that masquerade as legitimate productivity tools and often require read/write capabilities. The attack unfolds in three main phases: profile hijacking, browser takeover [1] [3] [4] [5] [7] [8] [9], and device hijacking [1] [3] [4] [6] [7] [10].
In the first phase [3], an employee unknowingly installs a seemingly benign Chrome extension that may either impersonate a legitimate tool or take over an existing popular extension. This extension executes a silent authentication process, automatically signing the user into a rogue Chrome profile managed by a malicious Google Workspace domain created by the attacker, which has disabled security features [1] [2] [3] [4] [5] [6] [7] [8] [10]. This process is automated and nearly imperceptible [1] [3], as the extension operates in the background and manipulates trusted domains, such as Google’s support page [5], to prompt the victim to enable Chrome sync [2]. Once authenticated [8], the attacker can enforce harmful policies that disable security measures [8], such as Safe Browsing, and employ social engineering tactics to steal sensitive information, including passwords and browsing history [1] [2]. The sync process grants the attacker access to all stored credentials [4] [5], further compromising the victim’s security.
The second phase involves converting the victim’s Chrome browser into a managed browser [3] [4] [7]. The malicious extension intercepts legitimate downloads [3] [6] [7] [10], replacing them with the attacker’s executables [3] [6] [7], which install registry entries to manage the browser [3] [4] [7]. This grants the attacker extensive control [1] [6] [8] [10], allowing them to disable security measures [1] [3] [4] [5] [6] [7] [8] [10], install additional malicious extensions [1] [2] [3] [4] [5] [6] [7] [8] [9] [10], redirect users to phishing sites [1] [2] [3] [4] [5] [7] [8] [10], and facilitate data exfiltration. Attackers can also replace legitimate updates [9], such as those for Zoom [9], with malicious payloads [9]. Victims may receive a legitimate Zoom invitation [2], but clicking on it leads to the extension injecting malicious content that prompts an update download [2]. If executed, this file grants hackers complete control over the browser [1] [2], enabling them to access web apps [2], monitor or modify files [2], and further compromise the device.
The final phase encompasses device hijacking, where the malicious extension can communicate with local applications without further authentication [4] [6] [7]. This capability allows attackers to access the device’s camera [6] [10], microphone [1] [2] [4] [5] [7] [8], and other sensitive data [1] [2] [4] [5], effectively compromising all confidential information [7]. The browser syncjacking attack highlights significant vulnerabilities in the management of remote profiles and browsers [3] [4] [5] [7] [8], as attackers can create managed accounts without identity verification [1] [3] [4] [7], making it difficult to trace the source of the attacks [8].
This attack technique underscores a critical blind spot in enterprise security, as organizations typically lack visibility into the browser extensions their employees install [6] [10]. The attack operates with minimal permissions and user interaction [1] [3] [4] [5] [7] [8], relying on subtle social engineering tactics that make it challenging for employees to detect [7]. Traditional security tools are inadequate against these sophisticated browser-based attacks [4] [5] [6] [7] [8] [9] [10], which exploit seemingly benign extensions to facilitate complete device takeovers while evading detection by conventional security measures [6]. The need for enhanced visibility and control at the browser level is critical [9], as organizations risk leaving themselves vulnerable to such attacks without adequate defenses [9]. To address these challenges, organizations are encouraged to implement browser-level detection and response solutions, as advanced threats necessitate a more proactive approach to monitoring and managing browser extension activity. Users should also avoid installing unnecessary Chrome extensions and scrutinize new extensions and their developers for suspicious signs to mitigate the risk of such attacks.
Conclusion
The emergence of browser syncjacking highlights a significant vulnerability in enterprise security, emphasizing the need for improved visibility and control over browser extensions. Organizations must adopt proactive measures, such as browser-level detection and response solutions [3] [4], to counteract these sophisticated threats. Additionally, users should exercise caution by avoiding unnecessary extensions and thoroughly vetting new ones. As browser-based attacks continue to evolve, staying vigilant and implementing robust security practices will be crucial in mitigating risks and safeguarding sensitive information.
References
[1] https://web3wire.org/web3/squarex-discloses-browser-syncjacking-a-new-attack-technique-that-provides-full-browser-and-device-control-putting-millions-at-risk/
[2] https://www.tomsguide.com/computing/online-security/billions-of-chrome-users-at-risk-from-new-browser-hijacking-syncjacking-attack-how-to-stay-safe
[3] https://www.nextbigfuture.com/2025/01/squarex-discloses-browser-syncjacking-a-new-attack-technique-that-provides-full-browser-and-device-control-putting-millions-at-risk.html
[4] https://techbullion.com/squarex-discloses-browser-syncjacking-a-stealthy-new-attack-that-hijacks-devices-via-malicious-browser-extensions/
[5] https://www.cio.com/article/3813315/squarex-discloses-browser-syncjacking-a-new-attack-technique-that-provides-full-browser-and-device-control-putting-millions-at-risk.html
[6] https://www.infosecurity-magazine.com/news/full-browser-device-takeover/
[7] https://hackread.com/squarex-browser-syncjacking-attack-browser-device-control/
[8] https://cybersecuritymarket.com/squarex-discloses-browser-syncjacking-a-new-attack-technique-that-provides-full-browser-and-device-control-putting-millions-at-risk/
[9] https://www.techzine.eu/news/security/128255/taking-over-browsers-via-syncjacking-what-is-it/
[10] https://ciso2ciso.com/syncjacking-attack-enables-full-browser-and-device-takeover-source-www-infosecurity-magazine-com/
