The Hidden Risks of Browser Extensions: How Add-Ons Can Compromise Your Security

Executive Summary

Browser extensions have become essential tools for enhancing our online experience, adding functionality and customization options to our web browsers. From ad blockers and grammar checkers to password managers and productivity tools, these small software add-ons offer significant convenience to users. However, this convenience comes with substantial hidden security and privacy risks that many users fail to recognize.

Recent research reveals alarming statistics from LayerX’s 2025 Enterprise Browser Extension Security Report. Up to 53% of extensions installed in enterprise environments have “high” or “critical” risk permissions, allowing access to sensitive data like cookies, passwords, browsing history, and webpage contents. Even more concerning, 99% of enterprise users have browser extensions installed, with more than half running over ten extensions simultaneously, creating a vast attack surface for malicious actors. These extensions can silently harvest personal data, track online activity, and even hijack accounts.

The risks extend beyond overtly malicious extensions to include legitimate but poorly secured ones that can be compromised or taken over by attackers. This white paper explores these hidden dangers, examines real-world attack scenarios, and provides practical recommendations for maintaining a secure browsing experience while benefiting from the functionality that browser extensions provide.

Understanding Browser Extensions

What Browser Extensions Are and How They Enhance Functionality

Browser extensions are small software modules that extend the capabilities of web browsers like Chrome, Firefox, Edge, and Safari. They integrate directly with browsers to provide additional features beyond the browser’s core functionality. Extensions can modify web content, add new browser features, or provide services that enhance user experience.

Common types of browser extensions include:

• Ad blockers Filter out unwanted advertisements on websites
• Password managers Store and automatically fill in login credentials
• Grammar and spell checkers Identify and correct writing errors in real-time
• Shopping assistants Find deals and apply discount codes automatically
• Security tools Verify website safety and block malicious content
• Productivity enhancers Add tools for task management, note-taking, and organization
• Social media integrations Enable easier sharing and interaction with social platforms

These extensions have become deeply embedded in users’ daily workflows. According to recent findings from LayerX’s 2025 report, nearly 99% of enterprise users have browser extensions installed, and over half have more than ten extensions running simultaneously. This widespread adoption illustrates how integral these tools have become to the modern browsing experience.

The Permissions Model: What Extensions Can Access and Control

Browser extensions operate on a permissions-based model that defines what browser resources and data they can access. When users install an extension, they grant it various permissions that determine its capabilities and access level.

Common permission types include:

• Tabs and navigation View open tabs and browsing history
• Cookies and storage Access and modify browser cookies and local storage
• Web requests Intercept, modify, or redirect network traffic
• Bookmarks and downloads View and manage bookmarks and downloads
• Clipboard Read and write clipboard data
• User data Access browsing history, form inputs, and saved passwords

What many users don’t realize is the extensive access these permissions can provide. For example, an extension with permission to “read and change all your data on the websites you visit” can not only see every website you visit but also capture any information you enter, including passwords, credit card details, and personal information.

Research from LayerX’s 2025 report shows that 53% of extensions installed in enterprise environments have “high” or “critical” risk permissions, creating significant vulnerabilities that users often fail to recognize. Many users grant these permissions without fully understanding the potential security implications, essentially giving extensions a backdoor to their sensitive data.

How Major Browsers (Chrome, Firefox, Edge) Manage Extensions

Different browsers use varying approaches to manage extension security, though all maintain some form of web store for distribution and basic security screening.

Google Chrome

• Uses a permission-based model with explicit user consent
• Implements Manifest V3, a newer extension framework designed to enhance security
• Offers extension sandboxing to limit potential damage
• Conducts automated scanning for malicious code before publication
• Recently enhanced security measures following multiple extension-based attacks

Mozilla Firefox

• Employs a permission model similar to Chrome
• Reviews extensions before they appear in the Firefox Add-ons store
• Offers a “Recommended Extensions” program for verified, high-quality add-ons
• Monitors extension behavior for suspicious activity
• Continues to support the Web Request API, which some security experts consider a potential vulnerability

Microsoft Edge

• Adopts Chrome’s extension model (being Chromium-based)
• Conducts independent reviews of extensions
• Offers extensions from both the Microsoft Store and Chrome Web Store
• Implements additional security measures such as Smart Screen protection
• Recently enhanced monitoring for malicious extension behavior

Despite these protections, security researchers consistently find ways that malicious extensions can bypass screening processes. Recent incidents have shown that even with these safeguards in place, dangerous extensions have appeared in official stores, sometimes accumulating hundreds of thousands of downloads before detection.

As documented by Carnegie Mellon University’s Information Security Office, in December 2024, over 30 malicious browser extensions were discovered in the Chrome Web Store, with 20 stealing credentials and session cookies through injected malicious code. The extensions’ developers had their Chrome Web Store credentials compromised through phishing attacks, allowing attackers to publish modified versions containing malicious code.

How Malicious Browser Extensions Work

Types of Malicious Extensions

Malicious browser extensions come in several forms, each presenting unique threats to users.

Adware and Spyware-Infested Extensions These extensions appear legitimate but contain hidden code that serves unwanted advertisements or monitors user activity. According to research from Zimperium, adware and spyware account for the majority of malicious extension families, with “11 out of the top 15 discovered falling into one of those two” categories. These extensions may flood users with pop-ups, redirect searches to sponsored sites, or replace legitimate ads with ones that profit the attackers. They often collect browsing data to target ads more effectively, creating both privacy and security risks.

Data-Harvesting Extensions Posing as Legitimate Tools These extensions provide the advertised functionality while secretly collecting sensitive user data. For example, a screenshot tool might legitimately capture web pages while simultaneously harvesting passwords, form inputs, or financial information.

Extensions Injecting Malicious Scripts or Redirecting Traffic These extensions modify web content to insert malicious code, redirect users to phishing sites, or manipulate web traffic. They may appear harmless until they receive remote commands to download and execute malicious payloads. The ChromeLoader malware, documented by multiple security researchers in 2023-2024, manipulated search results and redirected users to phishing sites, fake prize giveaways, unwanted software, and adult content, all while making itself difficult to remove by creating persistent scripts and scheduled tasks.

Case Studies of Real-World Browser Extension Attacks

Several major browser extension attacks have demonstrated the real-world impact of these threats.

The MEGA.NZ Chrome Extension Compromise (2018) One of the most notable cases occurred when the MEGA.NZ Chrome extension was compromised and began leaking usernames, passwords, and cryptocurrency private keys of its 1.7 million users to a hacker-controlled server. The attack lasted for four hours before the extension was updated, but by then, substantial damage had already occurred. This incident highlighted how quickly and effectively attackers could exploit a trusted extension, as documented by Jscrambler.

The Great Suspender Takeover (2021) This popular extension, used by millions to manage memory usage in Chrome, was sold to an unknown entity that added malicious tracking and data exfiltration code. Google eventually removed it from the Chrome Web Store, but not before many users had their data compromised. This case demonstrated the risks of extension ownership changes and the potential for previously trusted tools to become threats, as outlined by Spin.AI.

The Cyberhaven Attack (December 2024) In late 2024, security researchers discovered over 30 malicious extensions in the Chrome Web Store. The attack was uncovered when Cyberhaven, a data loss prevention company, noticed its Chrome extension had been updated with code that stole sensitive data. Further analysis revealed the extension had been modified to download payloads capable of exfiltrating browser cookies and authentication credentials. In total, at least 33 extensions were compromised, with some like “Reader Mode” potentially compromised as early as April 2023, according to Field Effect.

ChatGPT Extensions Breach (2023) Researchers discovered a malicious version of “ChatGPT for Google” on the Chrome Web Store that functioned like the legitimate extension but included additional code designed to steal Facebook session cookies. The attackers used these stolen cookies to hijack Facebook accounts, which were then used for malicious purposes. Another similar extension called “Quick access to Chat GPT” also performed its advertised function while secretly collecting user data, as reported by Kaspersky.

How Attackers Use Social Engineering to Trick Users

Attackers employ sophisticated social engineering tactics to convince users to install malicious extensions.

Impersonating Popular Extensions Malicious actors create extensions with names and interfaces that closely resemble legitimate, popular extensions. They may use slight variations in spelling or logo design that are easy to miss. According to research from Tom’s Guide, hackers have created lookalike sites impersonating popular software and services like YouTube, VLC media player, and Steam to distribute malicious extensions.

Exploiting Trending Topics Attackers quickly capitalize on popular trends and emerging technologies. For instance, when ChatGPT gained popularity, multiple malicious extensions appeared offering enhanced access to the AI tool while secretly stealing user data. In 2023, researchers identified two malicious extensions in the Google Chrome Web Store claiming to enhance ChatGPT functionality, both designed to steal user credentials.

Using Fake Reviews and Download Numbers Attackers artificially inflate ratings and download counts to create a false sense of legitimacy and trust. They use bot networks to post positive reviews and increase installation numbers, making the extension appear more trustworthy than it actually is.

Leveraging Limited-Time Offers Some attackers create a sense of urgency with “limited-time” features or special offers, pressuring users to install without proper consideration of security implications. These tactics reduce the likelihood that users will research the extension before installation.

Exploiting Trust in Official Stores Many users implicitly trust extensions from official web stores, assuming they’ve been properly vetted. Attackers exploit this trust by finding ways to bypass security screening processes or compromising legitimate developer accounts, as documented by Carnegie Mellon University’s Information Security Office in 2025.

Security Risks from Legitimate but Vulnerable Extensions

How Poorly Coded Extensions Can Expose Users to Security Flaws

Even extensions created with legitimate intentions can introduce significant security vulnerabilities due to poor coding practices. These flaws can be exploited by attackers to gain unauthorized access to sensitive information or execute malicious code.

Inadequate Data Validation Extensions that fail to properly validate input can be vulnerable to injection attacks. For example, an extension that doesn’t sanitize user input or website content before processing it could allow attackers to inject malicious scripts that execute within the extension’s privileged context.

Insecure Communication Extensions that don’t use secure communication protocols (HTTPS) when transferring data leave users vulnerable to man-in-the-middle attacks, where attackers can intercept and modify the exchanged information. Security researchers have identified numerous extensions with this vulnerability.

Excessive Permissions Even well-intentioned extensions often request more permissions than necessary for their functionality. This creates unnecessary risk, as any vulnerability in the extension could give attackers access to a broader range of sensitive user data. According to Dark Reading, a study by Spin.AI found that 51% of all installed extensions were high risk, with overly permissive access that could enable data capture and run malicious JavaScript.

Insufficient Authentication Extensions that handle sensitive data but implement weak authentication mechanisms can leave user information vulnerable to unauthorized access. Without proper authentication, attackers can potentially access private data stored or processed by the extension.

The Risk of Abandoned Extensions Being Taken Over by Attackers

Extensions that are no longer actively maintained present unique security risks.

Vulnerability to Emerging Threats Without regular updates, abandoned extensions don’t receive patches for newly discovered vulnerabilities in their code or the browser APIs they use. This leaves users exposed to emerging security threats that target these unpatched vulnerabilities.

Ownership Transfer Risks When developers abandon extensions with large user bases, they sometimes sell or transfer them to new owners. This transition can lead to security compromises if the new owner has malicious intent. The case of “The Great Suspender” illustrates this danger – the popular Chrome extension was sold to an unknown entity that subsequently inserted malicious tracking code, affecting millions of users before Google removed it from the Chrome Web Store in 2021, as documented by Spin.AI.

Lack of Security Monitoring Active developers typically monitor their extensions for unusual behavior or unauthorized modifications. Abandoned extensions lack this oversight, making it easier for attackers to compromise them without detection.

How Automatic Updates Can Introduce Vulnerabilities Without User Knowledge

The automatic update feature of browser extensions, while convenient, can become a significant security risk.

Supply Chain Attacks Attackers may target extension developers’ accounts or infrastructure to push malicious updates to legitimate extensions. In December 2024, researchers discovered that over 30 Chrome extensions had been compromised when attackers gained access to developer accounts through phishing attacks, allowing them to push updates containing code that stole credentials and session cookies, as documented by Carnegie Mellon University’s Information Security Office.

Delayed Detection Users rarely review the code changes in extension updates, meaning malicious modifications can operate undetected for extended periods. The “Reader Mode” extension, for example, may have been compromised as early as April 2023 but wasn’t identified until the broader campaign was discovered in December 2024.

Gradual Malicious Behavior Sophisticated attackers often introduce malicious functionality gradually through updates. Initial updates might only add dormant malicious code, while subsequent updates activate it, making the transition to malicious behavior less noticeable to users and security systems alike. The “Dormant Colors” campaign identified in 2023 involved 30 unique extensions that were initially legitimate but later injected with malicious code to harvest information, as reported by Panda Security.

Extension API Changes Browser updates that modify extension APIs can inadvertently create security vulnerabilities in extensions that haven’t been updated to accommodate these changes. This is particularly problematic for abandoned extensions that no longer receive compatibility updates.

Examples of Security Breaches Caused by Legitimate Extensions

Several notable security incidents have resulted from vulnerabilities in legitimate extensions.

DataSpii Incident (2019-2020) Security researchers discovered that several widely-used Chrome and Firefox extensions were silently harvesting browsing data from millions of users, exposing sensitive corporate information. These extensions had been legitimate tools that either changed ownership or were updated to include data collection functionality.

Cyberhaven Extension Compromise (2024) A data loss prevention company, Cyberhaven, discovered its own Chrome extension had been compromised when it was updated with code that included functionality to steal sensitive data from users. The extension, used by 400,000 customers, had been configured to download payloads capable of exfiltrating browser cookies and authentication credentials, as detailed by Field Effect.

SearchBlox Exploitation (2022) Two extensions named SearchBlox, ostensibly created to search for players on Roblox servers, were discovered in the Chrome Web Store with over 200,000 combined downloads. While providing their advertised functionality, they secretly contained malicious code that tracked user activity and manipulated search results, according to Kaspersky’s research.

The Privacy Implications of Browser Extensions

How Extensions Track User Activity and Collect Sensitive Data

Browser extensions often engage in extensive data collection that many users don’t fully understand.

Silent Data Collection Many extensions quietly gather browsing data, including URLs visited, search queries, and time spent on websites. A 2024 study from Georgia Tech revealed that thousands of browser extensions extract private user content from webpages without explicit consent or disclosure in their privacy policies. The researchers found that “none of them clearly described the automated user data collection in their privacy policy or web store description.”

Keystroke Logging Some extensions can record everything typed into forms, potentially capturing sensitive information like passwords, credit card details, and personal messages. Extensions with the ability to “read and change all your data on websites you visit” often have this capability, which creates significant security risks if the extension is compromised or intentionally malicious.

Content Scraping Extensions can scan the content of webpages you visit, extracting information like email addresses, social media profile details, or financial data. The LayerX 2025 report found that 53% of extensions installed in enterprise environments could access sensitive data including cookies, passwords, web page contents, and browsing information.

Form Data Interception Many extensions can view the data entered into web forms before it’s submitted, potentially accessing login credentials, payment information, and other sensitive details even when websites use secure connections.

Browser Fingerprinting Some extensions contribute to creating a unique digital fingerprint that can be used to track users across websites, even when traditional tracking methods like cookies are blocked.

Cross-Site Tracking Through Extensions

Extensions can enable sophisticated tracking across different websites.

Unified Identity Tracking Unlike website-specific cookies, extensions can maintain a persistent identity for users across all sites they visit, creating comprehensive browsing profiles that span the entire web.

Evading Privacy Protections While browsers increasingly block third-party cookies and other tracking mechanisms, extensions can bypass these protections by operating with elevated privileges within the browser environment.

Session Correlation Extensions can link separate browsing sessions together, negating the privacy benefits of clearing browser data or using private browsing modes. A compromised extension with appropriate permissions can access browsing data even in private/incognito windows.

Cross-Device Synchronization Extensions that sync data across devices can extend tracking beyond a single computer, creating a more comprehensive user profile that includes activity from multiple devices.

How Some Free Extensions Monetize Data Without User Consent

Many free extensions employ questionable data monetization practices.

Selling Browsing Histories Some extension developers generate revenue by collecting and selling detailed browsing histories to data brokers, advertising networks, or market research companies. This often happens without clear disclosure to users.

Injecting Affiliate Links Extensions may modify or insert affiliate links into websites, earning commissions on purchases without users’ knowledge. For example, the “Netflix Party” extension was found to track users’ digital footprints and inject affiliate links into appropriate pages, generating profit based on browsing history, according to Panda Security.

Replacing Advertisements Some extensions remove legitimate website ads and replace them with their own advertising networks, diverting revenue from website owners to extension developers while potentially exposing users to less secure ad content.

Behavioral Analysis for Targeted Advertising Extensions may analyze user behavior to build detailed profiles for targeted advertising, often with deeper insights than what’s available to normal websites due to their elevated access.

Premium Feature Upselling While not directly monetizing data, some extensions offer limited functionality for free while using collected data to personalize upselling strategies for premium features.

The Role of Third-Party Companies in Exploiting Extension Data

Multiple entities are involved in the extension data ecosystem.

Data Aggregators Companies purchase and compile user data from multiple extensions to create comprehensive profiles for advertising, market research, or other purposes. According to privacy researchers, this aggregated data can be particularly valuable because it provides cross-site visibility that individual websites cannot achieve.

Advertising Networks These companies use extension-collected data to deliver hyper-targeted advertisements across the web. Extensions with broad permissions can provide advertisers with insights that circumvent standard privacy protections.

Analytics Companies These firms process extension data to generate market insights, consumer trends, and competitive intelligence, often without users understanding their browsing behavior is contributing to such analysis.

Cybercriminal Markets In more malicious scenarios, data collected through extensions can be sold on underground markets for use in identity theft, account takeovers, or targeted phishing attacks. The 2025 Enterprise Browser Extension Security Report highlighted that 53% of enterprise users’ extensions can access sensitive data, creating significant risk for data theft and misuse.

Preventative Measures: How Users Can Stay Safe

Evaluating an Extension Before Installation

Before adding any extension to your browser, take these critical steps to assess its safety.

Check Permissions and User Reviews

• Review the specific permissions requested by the extension and question whether they align with its stated functionality. Be wary of extensions requesting excessive access.
• Read user reviews thoroughly, looking for consistent complaints about unexpected behavior, privacy concerns, or performance issues.
• Pay attention to review dates – a sudden influx of negative reviews may indicate a recent malicious update.

Research the Developer and Update History

• Investigate the developer’s reputation by searching for their name or organization online.
• Check whether they maintain other reputable extensions or software.
• Review the extension’s update history – frequent updates often indicate active maintenance and security patching.
• Be cautious if an extension has recently changed ownership, as this can sometimes precede the introduction of malicious features.

According to the 2025 Enterprise Browser Extension Security Report, 54% of extension publishers are unknown and only identified via Gmail accounts, with 79% having published only one extension. This lack of established reputation makes verifying trustworthiness difficult.

Limiting the Number of Installed Extensions

Extension management is crucial for maintaining browser security.

• Regularly audit your installed extensions and remove those you no longer use or need.
• Follow the principle of least privilege – only install extensions that provide significant value to your browsing experience.
• Consider using different browsers for different purposes, keeping sensitive browsing (like banking) in a browser with minimal extensions.
• Be particularly cautious with extensions that handle sensitive data, such as password managers or financial tools.

LayerX’s research indicates that 52% of enterprise users have more than 10 extensions installed simultaneously, significantly increasing their attack surface and security risk.

Regularly Reviewing and Removing Unused or Suspicious Extensions

Implement a consistent extension maintenance routine.

• Schedule monthly reviews of all installed extensions.
• Remove extensions that haven’t been used recently or no longer serve a purpose.
• Check for unexpected behavior, such as increased browser resource usage, new pop-ups, or changes to your browsing experience.
• Monitor extension updates and review permission changes when they occur.
• If you notice suspicious activity after an extension update, consider removing it immediately and researching whether others have reported similar issues.

Research from Spin.AI discovered that 51% of all installed extensions posed high security risks and had the potential to cause extensive damage to organizations, emphasizing the importance of regular reviews.

Using Browser Security Settings to Restrict Extension Capabilities

Modern browsers offer controls to limit extension access.

• Use site-specific permissions to restrict which websites each extension can access.
• Enable enhanced protection modes offered by your browser, which can help detect and block malicious extensions.
• Consider using extension “sandboxing” features that isolate extension operations from the rest of your browser.
• In enterprise environments, implement group policies that restrict which extensions can be installed.
• Configure your browser to require manual approval for extension updates rather than allowing automatic installation.

Microsoft’s Defender Vulnerability Management now includes browser extension assessment capabilities that provide visibility into installed extensions, helping security teams identify and manage potential risks.

Trusted Sources for Downloading Extensions

Always obtain extensions from official, vetted sources.

• Use only official browser web stores: Chrome Web Store, Mozilla Add-ons, or Microsoft Edge Add-ons.
• Be extremely cautious of extensions promoted through ads, pop-ups, or unsolicited recommendations.
• Verify that you’re on the legitimate store website before downloading any extension.
• Consider extensions from the browser’s “recommended” or “featured” sections, which typically undergo additional security review.
• For organizational use, explore enterprise extension deployment options that include additional security vetting.

Research has shown that extensions distributed outside official stores pose significantly higher risks. A 2024 report from Tom’s Guide noted that hackers frequently create lookalike sites impersonating popular software to distribute malicious extensions through unofficial channels.

The Role of Browser Developers and Cybersecurity Policies

How Browsers Like Chrome and OneStart Are Improving Extension Security

Leading browser developers are implementing increasingly robust security measures to protect users from malicious extensions.

Google Chrome’s Security Enhancements

• Implemented Manifest V3, a new extension framework that restricts access to sensitive APIs and limits what extensions can do without user interaction.
• Added runtime host permissions that allow users to grant site access to extensions on a case-by-case basis.
• Enhanced automated review processes for Chrome Web Store extensions, including code analysis and behavior monitoring.
• Introduced Enhanced Safe Browsing to detect and warn users about potentially harmful extensions.

OneStart’s Advanced Security Features: At OneStart, we’ve taken browser extension security to the next level by integrating essential productivity tools natively within our browser. This approach dramatically reduces the need for third-party extensions, minimizing the attack surface that malicious actors can exploit. Our built-in tools provide functionality that would otherwise require multiple external extensions, but with the security assurance of being developed and maintained by our dedicated security team.

Key OneStart security features include:

• Comprehensive extension vetting and safety rating system
• Real-time monitoring of extension behavior for suspicious activity
• Integrated privacy-first productivity tools that eliminate the need for third-party solutions
• Granular permission controls that limit extension access to sensitive data

Mozilla Firefox’s Approach

• Developed a recommended extensions program that highlights thoroughly reviewed, high-quality extensions.
• Implemented strict add-on signing requirements to prevent unauthorized modifications.
• Created a permissions-based system with clear user consent workflows.
• Established a rapid response team for extension-related security incidents.

The Effectiveness (and Limitations) of Browser Extension Stores’ Vetting Processes

While browser developers have improved their extension vetting processes, significant limitations remain.

Effectiveness of Current Vetting

• Automated scanning successfully catches many common types of malicious code and known threats.
• Human reviews supplement automated systems for featured or popular extensions.
• Reputation systems help identify trustworthy developers and flag suspicious new entries.
• Post-publication monitoring can detect extensions that exhibit malicious behavior after approval.

Persistent Limitations

• The sheer volume of extensions makes comprehensive review challenging. Recent findings indicate that among over 100,000 Chrome extensions available for download, it’s nearly impossible for Google to verify all of them effectively.
• Sophisticated obfuscation techniques can hide malicious code from automated scanners. Attackers increasingly use delayed activation of malicious features to evade detection during the review process.
• Limited resources for manual reviews mean many extensions receive primarily automated screening. According to the 2025 Enterprise Browser Extension Security Report, 54% of extension publishers are unknown and only identified via Gmail accounts, with 79% having published only one extension, making trust assessment extremely challenging. This lack of established reputation creates significant difficulties in verifying trustworthiness during the review process.
• Lag time between identifying malicious extensions and removing them from stores gives attackers a window of opportunity. The Cyberhaven extension incident in 2024 showed that a malicious extension was available in the Chrome store for 31 hours before detection.

Emerging Challenge: Supply Chain Attacks: A growing concern is the compromise of legitimate developer accounts. In late 2024, at least 33 Chrome extensions were found to be malicious after attackers compromised developer accounts using phishing attacks. This allowed them to publish malicious updates to previously legitimate extensions, bypassing normal security reviews.

Regulatory Efforts and Future Security Improvements in Extension Management

The regulatory landscape around browser extension security is evolving, with several promising developments:

Current Regulatory Framework

• Data protection regulations like GDPR and CCPA indirectly impact extension security by requiring clear disclosures about data collection.
• Browser-specific policies govern extension behavior, though these are set by browser developers rather than regulatory bodies.
• Industry standards organizations are developing best practices for extension security.

Emerging Regulatory Efforts

• Privacy-focused legislation increasingly addresses browser extensions specifically.
• Cybersecurity agencies in multiple countries have issued guidance on browser extension security risks.
• Consumer protection agencies have begun taking action against deceptive extension practices.

Future Security Improvements: Browser developers and security researchers are working on several promising advancements:

• Enhanced sandboxing technology to isolate extensions from sensitive browser data
• Artificial intelligence systems to better detect malicious extension behavior
• More granular permission systems giving users greater control
• Improved supply chain security to prevent developer account compromises
• Regular security audits for high-risk or widely-used extensions

At OneStart, we’re at the forefront of these efforts, integrating advanced security features into our browser while providing the productivity tools users need without requiring third-party extensions. Our approach centers on building security directly into the browser experience, significantly reducing the risks associated with external add-ons.

Conclusion and Recommendations

Summary of Key Risks and Takeaways

Browser extensions represent a significant and often underestimated security risk in today’s digital landscape. The research presented in this white paper highlights several critical concerns.

• Extensive Access Modern browser extensions can access sensitive data including passwords, browsing history, form inputs, and cookies. According to LayerX’s 2025 report, 53% of extensions in enterprise environments have high or critical risk permissions.
• Widespread Usage With 99% of enterprise users having browser extensions installed and 52% running more than ten extensions simultaneously, as reported by BleepingComputer, the attack surface is extensive and growing.
• Multiple Threat Vectors Threats come from overtly malicious extensions, legitimate extensions that become compromised, and abandoned extensions that become vulnerable to takeover. The 2024 discovery of 33 malicious Chrome extensions demonstrates how even trusted extensions can become attack vectors.
• Privacy Implications Beyond security concerns, many extensions track user activity across websites, collect sensitive data, and monetize this information without clear user consent or knowledge.
• Inadequate Vetting Despite improvements, app store review processes remain insufficient to catch all malicious extensions, particularly those using sophisticated obfuscation or delayed activation techniques.
• Low User Awareness Most users install extensions without thoroughly understanding their permission requirements or security implications, creating opportunities for attackers. critical risk permissions.
• Widespread Usage With 99% of enterprise users having browser extensions installed and 52% running more than ten extensions simultaneously, the attack surface is extensive and growing.
• Multiple Threat Vectors Threats come from overtly malicious extensions, legitimate extensions that become compromised, and abandoned extensions that become vulnerable to takeover. The 2024 discovery of 33 malicious Chrome extensions demonstrates how even trusted extensions can become attack vectors.
• Privacy Implications Beyond security concerns, many extensions track user activity across websites, collect sensitive data, and monetize this information without clear user consent or knowledge.
• Inadequate Vetting Despite improvements, app store review processes remain insufficient to catch all malicious extensions, particularly those using sophisticated obfuscation or delayed activation techniques.
• Low User Awareness Most users install extensions without thoroughly understanding their permission requirements or security implications, creating opportunities for attackers.

Best Practices for Individuals and Organizations to Mitigate Risks

Based on current research and security best practices, we recommend the following approaches to mitigate browser extension risks.

For Individuals

• Conduct a thorough audit of currently installed extensions and remove any that aren’t actively used or trusted.
• Before installing new extensions, carefully review permissions requested and question whether they align with the extension’s stated purpose.
• Research extension developers, checking their reputation and other published software.
• Limit extensions to those from trusted, well-established developers with positive reviews.
• Regularly review extension behavior for unexpected activities like increased resource usage or browser slowdowns.
• Consider using different browsers for sensitive activities (banking, healthcare) and general browsing.
• Enable any additional security features offered by your browser for extension management.

For Organizations

• Implement a formal browser extension policy that specifies allowed extensions and installation procedures.
• Use enterprise browser management tools to enforce extension restrictions and monitor usage.
• Consider tools like Microsoft Defender Vulnerability Management that provide visibility into installed browser extensions across the organization.
• Conduct security awareness training focused specifically on browser extension risks and safe practices.
• Regularly audit extensions installed across the organization, particularly those with access to sensitive corporate data.
• Create and maintain a whitelist of approved extensions that have undergone security review.
• Monitor for browser extension-related security incidents and vulnerabilities in security bulletins.

Final Thoughts on Balancing Convenience and Security When Using Browser Extensions

Browser extensions offer tremendous value in customizing and enhancing the web browsing experience, but this convenience must be balanced against security considerations. We recommend a thoughtful, risk-based approach.

• Adopt a Minimalist Approach Install only extensions that provide significant value and functionality you regularly use. Each additional extension increases your attack surface.
• Prioritize Native Browser Features Whenever possible, use built-in browser functionality instead of third-party extensions. Modern browsers increasingly incorporate features that once required extensions.
• Consider Security-First Browsers Browsers like OneStart that integrate essential productivity tools natively reduce the need for extensions while maintaining robust security.
• Apply Contextual Security Adjust your security practices based on the sensitivity of your activities. Banking and healthcare sites warrant stricter security measures than general browsing.
• Stay Informed Keep abreast of security news related to browser extensions, particularly those you use regularly.

The browser extension ecosystem continues to evolve, with both security measures and threats becoming more sophisticated. By staying vigilant and applying these recommended practices, users and organizations can enjoy the benefits of browser extensions while significantly reducing their security risks.

At OneStart, we’re committed to providing a secure browsing experience with built-in productivity tools that minimize reliance on potentially risky third-party extensions. Our integrated approach offers the functionality users need while maintaining the highest security standards, representing the future of safe, efficient web browsing.