Chrome Extensions Security Threats: Risk Analysis

Introduction

Browser extensions are tiny apps with big power. They can read pages, modify content, copy clipboard data, and call external APIs. That power is useful for productivity, yet it also attracts attackers. In the last year, researchers and newsrooms documented malicious or compromised Chrome extensions that tracked users, took screenshots of every visited page, or quietly redirected traffic for fraud. Many of these add-ons looked legitimate, had good reviews, and even appeared in the official Web Store. This guide explains how the threat works, what has changed with Chrome’s Manifest V3, and how organizations can reduce risk with a simple, enforceable policy. We use recent incidents and official sources, and we finish with a practical checklist that security and IT teams can apply today.

Chrome extensions security threats are risks that arise when extensions misuse or overuse permissions, receive malicious updates, or get hijacked to exfiltrate user data and manipulate web sessions at scale.

Power vs Risk

TLDR, Chrome extensions security threats by the numbers

• 1.7 million Chrome users installed malicious extensions that tracked activity, altered results, and redirected traffic. Most appeared useful and well reviewed. BleepingComputer
• The broader 2025 campaigns spanned 18 extensions across Chrome and Edge and impacted about 2.3 million users in total. Malwarebytes
• Attackers used developer account takeovers and phishing to push malicious updates at scale, forcing users to remove extensions manually even after takedowns. Reuters
• Researchers uncovered 131 rebranded clones abusing WhatsApp Web to spam users, a classic clone and rebrand pattern. The Hacker News
• A popular VPN add-on, FreeVPN.One, was caught screenshotting every page visited and exfiltrating data, despite a Featured badge in the store.

Fast facts table

What to do in 60 seconds

1. Open chrome://extensions, remove anything you do not recognize, then toggle Developer mode and review each extension’s site access and permissions.
2. Audit for wildcard host access and tabs plus scripting combos, remove if not essential.
3. For teams, switch to an allowlist policy, re-review on every version change, and monitor outbound domains from extension processes.

How Chrome extensions become dangerous

1) Malicious updates after trust is earned

Attackers publish a useful tool, gather installs and reviews, then push a new version that adds tracking or data theft. Multiple reports in 2025 described extensions with millions of installs that later collected browsing activity or altered search results.

2) Developer account takeover

Phishing or OAuth abuse can give attackers publishing access. Once inside, they ship a malicious update to a trusted user base. A January 2025 analysis detailed a phish that spoofed Chrome Web Store policy notices to trick maintainers, which led to compromise and harmful releases. Reuters also reported a broader campaign against developer accounts.

3) Clone and rebrand operations

Threat actors copy a legitimate extension, change branding, and flood the store with look-alikes that automate spam or harvest data. Researchers recently exposed 131 rebranded clones that targeted WhatsApp Web users.

4) Permission overreach

Wide permissions like tabs, scripting, or host-permission wildcards let an extension read and alter content across many sites. A popular VPN add-on was found capturing screenshots of every visited page and shipping them to a remote server.

5) Store policy gaps and enforcement lag

Google updates store policies and removes known bad items, but investigators still find waves of spammy or borderline extensions that stay live for months, which increases exposure windows.

Google Chrome Extensions Real incidents, from 2024 to 2025

• 1.7 million installs, tracking and redirects. Almost a dozen malicious extensions on the official store tracked users and redirected to risky sites, despite providing the advertised feature. BleepingComputer
• Millions exposed to spyware behavior. A campaign with 18 extensions across Chrome and Edge monitored user behavior at scale, some with verification badges. Malwarebytes
• Developer compromises, mass impact. Newsrooms and researchers tied multiple hijacks to phishing that targeted maintainers. Users had to manually remove extensions, even after store takedowns. Reuters
• WhatsApp Web spam automation. 131 clones of a WhatsApp automation tool spammed users in Brazil, a classic copycat and rebrand tactic. The Hacker News
• Screenshots of every page. FreeVPN.One allegedly captured screenshots of all visited pages and transmitted them off device, despite being labeled Featured in the store.

Chrome~Update

Manifest V3, what actually changed for security

Manifest V3 replaces long-running background pages with event-driven service workers, and moves network blocking to declarativeNetRequest. The goal is fewer always-on scripts and tighter control over filtering logic. This is a step up for privacy and performance, and it limits some abuse patterns. It does not eliminate risky permissions, social engineering of developers, or post-install malicious updates. Users also saw popular MV2 extensions disabled as Google advanced the migration. Security improved, yet organizations still need policy and monitoring.

Chrome Web Store policies in 2025, and why they matter

Google tightened several Web Store rules in 2025, including stricter affiliate ad policies and ongoing policy refreshes. Enforcement promises removal for violations, which raises the bar for spammy monetization in extensions. These steps help, but they are not a substitute for enterprise controls. Treat store vetting as a useful filter, not a guarantee

Threat model, what extensions can access

• Page content on allowed hosts, including forms and tokens in DOM.
• Clipboard, downloads, and storage APIs.
• Cross-site visibility through tabs and scripting APIs.
• External calls to attacker servers after an update.
• Social engineering prompts that request more permissions later.

Recent research shows determined attackers can still publish and run malicious code in official stores, which validates a defense-in-depth approach.

The enterprise playbook, policy, vetting, and monitoring

1) Set an allowlist policy

• Permit only approved extensions based on business need.
• Block host-permission wildcards unless justified.
• Re-review at each version change.
• Store an internal record of who requested it, why, and which permissions it uses.

2) Use a structured vetting checklist

Assess before approval.

Function and scope

• Does the feature require requested permissions, or is it overreaching?
• Does it run on all sites or specific domains only?

Publisher trust

• Is the developer verified and active elsewhere, like GitHub or a company site?
• Are permissions stable across versions or creeping up?

Data behavior

• Does the privacy policy mention data destinations, retention, and processing purpose?
• Does the extension send telemetry or screenshots to external servers?

Operational signals

• Frequency of updates, sudden spikes in installs, and review anomalies.
• Whether it is a complete clone of another tool.

Use the checklist with recent examples in mind. Even Featured or verified items have gone wrong in practice.

3) Monitor for drift and malicious updates

• Subscribe to version change alerts for approved extensions.
• Re-scan manifest and permissions on each update.
• If an extension changes publisher or adds network endpoints, quarantine it and review.

4) Browser configuration

• Disable installing from outside the store.
• Enforce enterprise allowlist via policy.
• Lock down extension access to sensitive internal domains with site isolation and SSO device posture checks.

5) Detection and response

• Browser telemetry, look for unusual chrome.storage writes, new host permissions, or mass content scripts.
• Network telemetry, flag new domains contacted by extension processes.
• User education, warn about permission prompts after an update, and how to report suspicious behavior.

Practical checklist, approve or deny in minutes

1. Business need documented with the requester and use case.
2. Publisher validated with a known entity and consistent identity.
3. Permissions reviewed for scope and least privilege.
4. Network destinations audited for data egress risk.
5. Privacy policy checked for collection, retention, and third parties.
6. Version history reviewed for stability and permission creep.
7. Internal sandbox test on non-prod accounts before broad rollout.
8. Monitoring configured for updates and outbound calls.
9. User instructions provided, including how to report issues.
10. Scheduled re-review every 90 days or on any major update.

Case study patterns to watch

• Post-install switcheroo. Clean first release, then stealthy update that adds tracking or redirect logic. Seen across multiple 2025 incidents. BleepingComputer
• Developer phishing. OAuth consent abuse or fake policy emails used to seize publishing controls. Pulsedive Blog
• Clone armies. Dozens to hundreds of rebrands that automate abuse on a popular site. The Hacker News
• Feature camouflage. A VPN or productivity addon that secretly captures screenshots or keystrokes.

What Manifest V3 does not fix by itself

• Human factors, developer account security, and social engineering.
• Excessive permissions approved by users without scrutiny.
• External server abuse after an update.
• Clone and rebrand campaigns that ride normal store workflows.

MV3 reduces some always-on behaviors and makes blocking more declarative, which is good. Organizations still need policy control and telemetry. Chrome for Developers

Implementation guide for IT and security teams

Phase 1, inventory and freeze

• Export current extensions across the fleet.
• Freeze approvals except for urgent requests.
• Remove anything with wildcard host access that lacks a written exception.

Phase 2, review and enforce

• Apply the checklist.
• Move to allowlist enforcement in Chrome enterprise settings.
• Document owners for each extension and set update monitoring.

Phase 3, monitor and educate

• Add alerts for permission changes and new outbound endpoints.
• Publish a 1-page guide that shows examples of malicious prompts.
• Run a quarterly purge of unused extensions.

Conclusion

Chrome extensions increase productivity, yet they introduce serious security threats when permissions are broad or when attackers hijack developer accounts. Manifest V3 improves privacy and performance, but it is not a silver bullet. The reliable approach is policy control, structured vetting, and continuous monitoring. Use the checklist and implementation plan above, and you will reduce risk quickly while keeping the tools your teams need

FAQs

Are Chrome extensions safe in 2025?
Safer than years past, but not safe by default. Treat store vetting as a starting filter, then apply an organizational allowlist and monitoring.

Does Manifest V3 stop malicious extensions?
It reduces certain abuse paths and long-running scripts. It does not stop permission abuse, developer account hijacks, or clone campaigns.

What permissions should I consider red flags?
Wildcards for host permissions, full tabs access coupled with scripting, and clipboard or download access without a clear reason.

How do I know if an extension turned malicious after install?
Watch for permission changes, new outbound domains, or behavior like pop-up redirects and injected search results. Monitor updates and remove on suspicion, then scan endpoints.

If the store removes an extension, am I covered?
Not always. Users may need to manually remove it, and endpoints might still hold artifacts. Follow removal instructions and run a malware scan.

What is the fastest path to a safe extension program?
Adopt allowlisting, apply the checklist, and enforce re-review at each version change. Start with a 90-day refresh cycle.