How to Detect Privacy Leaks in Browser Extensions

The currently mainstream browsers are Chrome, Edge, or Firefox, and using these browsers may encounter some issues with plugins.

Many seemingly ordinary small plugins may be collecting browsing history, uploading clipboard contents, or even secretly establishing browser fingerprints.

The problem is that most people don't know how to check plugins. Next, I will explain in detail how to detect and protect against privacy leaks from browser plugins.

1. WhyBrowser extensionDo we need regular "check-ups"?

In the browser ecosystem, plugins are the components that are most easily overlooked yet carry the greatest privacy risks. Many people believe that plugins only affect performance, but in reality, a plugin with excessive permissions can achieve far more than you might imagine.

1. Plugin permissions are highly sensitive.

• "Read and change all data you access on the website"

• "Visit your download history"

• "Read clipboard content"

Many plugins request permissions at installation that are far greater than what their actual functionality requires, which gives them the opportunity to monitor user behavior.

2. The source of the plugin is complex.

Some plugins come from individual developers, unknown teams, or even repackaged versions, and the possibility of malicious code in between cannot be ignored.

3. The automatic update of plugins cannot be completely controlled.

Even if the plugin is safe when you install it, subsequent updates may add new tracking modules. You might not even notice any changes.

Therefore, it is essential to conduct periodic privacy risk assessments on plugins. Whether you are an ordinary user, a web development engineer, or a corporate security manager, maintaining a transparent and controllable browser environment is crucial for privacy.

2. CommonBrowser extension privacy leakagemeans

To understand how to detect risks, one must first comprehend the ways in which plugins typically leak privacy. Here are a few actual examples, not theoretical conjectures.

1. Background script listens to browsing behavior

Plugins can run scripts in the background, monitor the URLs you open, the time you spend on webpages, and even determine your usage habits. This data is sufficient to create user profiles.

2. Send hidden requests externally (most common)

For example, requesting an interface from a third-party domain, which contains your IP, browsing history, plugin environment data, etc.

Many malicious plugins use this method to "wash data."

3. Injecting scripts to read page content

Some plugins may inject JS to read the DOM, which means they might access your input, including search history and even password fields (if security measures are insufficient).

4. Browser Fingerprint Collection

Some plugins secretly collect browser fingerprints, such as Canvas fingerprints, WebGL parameters, media device IDs, etc.

This type of tracking is very difficult for ordinary users to detect, so it is essential to use browser fingerprint detection tools for inspection.

After understanding these methods, you will realize why a single "permission list" is far from enough and that more dimensional detection methods are needed.

3. A practical set ofBrowser plugin detection process(From novice to advanced)

Step 1: Check plugin permissions (basic but very important)

Go to the browser extension page, and review the permissions of each plugin one by one to determine if they are reasonable based on their functions.

For example:

• A PDF viewer plugin needs "access to all website data"? That's unreasonable.

• A screenshot plugin requests "read clipboard"? That's understandable.

This part is basic, but it can filter out 30% of suspicious plugins.

Step 2: Monitor Plugin Network Requests (Essential for Advanced Users)

You can use the following method:

• Browser Developer Tools → Network

• Fiddler

• Charles Proxy

• Wireshark

Key observation:

• Are there frequent requests for unknown domain names?

• Does the request content contain your URL, cookies, or other browsing data?

• Does the plugin ID appear in the request path?

If a plugin frequently connects to the internet even when you are not using it, it can generally be judged to have suspicious behavior.

Step 3: Browser Fingerprint Detection Comparison

Fingerprint collection is one of the hardest types of privacy breaches to detect and requires specialized detection.

The testing method is very simple:

1. Close all plugins → Test fingerprint

2. Enable the target plugin → Test again

3. Observe whether there are changes in two fingerprint IDs, Canvas rendering, WebGL parameters, etc.

If the change is significant, it indicates that the plugin is involved in tracking behavior.

Many browser fingerprint detection platforms provide detailed comparisons, which are very useful.

Step 4: Use the detection tool — ToDetect (recommended)

If you don't want to manually check permissions, review code, or capture packets, the easiest method is to use a one-click scanning platform like the ToDetect tool.

The features it offers include:

• Plug-in Permission Compliance Testing

• Plugin code analysis (including sensitive API calls)

• External Link Behavior Monitoring

• Browser Fingerprint Change Detection

• Privacy Risk Score

The advantage of ToDetect is that the detection results are clear and easy to understand, allowing ordinary users to easily grasp the risk points instead of being overwhelmed with a pile of technical jargon.

Especially suitable for:

• Want to quickly assess the security of a plugin.

• Companies need to audit employees' browser environments.

• Users who don't understand technology but want to protect their privacy.

It can be said to be the easiest type among the current browser plugin detection tools.

Summary of suggestions: The fewer plugins, the better; the earlier the protection, the better.

Do not install unused plugins, and try to use ToDetect or similar tools to check plugins from unknown sources. Conduct a monthly health check of browser plugins in conjunction with fingerprint detection tools to monitor changes in the browser environment.

In addition, high-privilege plugins must be重点排查, the browser is already your "data entry point," protecting it is more important than installing many antivirus programs.