Blog | G5 Cyber Security

Browser Antivirus: Benefits & How It Works

G5 Cyber Security

TL;DR

Injecting antivirus directly into your browser adds an extra layer of security against threats like phishing, malware downloads, and malicious scripts. It’s faster than traditional antivirus because it scans files *before* they are saved or executed. This guide explains the benefits and how it works.

What is Browser Antivirus?

Traditional antivirus software sits outside your browser, scanning files after you download them. Browser antivirus (also called in-browser protection) runs within the browser itself. It intercepts web traffic and scans content in real-time as it’s being downloaded or executed.

Benefits of Injecting Antivirus Inside Your Browser

  1. Faster Response Time: Because scanning happens before files are saved, threats are detected and blocked quicker. This reduces the risk of infection significantly.
  2. Protection Against Zero-Day Threats: Some browser antivirus solutions use heuristics (behavioural analysis) to identify new or unknown malware that signature-based antivirus might miss.
  3. Phishing Protection: Browser extensions can analyse websites in real-time, identifying and blocking phishing attempts before you enter any sensitive information.
  4. Malicious Script Blocking: It prevents the execution of harmful JavaScript code injected into web pages.
  5. Download Scanning: Scans downloaded files immediately, preventing them from being saved if they are malicious.
  6. Reduced System Load: Offloads some scanning tasks from your main antivirus software, potentially improving system performance.

How Does It Work?

Browser antivirus typically works by injecting a small piece of code (an extension or module) into the browser’s core processes. This code then performs several key functions:

  1. Web Traffic Interception: The injected code intercepts HTTP(S) requests made by the browser.
  2. URL Filtering: Checks URLs against known blacklists of malicious websites.
  3. Content Scanning: Scans downloaded files and web page content for malware signatures and suspicious behaviour.
  4. Sandbox Analysis: Some advanced solutions run potentially dangerous code in a sandbox environment to observe its behaviour without affecting your system.
  5. Real-time Reporting: Sends information about detected threats back to the antivirus vendor for analysis and updates.

Implementing Browser Antivirus

You usually don’t ‘inject’ code directly yourself. Instead, you install a browser extension provided by an antivirus vendor.

  1. Choose a Reputable Provider: Select a well-known and trusted antivirus company (e.g., Bitdefender, Norton, McAfee).
  2. Install the Extension: Visit your chosen provider’s website and download the browser extension for Chrome, Firefox, Edge or Safari.
  3. Enable the Extension: Follow the on-screen instructions to enable the extension within your browser settings. You may need to grant permissions for it to access web traffic data.
  4. Keep It Updated: Ensure the extension is automatically updated to receive the latest threat definitions and security improvements. Most extensions update automatically, but check the settings to confirm.

Example Extension Installation (Chrome)

Here’s how to install a browser extension in Chrome:

  1. Open the Chrome Web Store.
  2. Search for your chosen antivirus extension.
  3. Click “Add to Chrome”.
  4. Confirm the permissions requested by the extension.

Technical Considerations

Browser antivirus extensions typically use JavaScript APIs to interact with the browser’s core functionality. They may also communicate with a remote server for threat intelligence updates.

// Example JavaScript code snippet (simplified)
function interceptRequest(request) {
  const url = request.url;
  if (isMaliciousURL(url)) {
    cancelRequest(request); // Block the request
  } else {
    continueRequest(request); // Allow the request
  }
}

Limitations

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