Website Scripts & Browser Security Breaches

TL;DR

Yes, malicious scripts have broken out of browser sandboxes and accessed files on users’ computers. This is rare but possible, usually involving a combination of vulnerabilities in the browser itself, extensions, or operating system components. Modern browsers have strong security measures, but staying updated and being careful about what you click are vital.

Understanding Browser Sandboxing

Browsers use ‘sandboxing’ to isolate websites from your computer. Think of it like a secure container. Scripts running on a website should only be able to access things within that container – cookies, local storage, etc. They shouldn’t be able to touch your files directly.

How Breaches Happen: Common Methods

1. Browser Vulnerabilities: The browser software itself can have flaws. These are often found and patched quickly, but there’s a window of opportunity for attackers.
   • Example: A bug in how JavaScript handles certain file types could allow an attacker to read files outside the sandbox.
2. Extension Vulnerabilities: Browser extensions have more access than regular websites. A compromised or malicious extension is a significant risk.
   • Example: An extension claiming to block ads might secretly steal data from your browser history and local files.
3. Operating System Exploits: Sometimes, the attack doesn’t directly break the sandbox but exploits weaknesses in your operating system (Windows, macOS, Linux) that the browser relies on.
   • Example: A flaw in how Windows handles file permissions could be used to access files even if the browser is sandboxed.
4. Cross-Site Scripting (XSS): While not a direct sandbox break, XSS can allow attackers to inject malicious scripts into trusted websites.
   • Example: A website allows user input without proper sanitisation. An attacker enters JavaScript code that steals cookies or redirects you to a phishing site.
5. Clickjacking & Social Engineering: Tricking users into clicking something they shouldn’t, which then triggers malicious actions.
   • Example: A hidden iframe on a website prompts you to grant permissions to access your webcam or microphone.

Notable Past Breaches

While specific details are often kept confidential, here are some examples of types of attacks that have occurred:

• CVE-2019-1367: A vulnerability in certain versions of Chrome allowed attackers to execute arbitrary code outside the sandbox.
• Extension Malware: Numerous cases of malicious browser extensions being used for data theft, ad fraud, and cryptocurrency mining.
• Exploits targeting PDF readers within browsers: Vulnerabilities in Adobe Acrobat Reader (often accessed through a browser) have been exploited to install malware.

How to Protect Yourself

1. Keep Your Browser Updated: This is the most important step! Updates include security patches.
   • Chrome, Firefox, Safari, and Edge all update automatically, but check settings to ensure this is enabled.
2. Use a Reputable Antivirus/cyber security Software: A good antivirus program can detect and block malicious scripts and extensions.
3. Be Careful with Extensions: Only install extensions from trusted sources (official app stores). Check permissions before installing.
   • In Chrome, go to chrome://extensions to manage your extensions.
4. Enable Browser Security Features: Most browsers have built-in security features like phishing protection and malware blocking.
   • Chrome’s Enhanced Safe Browsing is a good example.
5. Be Wary of Suspicious Websites: Avoid websites that look untrustworthy or ask for excessive permissions.
6. Use a Strong Password Manager: This helps protect against keyloggers and phishing attacks.
7. Regularly Scan Your Computer: Use your antivirus software to scan for malware.

Checking Permissions (Example – Chrome)

You can review the permissions granted to extensions in Chrome:

chrome://extensions

Look at what each extension is allowed to do – access your browsing history, read and change data on websites, etc. Revoke unnecessary permissions.