Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

For many, the technical inner workings of web browsers remain a mystery. We use them daily to manage our finances, from online banking to investment platforms, generally trusting that these tools are secure. However, a recent change in the Chromium browser – the engine powering Google Chrome, Microsoft Edge, and many others – has introduced a new, subtle, and potentially significant security risk. This risk stems from an update to how the Math.tanh function is handled, and it allows websites to fingerprint your operating system with surprising accuracy. This article explains what’s happening, why it matters for your finances, and what steps you can take to protect yourself.

§What is Browser Fingerprinting and Why Does It Matter for Finance?

Browser fingerprinting is a technique websites use to identify and track you, even if you block cookies or use a VPN. Unlike cookies, which can be deleted, fingerprints are built from details about your browser and system configuration. These details include:

• User Agent: Information about your browser and OS.
• Installed Fonts: The list of fonts available on your system.
• Browser Plugins: Extensions and plugins you have installed.
• Canvas Rendering: How your browser renders images using the <canvas> element.
• WebRTC IP Address Leakage: Potentially revealing your real IP address even with a VPN.
• And now… Math.tanh results.

Traditionally, fingerprinting has been used for benign purposes like analytics and preventing fraud. However, it can also be used for more nefarious activities, including:

• Targeted Advertising: Serving you ads based on a detailed profile.
• Price Discrimination: Showing you different prices based on your perceived willingness to pay.
• Account Takeover: Identifying potential targets for account hacking.
• Financial Fraud: Identifying users who might be vulnerable to scams or have higher account balances. This is where the risk becomes particularly acute.

For the financial sector, the ability to uniquely identify a user, even without traditional tracking methods, is a goldmine for fraudsters. It allows them to build detailed profiles and tailor attacks more effectively.

§The Chromium 148 Update: What Changed with Math.tanh?

Math.tanh is a JavaScript function that calculates the hyperbolic tangent of a number. Until Chromium version 148, the result of Math.tanh was consistent across different operating systems. This meant that, while it could be used in fingerprinting, it wasn't a reliable differentiator.

However, Chromium 148 introduced a change in how Math.tanh is implemented. The underlying algorithms used to calculate the function now vary slightly depending on the operating system (Windows, macOS, Linux). These subtle differences, while seemingly insignificant, create a unique “fingerprint” for each OS.

[Image suggestion: Screenshot of Javascript code using Math.tanh with a caption: "A simple Javascript snippet demonstrating the Math.tanh function."] (

This means a website can now execute Math.tanh in your browser and, based on the result, accurately determine which operating system you are using. Combined with other fingerprinting techniques, this dramatically increases the accuracy and reliability of user identification.

§Why is This Specific Fingerprinting Method So Dangerous?

The Math.tanh fingerprinting method is particularly concerning for several reasons:

• It's Passive: The website doesn't need any user interaction. The fingerprint is collected simply by running the JavaScript code.
• It's Difficult to Detect: The calculation itself is harmless. It doesn’t raise any red flags like suspicious network activity or unauthorized data access.
• It’s Highly Accurate: The variations in results across operating systems are consistent enough to allow reliable identification.
• It Bypasses Traditional Protections: Traditional privacy measures like cookie blocking and VPNs do little to mitigate this type of fingerprinting. The fingerprint is derived from your browser environment, not from data stored in cookies.

For financial institutions, this means fraudsters can more easily identify targets using specific operating systems that might be associated with higher wealth or less security awareness. Imagine a scenario where a fraudulent website specifically targets Windows users with tailored phishing campaigns.

§How Does This Impact Your Financial Transactions?

§The potential impact on your financial transactions is significant:

• Increased Risk of Phishing Attacks: Fraudsters can identify users more effectively and launch targeted phishing campaigns.
• Account Takeover Attempts: Knowing your operating system can help attackers craft more convincing social engineering attacks to gain access to your accounts.
• Fraudulent Transactions: More accurate user identification facilitates fraudulent transactions and reduces the chances of detection.
• Profiling for Loan Applications/Credit Checks: While less direct, this information could potentially be used to build more detailed user profiles for assessing creditworthiness or loan applications, potentially leading to discriminatory practices.

Consider using a password manager like to generate strong, unique passwords for all your financial accounts.

§What Can You Do to Protect Yourself?

While completely eliminating the risk is challenging, there are several steps you can take to mitigate it:

• Use Privacy-Focused Browsers: Browsers like Brave and Tor Browser are designed with privacy in mind and include built-in features to resist fingerprinting.
• Browser Extensions: Consider using browser extensions specifically designed to combat fingerprinting. Privacy Badger and uBlock Origin (with the right filter lists) can help.
• VPN (Virtual Private Network): While a VPN won't directly prevent Math.tanh fingerprinting, it adds another layer of privacy and masks your IP address. Consider or .
• Regularly Update Your Browser: Keep your browser updated to the latest version, as updates often include security patches and privacy enhancements.
• Enable Browser Privacy Settings: Configure your browser’s privacy settings to maximize your protection. Disable unnecessary features and limit data collection.
• Use Anti-Fingerprinting Software: Some security software, such as , includes anti-fingerprinting capabilities.
• Be Vigilant: Be cautious about clicking on links or downloading files from unknown sources. Double-check website URLs and look for security indicators (HTTPS).
• Consider Virtual Machines: For high-security tasks like online banking or investing, consider using a virtual machine with a different operating system. This creates a further layer of isolation.
• Use Different Browsers for Different Tasks: Don't use your primary browser for all activities. Use a dedicated browser for sensitive tasks like financial transactions.

[Image suggestion: Graphic showing layers of security: VPN, Anti-virus, strong passwords, etc. with a caption: "Layered security is key to protecting your financial data."] (

§The Future of Browser Fingerprinting & Financial Security

The Chromium Math.tanh update is a stark reminder that browser fingerprinting is an evolving threat. As websites become more sophisticated in their tracking methods, it's crucial to stay informed and take proactive steps to protect your privacy and financial data.

The ongoing “arms race” between privacy advocates and tracking technologies will likely continue. We can expect to see:

• New Fingerprinting Techniques: Websites will continue to explore new ways to fingerprint users.
• Improved Anti-Fingerprinting Tools: Developers will respond with increasingly sophisticated anti-fingerprinting tools.
• Increased Regulatory Scrutiny: Governments may introduce regulations to limit the use of fingerprinting and protect user privacy.

It's vital to remain vigilant, adapt your security practices, and advocate for stronger privacy protections. The security of your financial data depends on it.

§Disclaimer

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