Canvas fingerprinting is a sophisticated tracking technique that websites use to identify and track visitors without relying on cookies. It works by using the HTML5 canvas element to make the visitor's browser draw a hidden image. The unique characteristics of how different devices render this image create a distinctive "fingerprint" that can identify users across websites.
How canvas fingerprinting works
When you visit a website using canvas fingerprinting, it runs JavaScript code in your browser. This code asks your browser to draw an invisible image with specific text and shapes. The way your device renders this image depends on your hardware, operating system, and browser settings.
The resulting image is converted into a hash - a unique string of numbers and letters. This becomes your device's fingerprint, which websites can use to recognize you.
Why advertisers should care about canvas fingerprinting
Canvas fingerprinting can be used by both legitimate advertisers and fraudsters. For advertisers, it helps track ad performance and prevent duplicate counting. But fraudsters use it to make bot traffic appear more human-like.
Bad actors can use canvas fingerprinting to create convincing fake profiles that mimic real users. This makes it harder to detect click fraud and invalid traffic.
Protecting against fingerprinting abuse
There are several ways to defend against malicious use of canvas fingerprinting:
- Use anti-fraud solutions that can detect suspicious fingerprinting patterns
- Monitor traffic sources for unusual fingerprint distributions
- Look for multiple clicks coming from identical fingerprints
- Consider implementing rate limiting based on fingerprints
The future of canvas fingerprinting
As privacy concerns grow, some browsers are starting to block canvas fingerprinting. However, fraudsters continue developing new techniques to generate fake fingerprints. This creates an ongoing challenge for advertisers trying to protect their campaigns from invalid traffic.
The key is staying informed about both legitimate and malicious uses of this technology. This helps advertisers better protect their campaigns while maintaining effective tracking.
See also: fingerprinting
