Security company Finjan has unveiled a browser plug-in which it claims can alert users to potentially malicious content hiding behind links to search results, ads and other selected web pages.

The firm's SecureBrowsing tool accesses each web link in its current form and scans the relevant pages in real time using Finjan's behavior-based analysis technology.

Each link is then marked with a safety rating of safe (green) or potentially malicious (red).

"SecureBrowsing analyses website code in real time to provide users with safety ratings of URLs before they visit the sites," said Yuval BenItzhak, chief technology officer at Finjan.

"This approach helps to prevent potentially malicious content from entering companies' networks or PCs.

"Website content changes continuously, and a URL that was safe yesterday might contain malicious code today."

Finjan explained that malicious attacks are frequently performed from short-lived web pages that appear and vanish within days without ever being categorised.

"URL categorisation solutions therefore fail to provide a real-time safety rating of the web content. That level of protection can only be achieved by detecting the intention of the code before the user visits the site," said BenItzhak.

SecureBrowsing runs as an extension to Internet Explorer and Firefox, and will be available for download from Finjan's website in March.