Google has purchased browser security software vendor GreenBorder for an undisclosed sum. 

The search giant told vnunet.com that the acquisition was completed earlier this month, but declined to provide specific terms of the deal. 

A notice on GreenBorder's website says that the company has stopped selling its security software, and that customers will be supported until their existing contracts expire. 

GreenBorder's software prevents web-based attacks that target browser vulnerabilities in Firefox and Internet Explorer.  

The software uses a virtualisation technique known as a 'sandbox', in which the browser runs entirely within a separate secured system.

This prevents any attacks or exploits from using flaws in the browser to access system resources and run malware.

Microsoft uses a similar method in its Microsoft Office Isolated Conversion Environment.

Google has issued no formal announcement on its corporate site or company blog, and has not announced plans for a new GreenBorder-based service.