Sophos issued a statement warning internet users of downloading fake anti-virus products, following the discovery of a malicious Trojan horse that is posing as a free copy of Norton AntiVirus 2008.

According to the IT security company, Google adverts are being presented to internet users who search for “free antivirus”, leading them to a professional-looking website that claims to offer an anti-virus product for download.

The website attempts to lure visiting computer users into installing a Trojan horse, Troj/FakeAV-AD, which will then present fake security alerts and urge users to purchase a “full version” of the software.