According to reports, IT supplier CA's main website has been hacked, with visitors redirected to a Chinese site distributing malware.
The hack is said to have taken place last week, although CA has not issued a report on the attack.
Parts of the press section of the Ca.com portal were affected, re-routing visitors to the uc8010.com domain, which has been hosting malware since last month.
He said, "Unconfirmed reports suggest that the press section of the Ca.com portal is hosted by a third party organisation, but this makes no difference to the visitors, who were being re-directed to the Chinese malware site."
The problem at the CA site is said to be fixed.