At least 40,000 Web sites recently were hacked and retrofitted with instructions that silently attempt to infest visitor PCs with malicious software, security experts warn. Internet security firm Websense has dubbed this series of attacks “Beladen,” because the infected sites divert visitors to a site called beladen.net — one of at least two exploit domains implicated in this attack (this domain actively serves malicious software, so please do not visit it). Stephan Chenette, a senior security researcher at Websense, said the company is not sure how the attackers are breaking into the hacked sites, and that it is still in the process of determining what the malware installed on victim’s PCs actually does. However, each hacked Web page shares the same blob of obfuscated Javascript code, which is appended to the bottom of the hacked page’s HTML. Each hacked site redirects to Web sites that bombard the visitor’s PC with