Microsoft has revealed that it has also "recently experience a similar security intrusion" to the hacking attacks on Facebook and Apple. In a statement on the Microsoft Security Response Center blog, Microsoft's Matt Thomlinson says a "small number of computers" were found to be infected with malware, including some in the company's Mac business unit. "We have no evidence of customer data being affected and our investigation is ongoing," says Thomlinson.

It appears that the attacks are related to a Java vulnerability that has hit a number of firms, including Twitter, Apple, and Facebook. A popular iPhone developer website, iPhoneDevSDK, was recently patched to prevent a malware issue that infected employee computers at Facebook. Microsoft says this type of attack is "no surprise" to it and other companies, but the company's admission comes days after similar ones by other firms. The software giant says it followed its own security response practicses and "chose not to make a statement during the initial information gathering process."