Microsoft confirmed it was the victim of a denial of service attack yesterday, which it said was separate to the human error that crippled its main web properties for much of Tuesday and Wednesday.
In a statement issued late yesterday, the software giant said it was the target of an attack against the routers that direct traffic to the company's web sites, including Microsoft.com and MSN.com. Customers could only gain intermittent access to those sites on Thursday.
Microsoft claimed the attack was not related to any of its products, but an "attempt to interfere" with the routers in one of its internet data centres.
The attack came only a day after an erroneous configuration change by a Microsoft technician rendered the company's domain name system servers inaccessible for most of Tuesday and Wednesday.
In the statement, Microsoft said: "It is unfortunate that an individual or group of individuals would engage in this kind of illegal activity." It added that it has notified the FBI and has taken immediate steps to ensure its websites are accessible.
Analysts believe this week's events are a huge embarrassment for Microsoft, which recently launched a multi-million dollar campaign to promote its web properties. Some observers were also surprised that Microsoft's sites could fall victim to a denial of service attack given that such occurrences are nothing new and that there are numerous products on the market that prevents such events.
Rob Enderle, an analyst at researcher, Giga Information Group, said: "Microsoft should be relatively safe against denial of service attacks as most large sites have policies in place. The fact that Microsoft was attacked means that it was either unprepared or that it was an unusually harsh attack."
He added that attacks on companies are often related to business events and speculated that Microsoft could have been targeted by an individual unhappy about the software giant's settlement with Sun Microsystems over their legal Java dispute, which was announced on Tuesday.
Microsoft has been the victim of a number of hack attacks over the past few months. In October, the company admitted that source code for some of its products under development was seen by hackers who gained access to its corporate network.
Double legal trouble for Musk as he also faces civil lawsuit over renewed British pot-holer 'paedo' claims
Battery development could help boost performance of smartphones
Topological photonic chips promise a more robust option for scalable quantum computers
In quantum physics both the chicken and the egg can come first, claim University of Queensland researchers
Cause-and-effect is not always straightforward in quantum physics