World's biggest web-based email service attacked

More than 50million users of Microsoft's Hotmail service are still reeling this morning from news that their private messages were available for all to see.

The story broke in Sweden where a group of eight hackers calling themselves "Hackers Unite" announced that they'd broken security on the MSN system. Swede, Lasse Ljung, speaking on behalf of the crew, claimed that the hack was purely to show that a bug existed. Nine lines of the code needed to sneak into Hotmail were posted to websites in the UK and Sweden.

Microsoft responded by briefly closing Hotmail down on Sunday and by posting a suitably bullish announcement on Hotmail.com. Using cagey language that avoids supporting any claims to a gaping whole in its system, the announcement states that there was a "potential security vulnerability that could enable unauthorized access to Hotmail servers".

The Seattle-based mega-corporation confidently boasts that "...that the issue has been resolved and MSN Hotmail is currently operating normally".

Industry speculation is that the hole that enabled Hackers Unite to open the system - widely used by business people on the road - was a 'back door' built into the system and known to Microsoft. This comes on top of news last week that Windows 98 is vulnerable to a variation of the Melissa virus. This new virus enables hackers to take control of PCs simply by sending an email.

As we go to press, Hotmail is up and running, with Microsoft's share price rising.