Microsoft owns up to Exchange bug

A flaw has been discovered in Microsoft Exchange server that could leave companies exposed to external hacking via the Internet.

The security hole was discovered by network security firm, Internet Security Systems, which alerted Microsoft immediately. The problem only appears in Exchange versions 5.0 and 5.5.

Microsoft played down the fault, saying that although it can crash servers, there is no danger of data loss or corruption. However, a spokesman for the company said: "Customers concerned about their server should first go to our Web site where we have posted a 'hot-fix' for the problem."

European customers who are still concerned can call Microsoft's Corporate Connections hotline, where operatives have been briefed and are currently working out the best way to help them.

The next service pack for Exchange 5.0 and 5.5 will include a patch for the security hole. Meanwhile, customers can call the Corporate Connections hotline on 0870 6060600.