New bug hits Windows DNS service

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A vulnerability in the Domain Name System (DNS) service in Windows 2003 server could allow hackers to take over servers and run remote code.

According to a security advisory from Microsoft, the flaw affects Windows 2000 Server Service Pack 4, Windows Server 2003 Service Pack 1 and Service Pack 2. Its initial investigations revealed that attempts to exploit this vulnerability could allow an attacker to run code in the security context of the DNS server service, which by default runs as local system.

"Upon completion of this investigation, Microsoft will take appropriate action to help protect our customers," the company said on its advisory. "This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs."

The bug was brought to light by the French Security Incident Response Team. It found that flaw was caused by a stack overflow error in the Windows DNS Server's RPC interface implementation when processing malformed requests sent to a port between 1024 and 5000.

According to the organisation, this vulnerability is currently being exploited in the wild. It said as a workaround system administrators should disable remote management over RPC capability for DNS servers or block unsolicited inbound traffic on ports 1024 to 5000, until a fix is developed.

The news of the vulnerability comes just days after Microsoft released patches for four critical flaws in Windows and its Content Management Server software. At the beginning of the month the company had to release an out-of-cycle patch for a vulnerability affecting the way Windows handles animated cursors.

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