Nine vulnerabilities in Windows, Exchange, SQL Server and Microsoft's Domain Name System (DNS) server and client software have been fixed in the company's monthly round of 'Patch Tuesday' updates.

All nine flaws were rated 'important' by Microsoft, the second-highest threat rating in the company's four-step scoring system.

One of the Microsoft fixes for Windows DNS was part of a group of patches issued on Tuesday by software vendors to plug a multi-platform hole. The researcher who uncovered the vulnerability called the group patch effort the "largest synchronised security update in the history of the internet".

Microsoft patched its iterations of DNS in MS08-037, the security bulletin that called out two DNS bugs in every supported version of Windows except Vista.

"We've had four updates to Microsoft's DNS since 2007 - and one led to a bot, Rinbot, in April 2007," noted Andrew Storms, director of security operations at nCircle Network Security.

Storms was referring to the episode last year when researchers spotted then-new variants of Rinbot exploiting a zero-day flaw in Windows DNS Server Service. The most recent patch for Windows DNS was released as MS08-020 in April, part of that month's eight-update, 10-fix batch of updates.

The fix for the DNS cache-poisoning vulnerability, which Dan Kaminsky, a noted researcher and director of penetration testing with Seattle-based IOActive, reported to Microsoft, is part of a larger, coordinated rollout. Internet Software Consortium (ISC) has also updated its popular open-source BIND DNS software, which vendors like Red Hat and Sun Microsystems are also pushing to their users.

"This is pretty bad, pretty bad," said Kaminsky. "I wish I could go into full detail, but ..."

Kaminsky, who held a news conference on Tuesday with Jerry Dixon, former director of the national Cyber Security Division at the Department of Homeland Security, to discuss the DNS cache poisoning bug, said he would withhold specifics of the vulnerability for about a month. He plans to present his findings at the Black Hat security conference, which takes place between 2 - 7 August in Las Vegas.

"But look at how many people have worked this entire year to make this happen," Kaminsky hinted. "This is not your every-day vulnerability. There are vulnerabilities and then there are vulnerabilities. But that doesn't mean you panic."

He predicted that exploits will be crafted for the DNS flaw. "I don't think this will survive reverse engineering".

Storms of nCircle put it into perspective. "A reliable DNS cache exploit means that the probability of redirecting an unsuspecting user to a malicious website has just increased dramatically," he said, urging users - enterprise administrators in particular - to install the patch pronto. "Every network administrator in the world needs to drop that iPhone, get off their BlackBerry and patch their DNS now."