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Computerworld - Microsoft today delivered six security updates that patch nine vulnerabilities, fixing two bugs already being used by hackers but leaving one still open to exploit.

Of the six bulletins, three patched some part of Windows, while the remainder plugged holes in Publisher, Internet Security and Acceleration Server (ISA) and Microsoft's virtualization software. Six of the nine bugs were ranked critical, Microsoft's highest ranking in its four-step score, while three were tagged as "important," the next-lowest label.

"We got what we expected," said Andrew Storms, director of security operations at nCircle Network Security. "We got the 'kill bit' we were looking for in the ActiveX control and the DirectShow fix," he said, referring to two recent vulnerabilities that attackers have been exploiting for weeks.

In May, Microsoft acknowledged that hackers had begun exploiting a bug in DirectShow, one of the components in Windows' DirectX graphics platform. Last week, it owned up to another bug, this one in a video streaming ActiveX control used by Internet Explorer (IE) -- and admitted it had known about, but not fixed, the flaw for the past 18 months.

Microsoft patched the already-public DirectShow flaw with MS09-028, and for good measure tucked in fixes for two more vulnerabilities also reported by researchers.

The "kill-bit" update in MS09-032 didn't actually patch the underlying ActiveX problem. Instead, Microsoft simply disabled the control, effectively shutting off any possible attack by modifying the Windows registry using the update. Microsoft offered the same protective measure via an automated tool last week, but that required users to manually browse to a support document, then download, install and run the tool.

Researchers unanimously voted those two updates as the ones to deploy immediately. "Microsoft did well to get out the two zero-days," said Eric Schultze, chief technical officer at Shavlik Technologies, "especially the ActiveX. It was a little much to ask them to get out the Office ActiveX fix, though."

Schultze was talking about a bug in an ActiveX control used by Office Web Components to display Excel spreadsheets in IE. Microsoft warned users of the vulnerability only yesterday. By today, Web attacks had rapidly increased. On Monday, however, Microsoft said that it wouldn't wrap up a fix in time for today's release.

Like the DirectShow ActiveX flaw that was patched today, Microsoft has released a "Fix It" tool that users can download and run themselves to kill the control. But, according to Schultze, Microsoft's not planning to push a kill-bit update to users for this second flaw. "Setting the kill bits actually impedes functionality," Schultze said. "Microsoft told me today that they're working on a file-level fix."