DirectX attack expected - patch Windows now

Following last week's MSBlast worm attack, security experts at Microsoft and other firms are worried that a recently discovered vulnerability in DirectX could cause even more problems

Microsoft seems to have survived the MSBlast worm attack, but now the company is urging Windows users to patch their systems against a different, potentially more dangerous, vulnerability in its software.

Even though most businesses have installed the patch for MSBlast, there is another vulnerability that could completely overshadow last week's events. On 23 July Microsoft posted a security bulletin on its Web site that describes a "critical" vulnerability in DirectX. According to Microsoft, unprotected systems could be at the mercy of an attacker by simply playing a midi file or visiting a malicious Web page.

The danger comes, says Microsoft, in a component of DirectX that relies on a library file called quartz.dll, which is used by a number of applications -- including Internet Explorer -- to play midi files. A specially designed midi file could cause a buffer overflow error and either pass control of the system to an attacker, cause damage to the system or use the system to set off another MSBlast-type attack.

Russ Cooper, chief scientist at security company TruSecure, expects a worm or virus to take advantage of the vulnerability in the near future: "We are definitely afraid of the DirectX vulnerability." The vulnerability, he said, is very widespread because few people have applied the patch for this. Cooper believes it could be exploited by a worm that uses several methods of spreading, similar to the way that MSBlast did.

Graeme Pinkney, analysis operations manager at security company Symantec, said that because the time between vulnerabilities being discovered and exploits being written is decreasing, users have less time to learn about new vulnerabilities and update their systems. "The DirectX vulnerability does have the potential to be exploited, but there are around seven new vulnerabilities found in computer software everyday. Vulnerabilities become a critical issue only when an exploit is released," he said.

Stuart Okin, chief security officer at Microsoft UK, told ZDNet UK: "My real worry is about a more destructive trojan coming on to people's machines. They need to patch their systems, but more importantly, put into place the automatic update. There will be patches that fix problems that are just as large as [MSBlast]," he said. The DirectX patch is available from Microsoft's Web site.

A secure version of DirectX (9.0b) for all Windows versions -- except NT4 -- was released in late July.

Last week's worm attack coincided with the Web site falling over on at least two separate occasions, but the company denies that these faults had anything to do with the worm, which was designed to launch a denial of service attack on the domain.

" went down briefly, but that was a completely different denial of service attack and had nothing to do with the worm," said Okin, who admitted there were a few "flickers" on the Windows Update service as millions of users updated their systems. "It has often been much slower than usual, but it generally handled the traffic without many problems."

Okin said that early estimates indicate traffic on the Microsoft Web site doubled last week when more than 80 million people downloaded the patch. The company also saw the number of calls to its helpline increase 1,400 percent, from 2,000 calls a day to more than 30,000.