It's been a week since hackers released software that could be used to attack a flaw in Windows Vista and Server 2008, but Microsoft and security companies say that criminals haven't done much with the attack.
On Monday, Microsoft said it hadn't seen any attacks that used the vulnerability, an analysis that was echoed by security companies such as SecureWorks, Symantec and Verisign's iDefense unit.
While criminals jumped on a similar flaw a year ago, using it in widespread attacks that ultimately forced Microsoft to rush out a security patch ahead of its monthly set of security updates, that hasn't happened with this latest bug, which lies in the SMB v2 software used by Vista and Server 2008 to do file-and-printer sharing.
SecureWorks researcher Bow Sineath said on Tuesday that there are several reasons why this latest attack has not been picked up. Perhaps the main reason is that the Metasploit code doesn't work as reliably as last year's MS08-067 attack, and often causes the computer to simply crash instead of running the hacker's software.
SMB v2 is typically blocked at the firewall, and it does not ship with Windows XP, meaning that the Metasploit attack will not work on the majority of PCs. Vista, the only Windows client that is vulnerable to the attack, is used on about 19 percent of computers that surf the web, according to web analytics firm Net Applications. Windows XP runs on 72 percent of PCs.
Because of all of these factors, the SMB v2 flaw is simply not "all that popular of a target," Sineath said.
Last week, Dave Aitel, CEO of security tool vendor Immunity, predicted that Microsoft would not need to patch the bug ahead of its scheduled October 13 security patch date.
The Metasploit attack makes certain assumptions about the computer's memory that allow it to work in certain hardware configurations, but in many situations, it simply doesn't work, Aitel said.
"I asked the Immunity team to take a look into the new exploit to assess whether Microsoft would patch the SMB v2 bug early, and our initial assessment is 'No, they will not,'" he wrote in a discussion list post last Tuesday. "Working around this issue in the current public exploit is probably two weeks of work. At that point, we're nearing Microsoft Tuesday and the need for an out-of-band patch is moot."
The Metasploit team is still working on its attack, however. On Sunday, Metasploit posted details of a new way of exploiting the bug and said it was working on a module that takes advantage of this so-called trampoline technique.
If the trampoline method works and makes the Metasploit attack more reliable, criminals are likely to start using it, SecureWorks said.