Google reveals third unpatched Windows zero-day vulnerability in a month

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Google ignored Microsoft’s calls for flexible vulnerability disclosure deadlines and released details of another unpatched Windows flaw, leaving users exposed for at least the next 25 days.

The new vulnerability, which was confirmed on Windows 7 and 8.1, might constitute a security feature bypass for the way applications can encrypt their memory so that data can be exchanged between processes running under the same logon session.

“The issue is the implementation in CNG.sys doesn’t check the impersonation level of the token when capturing the logon session id (using SeQueryAuthenticationIdToken) so a normal user can impersonate at Identification level and decrypt or encrypt data for that logon session,” the Google Project Zero researchers said in a description of the flaw. “This might be an issue if there’s a service which is vulnerable to a named pipe planting attack or is storing encrypted data in a world readable shared memory section.”

According to Project Zero, Microsoft was notified of the vulnerability on Oct. 17 and initially planned to fix it during its January Patch Tuesday, three days ago. However, the fix had to be postponed because of compatibility issues.

The Google researchers were unmoved by this and stuck to their 90-day public disclosure deadline, publishing details of the flaw and a proof-of-concept exploit Thursday.

The fix is now expected to be among Microsoft’s scheduled security updates on Feb. 10, although there’s no guarantee that it won’t be further delayed. Of course, Microsoft has the option to release an out-of-band patch at any time, but the company rarely does this and when it does, it’s typically for critical flaws that attackers are actively exploiting.

This is the third unpatched Windows vulnerability that Project Zero researchers have publicly disclosed over the past month because Microsoft could not issue fixes before the 90-day disclosure deadline enforced by Google.

On Sunday, Microsoft publicly denounced Google’s inflexibility with vulnerability disclosure, arguing that researchers should work with affected companies until a fix is produced before going public.

“We believe those who fully disclose a vulnerability before a fix is broadly available are doing a disservice to millions of people and the systems they depend upon,” Chris Betz, senior director with Microsoft’s Security Response Center, said in a blog post at the time.

However, other researchers feel that 90 days is more than enough for a software vendor, especially one the size of Microsoft, to fix a vulnerability.

Microsoft is just “whining” over its own inability to respond to bugs in a timely manner after over a decade of using its dominant position to dictate how vulnerabilities should be handled, said Robert Graham, the CTO of security research firm Errata Security in a blog post Monday. “It’s now Google who sets the industry’s standard for reporting vulnerabilities,” he said.

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