Google has once again publicly disclosed a zero-day vulnerability in current versions of Windows operating system before Microsoft has a patch ready.
Yes, the critical zero-day is unpatched and is being used by attackers in the wild.
Google made the public disclosure of the vulnerability just 10 days after privately reporting the issue to Microsoft, giving the chocolate factory little time to patch issues and deploy a fix.
According to a blog post by Google’s Threat Analysis Group, the reason behind going public is that it has seen exploits for the vulnerability in the wild and according to its internal policy, companies should patch or publicly report such bugs after seven days.
Windows Zero-Day is Actively being Exploited in the Wild
The zero-day is a local privilege escalation vulnerability that exists in the Windows operating system kernel. If exploited, the flaw can be used to escape the sandbox protection and execute malicious code on the compromised system.
The flaw “can be triggered via the win32k.sys system call NtSetWindowLongPtr() for the index GWLP_ID on a window handle with GWL_STYLE set to WS_CHILD,” Google’s Neel Mehta and Billy Leonard said in a blog post.
“Chrome’s sandbox blocks win32k.sys system calls using the Win32k lockdown mitigation on Windows 10, which prevents exploitation of this sandbox escape vulnerability.”
The blog post also notes that Google reported a zero-day flaw (CVE-2016-7855) in Flash Player to Adobe at the same time as it contacted Microsoft. Adobe pushed an emergency patch for its software last Wednesday.
The Flash Player bug was also being exploited in the wild against organizations in targeted attacks. According to Adobe, the flaw affected Windows 7, 8.1 and 10 systems.
Since the Windows zero-day vulnerability is being actively exploited in the wild, Google shared only basic details about the bug on Monday.
Microsoft has yet to Rolled out a Fix
Needless to say, Microsoft is not at all happy about the disclosure.In response, Microsoft said Google’s disclosure has potentially placed customers at risk, adding that the company believes in coordinated vulnerability disclosure.
This is not the very first time that Google and Microsoft have been at odds over vulnerability disclosure. Microsoft has a long history of bungling patches, so the move could eventually lead the company into quickly rolling out an update.
Meanwhile, users are advised to update their Flash software now and apply Windows patches as soon as they become available.
Google researchers discovered recently that the Windows kernel is affected by a local privilege escalation vulnerability that allows attackers to escape the sandbox.
“[The vulnerability] can be triggered via the win32k.sys system call NtSetWindowLongPtr() for the index GWLP_ID on a window handle with GWL_STYLE set to WS_CHILD. Chrome’s sandbox blocks win32k.sys system calls using the Win32k lockdown mitigation on Windows 10, which prevents exploitation of this sandbox escape vulnerability,” Google said in a blog post on Monday.
Google typically gives companies 90 days to patch vulnerabilities found by its researchers, but vendors are advised to develop fixes or at least provide workarounds within 60 days if the flaw is critical. However, if a security hole is being exploited in the wild, vendors only get 7 days to take action.
On October 21, Google informed Microsoft and Adobe of Windows and Flash Player vulnerabilities that had been actively exploited. Adobe managed to patch Flash Player a few days later, but Microsoft still hasn’t released a fix or an advisory.
“We believe in coordinated vulnerability disclosure, and today’s disclosure by Google could put customers at potential risk. Windows is the only platform with a customer commitment to investigate reported security issues and proactively update impacted devices as soon as possible. We recommend customers use Windows 10 and the Microsoft Edge browser for the best protection,” a Microsoft spokesperson said in an emailed statement.
In the case of Adobe, Google discovered that malicious actors had been exploiting a use-after-free vulnerability (CVE-2016-7855) in limited, targeted attacks aimed at users running Windows 7, 8.1 and 10.
The patches released by Microsoft in October addressed a total of four vulnerabilities exploited in the wild, including weaknesses leveraged by advanced persistent threat (APT) actors in cyber espionage operations and by profit-driven cybercriminals in malvertising attacks.
This is not the first time Google has disclosed Windows vulnerabilities before Microsoft could release a patch. In late 2014 and early 2015, Google Project Zero published the details of several flaws after the 90-day deadline expired. At the time, the company made some changes to its disclosure policy after being criticized by some members of the industry.