Another month, another zero-day vulnerability. Microsoft is investigating new reports of a vulnerability in a kernel component of Windows XP and Windows Server 2003, accessed using older versions of Adobe Reader.
Redmond said it is aware of limited, targeted attacks that attempt to exploit the flaw. The good news: The company's investigation of the vulnerability has verified that it does not affect customers who are using operating systems newer than Windows XP and Windows Server 2003.
"The vulnerability is an elevation-of-privilege vulnerability. An attacker who successfully exploited this vulnerability could run arbitrary code in kernel mode," Microsoft explained in an alert. "An attacker could then install programs; view, change, or delete ; or create new accounts with full administrative rights."
There is one mitigating factor that could work in an enterprise's advantage. An attacker needs to have valid log-on credentials and be able to sign in locally to exploit the vulnerability. In other words, the vulnerability could not be exploited remotely or by anonymous users.
There's also a workaround: For environments with non-default, limited user privileges, Microsoft said disabling NDProxy.sys will cause certain services that rely on Windows Telephony Application Programming Interfaces to not function. Services that will no longer work include Remote Access Service, dial-up networking, and virtual private networking.
Redmond is working with partners in its Microsoft Active Protections Program to provide that they can use to deliver broader protections to customers. Microsoft promised to take the appropriate action to protect customers when the investigation is complete and did not rule out an out-of-cycle patch.
Adobe Reader Connection
We turned to Wolfgang Kandek, CTO at Qualys, for his take on the vulnerability. He told us the exploit is being abused in the wild in conjunction with the Adobe Reader vulnerability that had a fix published in August 2013: "Users that have the latest version of Adobe Reader are immune to the attack, as well as users that are running on Windows Vista or later."
FireEye was the first to uncover the vulnerability. The research firm said the exploit targets Adobe Reader 9.5.4, 10.1.6, 11.0.02 and earlier versions on Windows XP SP3.
"Those running the latest versions of Adobe Reader should not be affected by this exploit," security researchers Xiaobo Chen and Dan Caselden of FireEye wrote in a blog post. "Post exploitation, the shellcode decodes a PE payload from the PDF, drops it in the temporary directory, and executes it."