Tavis Ormandy, a Google security engineer, reported a critical bug to Microsoft only five days before going public.
The vulnerability has being used by Carbanak group.
Vulnerable component: Windows
CVSSv3 score: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:F/RL:O/RC:C
CWE-ID: CWE-119 - Improper Restriction of Operations within the Bounds of a Memory Buffer
The vulnerability allows a local attacker to obtain elevated privileges on the target system.
The weakness exists due to the failure to properly initialize a pointer for the next object in a certain list by the EPATHOBJ::pprFlattenRec function within kernel-mode driver (win32k.sys). A local attacker can use multiple FlattenPath function calls to obtain write access to the PATHRECORD chain and execute arbitrary code on the system with elevated privileges.
Successful exploitation of the vulnerability results in arbitrary code execution on the vulnerable system.
Note: the vulnerability was being actively exploited.