CVE-2018-6856: Improper Restriction of Operations within the Bounds of a Memory Buffer

Sophos SafeGuard Enterprise before 8.00.5, SafeGuard Easy before 7.00.3, and SafeGuard LAN Crypt before 3.95.2 are vulnerable to Local Privilege Escalation via IOCTL 0x8020601C. By crafting an input buffer we can control the execution path to the point where a global variable will be written to a user controlled address. We can take advantage of this condition to zero-out the pointer to the security descriptor in the object header of a privileged process or modify the security descriptor itself and run code in the context of a process running as SYSTEM.