Note: These vulnerabilities remain unpatched at the point of 
publication.  We have been working with Symantec to try and help them to 
fix this since our initial private disclosure in July 2017 (full 
timeline at the end of this article), however no patch has yet been 
released.  Consequently, we are at the point of publishing the findings 
publicly.  We will continue to work with Symantec to help them to 
produce an effective patch.  CVE numbers to follow.

In this article we discuss various approaches to exploiting a 
vulnerability in a kernel driver, PGPwded.sys, which is part of Symantec 
Encryption Desktop [1]. These vulnerabilities allow an attacker to 
attain arbitrary hard disk read and write access at sector level, and 
subsequently infect the target and gain low level persistence (MBR/VBR). 
They also allow the attacker to execute code in the context of the 
built-in SYSTEM user account, without requiring a reboot.

Since many of the exploitation techniques that we come across rely on 
memory corruption, we thought that demonstrating exploitation of this 
type of flaw would be interesting and informative.

We will provide a short overview of the discovery and nature of the 
vulnerability. We will then discuss how access control to file and 
directory objects is enforced by NTFS, attack methods, problems, 
possible solutions to complete the exploit, and their limitations.

Read more here: 
https://labs.nettitude.com/blog/symantec-encryption-desktop-local-privilege-escalation-exploiting-an-arbitrary-hard-disk-read-write-vulnerability-over-ntfs/

Cheers,
kyREcon