Sources:
https://bits-please.blogspot.ca/2016/05/qsee-privilege-escalation-vulnerability.html
https://github.com/laginimaineb/cve-2015-6639

Qualcomm's Secure Execution Environment  (QSEE) Privilege Escalation Exploit using PRDiag* commands (CVE-2015-6639)


Proof of Concept:
https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/39757.zip