Grandstream UCM62xx IP PBX sendPasswordEmail RCE

This module exploits an unauthenticated SQL injection vulnerability (CVE-2020-5722) and
a command injection vulnerability (technically, no assigned CVE but was inadvertently
patched at the same time as CVE-2019-10662) affecting the Grandstream UCM62xx IP PBX
series of devices. The vulnerabilities allow an unauthenticated remote attacker to
execute commands as root.

Exploitation happens in two stages:

1. An SQL injection during username lookup while executing the "Forgot Password" function.
2. A command injection that occurs after the user provided username is passed to a Python script
via the shell. Like so:

/bin/sh -c python /app/asterisk/var/lib/asterisk/scripts/sendMail.py \
password '' `cat
This module affect UCM62xx versions before firmware version 1.0.19.20.