Asterisk AMI Originate Authenticated Remote Code Execution

On Asterisk, prior to versions 18.24.2, 20.9.2, and 21.4.2 and certified-asterisk versions 18.9-cert11 and 20.7-cert2, an AMI user with write=originate may change all configuration files in the /etc/asterisk/ directory. Writing a new extension can be created which performs a system command to achieve RCE as the asterisk service user (typically asterisk). Default parking lot in FreePBX is called "Default lot" on the website interface, however its actually parkedcalls. Tested against Asterisk 19.8.0 and 18.16.0 on Freepbx SNG7-PBX16-64bit-2302-1.