Security Concerns regarding the AES key encryption using factory default key

[jeffrey.zhao@iptcloud.com]

Hi all
During the phone initial auto provisioning, the MAC oriented encryption AES key is delivered via the MAC_Security.enc file, which is encrypted with Yealink factory default key.

I am wondering whether there is possibility that the factory default key is leaked via special engineering method, like TTL, hack into the phone OS, etc.