How does digitally signing the AT jobs eliminate the vulnerability?
It re-establishes the AT command as a point of control. It’s not enough to simply be able to create an AT job with the proper format. If it isn’t digitally signed, it won’t run-and only the AT command can do the digital signature. Because only administrators can run the AT command, only they can create AT jobs. It also prevents malicious users from modifying existing AT jobs. If the contents of an AT job are changed, the verification of the digital signature will fail, and the job will not run.
