It's quite interesting how the command set has been extended for modern needs, for example see: https://www.u-blox.com/sites/default/files/u-blox-CEL_ATComm...
[0] " There were programs here that had been written five thousand years ago, before Humankind ever left Earth. The wonder of it—the horror of it, Sura said—was that unlike the useless wrecks of Canberra’s past, these programs still worked! And via a million million circuitous threads of inheritance, many of the oldest programs still ran in the bowels of the Qeng Ho system. Take the Traders’ method of timekeeping. The frame corrections were incredibly complex—and down at the very bottom of it was a little program that ran a counter. Second by second, the Qeng Ho counted from the instant that a human had first set foot on Old Earth’s moon. But if you looked at it still more closely. . .the starting instant was actually some hundred million seconds later, the 0-second of one of Humankind’s first computer operating systems. "
Spectre/Meltdown are a good example of what happens when (after a couple of decades) the security guys finally understand what the architecture looks like at that level and start looking for vulnerabilities.
This is also why you should be wary of devices and especially device drivers. This is why binary blobs in drivers are such a butt clencher. And then you're talking about drivers that are stupendously large and are more or less attached directly to your web browser.
Signed binaries make that a lot harder.
Also used in voting machines which "aren't connected to the internet" (!)
e.g. https://freedom-to-tinker.com/2018/02/22/are-voting-machine-...
Some of these GSM modems have AT-commands to upload & run sophisticated, persistent LUA scripts. (Scripts that can can make tcpip connections over GSM, communicate to host hardware via I2C or uart, send SMSs, etc). The possibilities are wide ranging, using officially supported features; no hacking necessary.
see: https://simcom.ee/documents/SIM5320/simcom_lua_application_n...