Didn't read all the leaks but it seems a bit wild to conclude a vendor implemented a backdoor purposefully. There's some been found ofcourse, but simply being SIGINT capable, why does that imply 'backdoor'.? If they have a nice exploit for the device it would also make it SIGINT capable no? without the vendor's cooperation (apart perhaps from a buggy implementation.)

If you have the chip, you can find the backdoor... if you cannot find it, you can't conclude its actually there. There's ways to analyse chips to see if they are backdoored. Decapping, fuzzing and whatnot. Simply basing such of a conclusion from a few lines in a document seems a bit off to me...

Did anyone actually find the thing??