A PBX – Discovering a Firmware Backdoor

[todsacerdoti]

https://blog.redteam-pentesting.de/2021/inside-a-pbx/

[lrvick]

When a backdoor is so obviously intentional, and perhaps state sponsored, one has to wonder if the vendor "fix" is to simply hide it better.

[josephcsible]

This kind of backdoor would be way harder to avoid detection if the vendor used a reproducible build process and published their source code.