I don't think I get the whole thing either, but my impression is: - Download image for modem firmware. - Extract the filesystem from the image by hacking up a

I don't think I get the whole thing either, but my impression is: - Download image for modem firmware. - Extract the filesystem from the image by hacking up an open source tool. This represents all the files on-disk on the modem. - Search the file system for references to the suspicious port. Locate binary that listens on said port. - Disassemble binary, figure out the protocol/format of messages it's expecting to hear on suspicious port. - Brute force the effect of sending messages by sending messages to said port with the header it's expecting, and different permutations of payloads? (I'm not sure about this part, I might be making shit up) - Using this brute forcing figure out what payloads do what and map out what this backdoor listener can do.