• The product rule of exponents is the key here.
• openssl commandline didn't work for me in -raw, so I used python instead.
• The python requests api is handy for linking the rsa_oracle http query into the script for an all in one solution.

Is this challenge broken? I have the plaintext, which is ASCII encoding of something meaningful, but it is rejected.

Maybe the server is broken. I got a rejection message, but now it says that I have already solved it.