DawgCTF 2021: nstftp
Repo related to the challenge "nstftp" from DawgCTF 2021, along with my auxiliary/solution programs used to solve it.
To read the complete challenge write-up, follow this link.
Dir structure
nstftp_chall contains all the files related to the challenge itself, including the original .pcap file with the interactions between an unknown client and server, and also the nstftp server.
The current directory has the 2 programs I made that were used to get the flag, including the nstftp client that complied with the underlying protocol being used, and also the client name crafter used to trigger the backdoor.
Basic usage
Run the ftp server:
user@e27335e10fe2:~/nstftp/nstftp_chall# ./nstftp
Listening on 0.0.0.0:1337
And then with the client:
user@e27335e10fe2:~/nstftp# ./nstftp_client.py localhost 1337
[+] Welcome to NSTFTPv0.1!
[+] Available commands: ls get help crash flag exit
[+] Opening connection to localhost on port 1337: Done
nstftp>
Then the server view should look like this:
user@e27335e10fe2:~/nstftp/nstftp_chall# ./nstftp
Listening on 0.0.0.0:1337
Accepted connection from 127.0.0.1:50194
Forked child pid 1135127
[1135127]: Talking to NSTFTP-client-go-dawgs