Write-Up: SL Online Compiler from FAUST CTF 2019

How to get first blood without understanding the service.

Step 1. Grab a random TCP stream.

Step 2. Test your submitter with it.

Step 3. First blood.

Thanks STT for dumping their flags to us ;)

CALL WRITECHAR 70
CALL WRITECHAR 65
CALL WRITECHAR 85
CALL WRITECHAR 83
CALL WRITECHAR 84
CALL WRITECHAR 95
CALL WRITECHAR 88
CALL WRITECHAR 79
CALL WRITECHAR 108
CALL WRITECHAR 83
CALL WRITECHAR 48
CALL WRITECHAR 72
CALL WRITECHAR 65
CALL WRITECHAR 68
CALL WRITECHAR 116
CALL WRITECHAR 102
CALL WRITECHAR 69
CALL WRITECHAR 87
CALL WRITECHAR 49
CALL WRITECHAR 65
CALL WRITECHAR 65
CALL WRITECHAR 65
CALL WRITECHAR 65
CALL WRITECHAR 65
CALL WRITECHAR 67
CALL WRITECHAR 120
CALL WRITECHAR 121
CALL WRITECHAR 120
CALL WRITECHAR 65
CALL WRITECHAR 68
CALL WRITECHAR 77
CALL WRITECHAR 68
CALL WRITECHAR 107
CALL WRITECHAR 86
CALL WRITECHAR 89
CALL WRITECHAR 77
CALL WRITECHAR 120
CALL WRITECHAR 120
Welcome to SLOC - your Simple Language Online Compiler
What do you want to do?
1 <size>\n<code (size bytes)  Compiles and runs your program
                              Prints the result and gives you an (id, pwd)
                              to get your out again later
2 <id> <pwd>                  Shows to result of the given run again
3                             Lists all recent run ids
FAUST_XOlS0HADtfEW1AAAAACxyxADMDkVYMxx
SUCC: Submission stored with id tmprbxx0oeqR6X2QQ4553S6G437 and pwd 6YL5PNJGSHUCAI3Z