Braindump / Writeups for challenges I've solved and will potentially add more solutions
From the code we can see that eval is called on the option parameter form POST input on the request.
The greetType can be set to the FL4G variable that stores the flag. The number, however, is filtered through the botValidator function.
Only certain operators are allowed and the eval expression's index FL4G[whatever_idx] cannot have more than one number and any character. The operators that are allowed are - and ~ which are the negative and bitwise not operator.
So, using the short little script gen_inputs.py, I generate various positive and negative expressions for the index: ['0', '1', '2', '3', '4', '5', '-~5', '-~-~5', '-~-~-~5', '-~-~-~-~5', '-~-~-~-~-~5', '-~-~-~-~-~-~5', '-~-~-~-~-~-~-~5', '~-~-~-~-~-~-~5', '~-~-~-~-~-~5', '~-~-~-~-~5', '~-~-~-~5', '~-~-~5', '~-~5', '~5', '-5', '-4', '-3', '-2', '-1', ] that iterates over all of the characters in the flag.
This is then sent as a POST request using sol.py and each character of the flag is put together.