Can you use your knowledge of format strings to make the customers happy?
Then, the task provides the links to the binary, code and the live instance for the task.
The full code is provided below.
If we look at the code, there are some printf functions without format string controllable by us that means that here we have again Format string vulnerability. But in this case we do not have full control as there are special checks on values we can proceed to these functions.
Nevertheless, the coices themselves contain parts of format string inside them, for example Gr%114d_Cheese or Cla%sic_Che%s%steak. So, to get the desired output, it can be enough just to make the right choices. Let's try it. The result is shown in Figure 1:
Figure 1: Making the "right" choices
And the application just gave us the flag. No rocket science here. The flag is:
picoCTF{7h3_cu570m3r_15_n3v3r_SEGFAULT_ef312157}