Challenge Overview
Can you figure out what is in the eax register? Put your answer in the picoCTF flag format: picoCTF{n} where n is the contents of the eax register in the decimal number base. If the answer was 0x11 your flag would be picoCTF{17}.
Download the assembly dump here.
Solution
wget https://artifacts.picoctf.net/c/510/disassembler-dump0_b.txt
cat disassembler-dump0_b.txt
You can see where "eax" is there is "DWORD PTR [rbp-0x4]". So it is pointed to [rbp-0x4] which has a value of 0x9fe1a.
To convert this hex to decimal you can use an online tool, or various method in the command line to do this. I initially used the printf method.
printf "%d" 0x9fe1a
The contents of that command wrapped in picoCTF{} is the flag.
n being the number found from the conversion.
Flag: picoCTF{n}