Cyber Apocalypse 2023 - Reversing - Needle in a Haystack

You’ve obtained an ancient alien Datasphere, containing categorized and sorted recordings of every word in the forgotten intergalactic common language. Hidden within it is the password to a tomb, but the sphere has been worn with age and the search function no longer works, only playing random recordings. You don’t have time to search through every recording - can you crack it open and extract the answer?

Like other reversing challenges, we’re given a binary and that’s it.

When doing reversing challenges, I like to run strings against the binary to see if the flag happens to be visible there. If it is, it can save me a ton of time trying to reverse engineer code.

$ strings haystack
/lib64/ld-linux-x86-64.so.2
srand
time
... lots of strings snipped out for brevity ...
ozglonori
chleatf
kroucalo?
HTB{d1v1ng_1nt0_th3_d4tab4nk5}
huarg
voremtc
glyubyuur
klesalo
.. lots of strings snipped out for brevity ...
.dynamic
.got.plt
.data
.bss
.comment

And we can see the flag is just in the list here.

HTB{d1v1ng_1nt0_th3_d4tab4nk5}

A potentially time-saving addition to running strings in a CTF where you know the format of the flags would be:

$ strings haystack | grep HTB
HTB{d1v1ng_1nt0_th3_d4tab4nk5}

This way a person doesn’t need to actually look through the list, saving valuable seconds.