OneByOne [LA CTF 2024]

Challenge Description

One….. by………. one…………… whew I’m tired, this form is waaaaaaay too long.

Note: the flag does have random characters at the end - that is intentional.

Intuition

I may have to use the same technique as in the Infinite loop challenge, so let’s look at the source code.

Solution

In the script tag, we see a huge list of characters that we can choose from the select. I quickly noticed a weird pattern where all characters have the same number except one per list. By taking note of the character with the different number for every list, I was able to reconstruct the flag.

Putting the script in a beautifier can help.

… SNIP …

Flag

lactf{1_by_0n3_by3_un0_*,\"g1'}