Tries --:--:-- left
Next hack in --:--:--
Warm-up

Your first hack, in 60 seconds

Every Daily Hack works the same way: read the briefing, look at the evidence, type the answer. Try it here first - no XP, no pressure.

Mission briefing

Developers sometimes leave notes in a page's source code that visitors never see. This login page ships one. Read the source below and find the staff password.

Investigate
<form action="/login" method="post">
  <input name="user" placeholder="Username">
  <input name="pass" type="password" placeholder="Password">
  <!-- TODO: remove before launch - staff password is "sunrise" -->
  <button>Sign in</button>
</form>
Your answer
Daily Hack #99 First blood Malekith Solved by alviturino Porthos Sipmaster Ateriana Morddock GreenSanity

Bigger than it says

Reverse Engineering & Binary Exploitation Difficulty Medium ~4 min +10 XP
Mission briefing

Every night at 02:00 the avatar thumbnailer falls over on one file and takes the whole worker pool with it. The file is 46 KB on disk, it is a valid PNG, it opens in a browser, and the upload log records it as a 64 by 64 icon. Nothing about the size on disk explains a machine running out of memory. A PNG carries its pixel dimensions in the header, in plain view, long before a decoder ever touches the compressed data. Read them out of the dump and give the real width. The first eight bytes are highlighted, hovering any byte prints its offset and ASCII character, and the signature reference under the dump names each chunk.

Investigate
Your answer

Play freely - sign up to submit your answer and earn XP.

Solved! +10 XP
First blood! You were first to crack today's hack.
How it works

Up next Pro
Play next hack

Nice one!

Sign up free to claim your +10 XP and start your streak.

Claim +10 XP - sign up free
28,000+ Hackers 100+ Labs & Courses Free
Start Hacking Free