Trivia Walkthrough (DefCon CTF 2007 Qualifier)
The Trivia category was mostly a challenge for exercising your Google-foo if you didn't immediately know the answer out-right.
100: ____ the planet
This is the same 100-level question as from 2006, only with a different word dropped. A serious "are you paying attention?" trivia question. :)
Either you immediately recognize this quote and can't stop yourself from shouting "Hack the planet!!", or you have no idea in the world what this could be. This is a quote from the uber-leet movie "Hackers".
200: what OS did kenshoto run for CTF 2006?
If you participated in DefCon CTF 2006, walked past CTF 2006 and heard teams groaning and swearing, or read about details from CTF 2006, you'd know that the OS was Solaris.
300: Who founded the zine TAP?
Perhaps some people know this off the top of their head, but it is findable on Google. The real challenge here is that getting details about the physical zine TAP is tricky due to the electronic zine with the same name. Eventually it was tracked down to Abbie Hoffman.
400: What is the name of the command used to add a user to a OSX box?
If you didn't already know this from your years of OSX user administration work, Google quickly recovered a wealth of tools to use, including "adduser", "nicl", "netinfo", and finally the correct answer, "niutil".
500: Implement the linked piece of C code in one assembly instruction. (submit answers in \x11\x22\x33 bytecode format)
The linked C code read:
for (ecx = 0; ecx < 32; ecx++) {
    if ((1 << ecx) & eax) {
        ebx = ecx;
The first step is simply asking "what does this code do?" It loops 0 through 31. It tests for specific bits (1 << variable). If a bit is set, it records the offset -- but keeps running the loop. At the end, what is left in ebx? The offset of the highest set bit.
In x86 assembly, there is an instruction that performs exactly this way: BSR, or "Bit Search Reverse". So using "bsr %eax,%ebx" will scan eax and set ebx with the offset of the highest bit. In machine code, this is "\x0f\xbd\xd8".

DefCon CTF 2007 quals