I was asked to crack a program in a job interview • Hacker News Board

Re: I was asked to crack a program in a job interview

#41

Post by vezzy-fnord » Wed, Sep 17, 2014, 7:59 PM UTC

pkaye wrote: post #22

I don't know where you find candidates that can even approach this level of skill or desire to solve puzzles. Most people I interview struggle with a few lines C program coding.

It's an infosec job, so this kind of thing is actually quite appropriate. Though of course, perhaps not so much depending on the exact area, e.g. for network security it would not be as relevant compared to application security.

Re: I was asked to crack a program in a job interview

#42

Post by mahmoudimus » Wed, Sep 17, 2014, 8:01 PM UTC

I have a pretty cool crackme that I programmed and I wanted to offer it as a puzzle to some candidates, but without the proper reverse engineering tools, I think most candidates would really struggle -- especially if you're looking for just general developers.

Haven't given it much thought past this.

Re: I was asked to crack a program in a job interview

#43

Post by imaginenore » Wed, Sep 17, 2014, 8:04 PM UTC

If we asked questions like that at our interviews, it would take us 10 years to hire one candidate. Most people fail at basic basic stuff.

Re: I was asked to crack a program in a job interview

#44

Post by jonahx » Wed, Sep 17, 2014, 8:04 PM UTC

what's a good, simple intro to the basics of this kind of cracking for someone who is an experienced programmer, knows some C, etc, but has little system level or assembly experience?

Re: I was asked to crack a program in a job interview

#45

Post by pkaye » Wed, Sep 17, 2014, 8:08 PM UTC

dllthomas wrote: post #31

pkaye wrote: post #22

I don't know where you find candidates that can even approach this level of skill or desire to solve puzzles. Most people I interview struggle with a few lines C program coding.

What kinds of positions are you interviewing for?

Firmware engineers. Basically C programming and working close to the hardware.

Re: I was asked to crack a program in a job interview

#46

Post by davidgerard » Wed, Sep 17, 2014, 8:08 PM UTC

Real-life tests are THE best thing to send job candidates. It scales well (you don't have to spend personal hours on them) and you get real information.

This applies even to sysadmins. We have a favourite: set up a VM with a slightly-broken application in a slightly-broken Apache and Tomcat, and get them to ssh in and document the process of fixing it. Even people who aren't a full bottle on Tomcat will give useful information, because we get an insight into their thought processes. I recommend this to all.

(I note we've just done a round of interviews where we get a nice-looking CV and conduct a technical grilling. Hideous waste of time for everyone involved. All CVs should be regarded, on the balance of probabilities, as works of fiction. Do a remote self-paced test like this. You won't regret it.)

Re: I was asked to crack a program in a job interview

#47

Post by davesque » Wed, Sep 17, 2014, 8:08 PM UTC

wyc wrote: post #4

This reminds me of the popular binary bomb lab offered in some computer architecture courses: http://csapp.cs.cmu.edu/public/labs.html

Yep, did those at University of Colorado Boulder.

Re: I was asked to crack a program in a job interview

#48

Post by codexon » Wed, Sep 17, 2014, 8:10 PM UTC

pkaye wrote: post #22

I don't know where you find candidates that can even approach this level of skill or desire to solve puzzles. Most people I interview struggle with a few lines C program coding.

This looks like a standard crack-me.

Most programmers don't need to know how to do this. As it says in the blog he is applying for a security position.

It all comes down to how well you can translate assembly code.

Re: I was asked to crack a program in a job interview

#49

Post by jere » Wed, Sep 17, 2014, 8:10 PM UTC

zellyn wrote: post #2

If this sounds fun, give microcorruption.com a try :-)

Yes microcorruption was a lot of fun and the last part of this post reminds me very much of the last level.

The nice thing about microcorruption was how you didn't need much more than familiarity with assembly and C (and language of choice in the end game). This interview challenge on the other hand... I wouldn't even know where to start.

Re: I was asked to crack a program in a job interview

#50

Post by davesque » Wed, Sep 17, 2014, 8:11 PM UTC

mathrat wrote: post #6

wyc wrote: post #4

This reminds me of the popular binary bomb lab offered in some computer architecture courses: http://csapp.cs.cmu.edu/public/labs.html

Haha, if that's the one I remember you could completely trivialize that lab by fiddling with the program counter in gdb (skipping the line that sets off the bomb). Don't know if they were able to fix that in later versions of the lab. Good times, thanks for reminding me.

That was the point. When I did them, the TA encouraged us to do that. I'm pretty sure they had other measures in place that would have made it hard to fake an authentic success signal to the server. Furthermore, if you sent a corrupted one, you'd lose all credit for the assignment.