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I was asked to crack a program in a job interview
51–60 of 309 posts
Re: I was asked to crack a program in a job interview
#52Very nice
My approach would be to disassemble, then try to find the strings in the program and see where they're being used and processed.
And kill the CC thing by hexediting the file
Re: I was asked to crack a program in a job interview
#53This is totally nostalgic of the "binary bomb" assignment in CS 107 @ Stanford. You have to run the program from Stanford's network. There are 6 levels and each level has a password you have to enter. If you enter the wrong password, the course server is notified, and a point is deducted from your grade. The correct way to solve each level is to disassemble the program and figure out what it's doing.
Here's Google's cache of this page:
http://webcache.googleusercontent.com/search?q=cache:uGbSzpZ...
...there's even a secret level in the binary.
Re: I was asked to crack a program in a job interview
#54Is this company ok with this being posted?
If so, they should say what company they are, because being associated with a clever puzzle like this is great for recruiting (even if it's not being used anymore). Unless they have their own reasons for remaining quiet (government? :)).
If not, they should probably take it down, as having the solutions posted would ruin the evaluative value of what must have taken a very long time to make.
Re: I was asked to crack a program in a job interview
#55Earlier quoted context omitted.
What kinds of positions are you interviewing for?
Firmware engineers. Basically C programming and working close to the hardware.
Hmm, as andrewljohnson said, I expect that the posting impacts who applies, but I would expect that to disproportionately turn up applicants who can write C.
Another dynamic at play is the fact that those who don't have useful skills apply more often as they continue to be out of work, that doubtless accounts for some of it.
Still a bit strange.
Re: I was asked to crack a program in a job interview
#56what'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?
The bomb lab discussed elsewhere in this comment thread.
Re: I was asked to crack a program in a job interview
#57This is totally nostalgic of the "binary bomb" assignment in CS 107 @ Stanford. You have to run the program from Stanford's network. There are 6 levels and each level has a password you have to enter. If you enter the wrong password, the course server is notified, and a point is deducted from your grade. The correct way to solve each level is to disassemble the program and figure out what it's doing. Here's Google's…
We did that in our second year and it was awesome. I don't know if it was the same binary but it was well made. The first password was very easy (just a constant string) and it got progressively harder from there. At the end we had to step through some recursive algorithm and you learned to read assembly almost as well as normal code. And the server for submitting the passwords didn't filter the username so you could enter arbitrary HTML into the high-score...
Re: I was asked to crack a program in a job interview
#58Really nice overview of the process. I was hoping to get into debugging and breaking code, but my career took a wild turn away from that part of the job. It's still something I would like to learn, so I'm reading as much about it as I can. I'm going to take this way off topic here, but it's a curiosity of mine. Please don't take this as an insult; it seems to be very common and as a language learner myself I'm just w…
> In this case, Spanish
In Spanish you put a space after periods and commas, so that's not it.
Re: I was asked to crack a program in a job interview
#59Earlier quoted context omitted.
Could be inside docker. In which case it's all reasonable.
Afraid you're woefully incorrect. The root user is no more contained inside a default docker image than they are inside a chroot, which is, not really at all. It isn't difficult to break out of a container if you have uid 0 aka root. This will change when the userns stuff lands, but it hasn't yet, so that doesn't count yet. https://opensource.com/business/14/9/security-for-docker Or as solomon hykes, the docker creat…
Well, so far I have only heard a lot of FUD and nothing concrete.
http://opensource.com/business/14/7/docker-security-selinux seems to have some information. But to refuse the points there, on my system: a) docker containers do not have a /dev/mem b) /sys/fs is mounted read-only c) /dev/sd* is not visible
And so on. What's the thing with cgroups? Can a container delete the host's cgroups? Can it overwrite it's own cgroup constraints?
Can you or someone tell me if there is something I can try out on my own to understand actual issues? I run my containers unprivileged (which is the default) if it matters.
Again, all I am asking is for some material to educate myself on what actually the flaws are. All I have seen are vague articles claiming it's insecure.
Re: I was asked to crack a program in a job interview
#60I 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 is fairly basic stuff. If you want to meet hundreds of people who do things like this every day you could attend RECon in Montreal.
Or send me an email. We're an expensive group to hire though. :-)