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I was asked to crack a program in a job interview

erenyagdiran.github.io

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

#81

Post by psychometry »

davidgerard wrote: post #46

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 i…

It's an effective strategy from the employer's side, but what about the applicant who is asked to spend hours on some test for every job he/she applies for? Are you paying these applicants for the time they spend jumping through these hoops?

And if your "technical grilling" fails to identify strong candidates, you're obviously asking the wrong questions or, at the very least, not asking the right ones.

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

#82

Post by sillysaurus3 »

ckaygusu wrote: post #69

I also tried to crack exactly this program a while ago. The company (I believe it is MilSoft, one of the most reputable software companies in Turkey) sent this challenge to university students to hire a part-time CS student. Nevertheless, this was the first time I've ever attempted to crack something and while I had little to no idea what was going on, it was a very thrilling experience. I think I went on 14 hours wi…

At the end of every iteration (of something involving this loop which I can't precisely recall now) the program checks whether it is running under debug mode (essentially makes a PTRACE call and reads its output, the OP also talks about it) If this is the case, it makes a jump to random address, so even if you are just neatly watching the program run under debug mode, you weren't going to achieve anything.

Could you change the jmp into a nop? That should let you attach in debug mode.

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

#83

Post by nekitamo »

jonahx wrote: post #44

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?

https://tuts4you.com/

The lena151 tutorials are especially good:

https://tuts4you.com/download.php?list.17

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

#84

Post by B5geek »

davidgerard wrote: post #46

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 i…

A nice simple test that I like to give as a first-wave elimination:

Have a computer setup and running (all properly configured). Pull the network cable out of the jack a little bit (so it looks like it's plugged in but isn't). Ask the person being interviewed to show me an IP being used by microsoft or google. (so ping/dig/nslookup/etc)

Let the person know that (a) the computer is in working condition (i.e. no drivers are missing) (b) the network works (i.e cables are good, switch is good, DHCP is enabled, etc.) (c) tell them that this is a test to determine their troubleshooting skills

It is always disappointing to see how few ever open a term/cmd window (depending on the OS). 90% of participants just try to open a web-browser and type in "what is the IP address of google"

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

#85

Post by sillysaurus3 »

psychometry wrote: post #81
davidgerard wrote: post #46

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 i…

It's an effective strategy from the employer's side, but what about the applicant who is asked to spend hours on some test for every job he/she applies for? Are you paying these applicants for the time they spend jumping through these hoops? And if your "technical grilling" fails to identify strong candidates, you're obviously asking the wrong questions or, at the very least, not asking the right ones.

I would rather spend hours on some test than be judged on a whiteboard problem, or any other problem which has nothing to do with programming on an actual computer that has an internet connection.

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

#86

Post by vault11th »

psychometry wrote: post #81
davidgerard wrote: post #46

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 i…

It's an effective strategy from the employer's side, but what about the applicant who is asked to spend hours on some test for every job he/she applies for? Are you paying these applicants for the time they spend jumping through these hoops? And if your "technical grilling" fails to identify strong candidates, you're obviously asking the wrong questions or, at the very least, not asking the right ones.

Nobody puts a gun to applicant's head and forces him to take a test, so... Business is not for people to have jobs but to make profit.

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

#87

Post by ckaygusu »

sillysaurus3 wrote: post #82
ckaygusu wrote: post #69

I also tried to crack exactly this program a while ago. The company (I believe it is MilSoft, one of the most reputable software companies in Turkey) sent this challenge to university students to hire a part-time CS student. Nevertheless, this was the first time I've ever attempted to crack something and while I had little to no idea what was going on, it was a very thrilling experience. I think I went on 14 hours wi…

At the end of every iteration (of something involving this loop which I can't precisely recall now) the program checks whether it is running under debug mode (essentially makes a PTRACE call and reads its output, the OP also talks about it) If this is the case, it makes a jump to random address, so even if you are just neatly watching the program run under debug mode, you weren't going to achieve anything. Could you…

I believe it was also the part of the key.

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

#88

Post by kamilafsar »

Swizec wrote: post #8
freehunter wrote: post #5

Really 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…

As far as I know, punctuation association rules are the same in all indo-european languages. Most of them bind to the left and have a space to the right. Emdash, and ... have two spaces, and endash and apostrophe have no spaces. But people struggle with this. I distinctly remembering practicing this in class when prepping for matura (Slovenian version of SATs) so I guess it isn't inherently obvious to everyone.

FWIW, Turkish is not an Indo-European language. It's an Altaic language [1] like Mongolian, Japanese, Korean, etc. Though, it looks like one because Ataturk (founder of Turkey) converted the Turkish alphabet from Arabic script to Latin script when the new republic was found.

[1] http://en.wikipedia.org/wiki/Altaic_languages

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

#89

Post by Ysx »

mahmoudimus wrote: post #42

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.

If it's no relevance to the job, you're only testing that they share your interests.

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

#90

Post by eyeareque »

scott_karana wrote: post #14
meepmorp wrote: post #9

> Here is the first thing i typed in the terminal root@lisa:~# ./CrackTheDoor Um. I see at least one security issue already.

Not sure why you're getting downvoted, but debugging a "crack me" app while running as root is probably a bad idea. Even if this is inside a VM, it might give the wrong message to someone wanting to try this for themselves.

You could also attack the VM:

http://www.cvedetails.com/vulnerability-list/vendor_id-93/pr...

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