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Encrypted RAR and ZIP files


Night_Reaper
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Hi Guys,

I've just started a new job and the previous IT guy has left all his old files in encrypted RAR and ZIP files on the network. He's left now and not answering calls, and I need the stuff in those files. Apart from all the crappy brute force software that's coming up on a simple google search does anyone know a quicker way to get into the files?

Really appreciate the help!

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Probably one of the best tools, http://www.elcomsoft.com/products.html or write your own brute forcer. Without the password, only way to crack it is brute force or get a hold of the person who made the files.

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I would suggest targeting the zip files first as the last time I had do a similar task they were a lot faster to crack. Once you have a password try it on all the other zip and rar files (after all he wouldn't be the first person to use the same password for everything).

Also you did try a dictionary attack first before going for the brute force attack, didn't you? If he is any good with password choice it would fail, but given the cost of running a dictionary attack is so low you might as well give it a shot (perhaps on an old machine you might have laying around).

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I remember using a zip password cracker for VCL back in the 90s, and it worked in a reasonable amount of time on a 133MHz processor. Granted the password was only about 7 characters long, but these days we have much faster processors in our cell phones, you should be able to do a lot better than 24 p/s even with an inefficient shell script.

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I believe elcomsoft has a GPU version of their cracking tool as well, but don't quote me on that. Either way, should be able to do the trick, or like I mentioned, write your own that uses Cuda or OpenCL type threading against the GPU vs CPU and you speed up the process. I think BackTrack even has some winrar and zip file tools built in, but not sure on the threading and if they allow for OpenCL use, etc. Could take a look at other code examples though and maybe work in your own code to convert them to run agianst a GPU instead of the CPU and then recompile and give it a try that way.

Disclaimer** I'm not a programmer, so wouldn't even know where to begin with the converting one program to work from CPU to GPU, but I know people port things like this so it can be done.

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