noxale

In this challenge, we’re given a 32 bit ELF executable(DEP enabled), a “custom” libc, and a C source.

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In that challenge we only got a 7z file called en.7z that contained 900 images. We quickly noticed that the images connected to each other, for example images 186-188 had the same head in them so we needed to connect the images but how can we know the size of a row? There were many blocks of 4 gray images that were the border (the first row was all gray too) so we can see that each row had 30 images, now we only need to connect them. [Read More]

The task: Rick was developing a patch for time machine, but his love for alcohol products slowed the process. The only thing he managed is to write one line of code, and booze finished the rest. After finishing work on the project he was able to behold his creation more sober eyes. Then he got drunk again. As it turned out, clouding his mind, Rick did not create a workable patch, just a puzzle. [Read More]

The Task Grandpa! I paid one hacker 5 thousand rubles and he cheated on me! I asked him to hack the e-diary and make my marks better. He did nothing and disappeared! Don’t worry, I have fellows, who will help us to find him. Tell me where did you find him. I found a telegram bot, there was an anonymous chat for hackers with disappearing messages mode on. The only thing I can tell — his id in this chat is 13. [Read More]

The task Abradolf Lincler decided to destroy the most valuable monument on earth. To this end, he has selected the top 10 monuments and photographed each to have a final choice. Rick tried to stop him, but all he managed to get somewhat of hard disks from his computer. Rick also learned that Lincler chosen for its sinister action of the Statue of Liberty. Find out in what city Lincler preparing your act of vandalism to stop him. [Read More]

NothingToSee is an easy-medium steganography task I have wrote in-order to show a method of using visual way to see things. You get one PNG file, with nothing you can see. To solve that, you must to look on the alpha channels in the picture, you can see that all the alphas are 0 or 1 so you save it all as a string in case it’s related to binary data. [Read More]

So, this is a medium-hard crypto challenge with a little bit of forensic. The solver gets a server and port and a description says: “Today you will learn to work with two important mechanisms: The first one is very known today as a good mechanism, and the second one is old and not used today as normal mechanism.” The mechanisms are: Deffie-Hellman key exchange and the WEP for wifi authentication (wifi is not really here). [Read More]

At first we need to check if the executable was packed with a packer of some sort. I’ll use “DetectItEasy” for this check: Nice, the executable isn’t packed! It’s now time for RE, let’s use IDA Pro. (I use the newest version - 7.0) When I try to RE something I always open the “Strings window” first, to find some helpful messages which can have xrefs for important functions. [Read More]

The Mission: This is going to be a great year! Barely five minutes into chemistry and your friend passes you this note inviting you to a party! What do they want you to bring? We easily can recognize the “Periodic Table” in the PDF file, so we combine the table with the PDF and got a list of elements Be, S, Ga, Se, Er. after some combinations we guess the string “BeErGaSeS” [Read More]

The Mission:
Decrypt me! RC3-2017{GUPNCH_AITIL}

We understand that we need to use two common ciphers, Affine and Caesar.
We brute forcing the string!

GUPNCH — affine —> GARDEN
AITIL — caesar —> SALAD

Together we got a great salad :)

The Flag:
RC3-2017{GARDEN_SALAD}