[Reverse] DSYM - Stuck on challenge

Hi all

I m stuck with this challenge i have found the price and the conversion from hex to ascii is made but i cant validate the challenge any hint or help about this string: UG****************

Type your comment> @mbouaouda said:

Hi all

I m stuck with this challenge i have found the price and the conversion from hex to ascii is made but i cant validate the challenge any hint or help about this string: UG****************

I am at the same stage as you. I think we are missing some quite obvious…

You can not retrieve the flag from the binary as cleartext, you’ll have to decrypt it in the end (the binary does not hold any information on the encryption method in question). This last part is actually a very common exercise in beginner CTFs.

Hi

Thank you yes right.
done

I can’t even start (i don’t even know what hex code op got, I see the line about price but dont know what to do after that), I tryed (cat, objdump, radare2) I guess I need to learn. But I don’t know what… Assembly? Debuggin?

Hi Everyone, completly new to Reverse Enginnering but eagar to learn. I’ve had a look at the file using radar2 and as expected most of the content makes no sense. Like most others, i’ve found the string in qurstion, however, i am struggling to see the value. A PM would be much appriciated to point me in the right direction.

Hello all,

Well, I was upset about the solution itself since I’ve got it.
Could you show me the light on the questions below:

  1. Why “some” function does not used in the binary? I mean, it is not called at all. How to get that logically, that we are interested in that exact func?
  2. What is the sense of using “that” string transformation, as far as that was not mention anywhere in the binary itself ?

Also, that questions might be as a hints :wink:

Hi all,

I’ve been stuck with this challenge for quite a while. I’m currently trying to understand the main assembly functions using ida free and also using gdb to try to the debug the program. I believe i identified some of the places where i can execute some breakpoints, but the program is not showing any data while running it.
Is there any hint that someone could give me privately to avoid spoiler?

Thanks guys!

After some many hours trying and trying, was able to get the flag :slight_smile:

Really nice challenge that teached me a lot, kudos to the creator!

I used ghidra to solve this one, by copying the function and running it on my machine to print out what I needed.
My own mistakes cost me my time to resolving this.
msg me via discord if you need help.

Hello everybody
I’m new to RevEng and I’m stuck with this challenge.
I found the string “You almost got me: D here is small pri” … with IDAPro, radare2 and Ghidra. some more information me the Ghidra date.
I also understood the “while” block but I just can’t go on.
with Ida I tried to do a Debug step by step but I couldn’t find the way to get to that SubRoutine.
someone can give me a clue … even in PM

Just done this one… once you extract the right information out of the binary you can try to get the chef to help you cook this… :smiley:

once that is done, you just need to compare what you have with what you expect and then make the necessary modifications.

I solved this, but if someone solved this with radare2 can you please help me? I’m working on learning radare2.

Unfortunately, I can’t figure out what I’m looking at or looking for… Some rudimentary hints would be great. PM me if you’re willing to help me with this. Here’s what I have figured out:

  • I can disassemble and look at strings via objdump, radare2 and gdb. The string everyone quotes is visible, but has no value afterward.
  • I can look through the code and set breakpoints, but no register ever gives me something I find relevant to the challenge.
  • The eh_frame provides additional strings, but I don’t think they’re relevant either based on the hints I see above.

I’m sure this has a simple answer, but I don’t know how to read this disassembled code in a way that guides me toward the answer.

Interesting challenge, I don’t think it’s meant to be as easy as it is.

I managed to get the string then in some way transformed it … now i got a flag it starts with HTB{****} i can understand the words inside but there are some missing letters now am confused ! … can a solver pm me so i can make sure whats the problem ?

Type your comment> @m3thr1l said:

Unfortunately, I can’t figure out what I’m looking at or looking for… Some rudimentary hints would be great. PM me if you’re willing to help me with this. Here’s what I have figured out:

  • I can disassemble and look at strings via objdump, radare2 and gdb. The string everyone quotes is visible, but has no value afterward.
  • I can look through the code and set breakpoints, but no register ever gives me something I find relevant to the challenge.
  • The eh_frame provides additional strings, but I don’t think they’re relevant either based on the hints I see above.

I’m sure this has a simple answer, but I don’t know how to read this disassembled code in a way that guides me toward the answer.

I would suggest that you go for static analysis…and read the code. If you’re having problem in reading the assembly, then you can use one of he latest reversing tool. I also noticed that IDA is shipping a decompiler in the freeware. Might try that as well. If you have any problem feel free to DM me. Although I don’t have much knowledge I’ll try my best to help you.

I’ve read through the comment, and I must be missing something extremely obvious. I’ve debugged and followed the program as best as I could, but I couldn’t even get the string to print…

I think https://cryptii.com/ is useful for this task.
I hope it isnt spoiler

Nice challenge! A little bit frustrating if you have no similar previous experience but taught me to think outside of the box and explore/manipulate the binaries in ways I didn’t think of before.