[Reversing] Bypass

I create the post to collect all the ideas about the challenge. obviously without giving spoilers

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Comments

  • Pretty cool challenge, learned some new tricks. What I did wasn't reversing per se, but it should be possible.

    clubby789

    • GCIH
      If you need help with something, PM me how far you've got already, what you've tried etc (I won't respond to profile comments, or on box release night). And remember to +respect me if I helped you ; )
  • Nice challenge. I used a disassembler and some breakpoints to get the flag.. But i don't undestand how i could get the flag with static analysis. Someone could pm me?

  • If someone finds a way to get the flag with static analysis PM me.
    I created the Challange and it was meant to use a Debuger like Dnspy :)

    Baikuya
    OSCP

  • This was a very simple challenge and basic practice for newcomers in re. i quite like this, kudos Baikuya!

  • Type your comment> @Baikuya said:

    If someone finds a way to get the flag with static analysis PM me.
    I created the Challange and it was meant to use a Debuger like Dnspy :)

    That's a huge spoiler in itself

  • Type your comment> @unsux said:

    This was a very simple challenge and basic practice for newcomers in re. i quite like this, kudos Baikuya!

    Thank you very much

    @dosxuz said:
    Type your comment> @Baikuya said:

    If someone finds a way to get the flag with static analysis PM me.
    I created the Challange and it was meant to use a Debuger like Dnspy :)

    That's a huge spoiler in itself

    Well I dont think so. If you read the challange description you can see that you must bypass something....

    Baikuya
    OSCP

  • It took me longer to clone and build dnSpy than to do the bypass 😁.
    Great tool!! Thanks

    Hack The Box

  • First time using dnSPY. I had difficulties recompiling the code but found a work around. Overall cool simple challenge. PM for nudge

    GotRoot
    If I helped you out at all, feel free to click my badge and give +1 respect!

  • This challenge was really fun for a complete noob like me. Thanks @Baikuya!

    It ain't much, but it's honest work
    sparrow1

  • Your welcome :)

    Baikuya
    OSCP

  • Cool challenge, I first tried the other spy, but the obfuscation was "unbreakable" :-). Learned something new.

    k4wld

  • Type your comment> @Baikuya said:

    If someone finds a way to get the flag with static analysis PM me.
    I created the Challange and it was meant to use a Debuger like Dnspy :)

    I did in fact complete the challenge via static analysis. I'll PM you.

  • This was fun. I didn't know much about .NET and reversing it, nor did I know much about the tools to do it, so this was a very nice way to get to know them both.

  • If anyone could PM me and help me with this I'd much appreciate it. This is my first time reversing and I can understand the code, but I can't seem to figure out certain components.

  • edited April 8

    Type your comment> @pythonier5001 said:

    If anyone could PM me and help me with this I'd much appreciate it. This is my first time reversing and I can understand the code, but I can't seem to figure out certain components.

    I really need the help as well.

    EDIT: Actually this was easy, and very nice. This was my first RE challenge. Feel free to DM me if you need help.

  • I'm a very beginner in CTFs so I'm with some difficulty to solve it. I was trying to hack the .exe file through radare2, but it was so difficult. So I read here that you guys were using something like dnSpy, but I'm in Linux and I can't install it. Is there some tool similar to dnSpy to Linux? I saw on the internet a guy that solved this problem using OllyDbg as well, but I'm trying to use it with wine and when I run the Bypass.exe OllyDbg crash. An alternative to OllyDbg in Linux is the edb-debugger, but when the program print "Enter a username:" edb-debugger crash too.

  • Its easy with basic reverse and basic logic

  • Type your comment> @Baikuya said:

    If someone finds a way to get the flag with static analysis PM me.
    I created the Challange and it was meant to use a Debuger like Dnspy :)

    @Baikuya why create a challenge that requires a specific tool to solve? Just curious. I am using IDA disassembler to solve it and it's not working. It says processor 'cli' is not included. So I have to install and use a tool like Dnspy. This is why I am curious.

  • Type your comment> @Baikuya said:

    If someone finds a way to get the flag with static analysis PM me.
    I created the Challange and it was meant to use a Debuger like Dnspy :)

    I use kali linux and I am running dnSpy with wine. In dnSpy, I am getting an error:
    Could not start the debugger. Make sure you have access to Bypass.exe Error: Couldn't find the CLR dll file
    Can you help?

  • Struggling with the Decompiler, dnSpy, usage. I have found the logic to bypass but could not edit the decompiled code.
    Any kind of help related to dnSpy would be appretiated.

  • I'm in the same boat, can't edit the code. :( New to dnspy
  • Just did it.

    No need to edit anything in the code. Just play with the code using Local Variables.

  • Type your comment> @IR0nIVI4n said:

    Type your comment> @Baikuya said:

    If someone finds a way to get the flag with static analysis PM me.
    I created the Challange and it was meant to use a Debuger like Dnspy :)

    @Baikuya why create a challenge that requires a specific tool to solve? Just curious. I am using IDA disassembler to solve it and it's not working. It says processor 'cli' is not included. So I have to install and use a tool like Dnspy. This is why I am curious.

    There are other debuger as well. I just like using Dnspy cause I'am used to it :)

    Baikuya
    OSCP

  • If someone is stuck you can DM me :)

    Baikuya
    OSCP

  • Basic but high quality, makes me learned something about IL

  • am stuck a little i see some cipher generator but am not sure what the result is am i in the right track ?

  • Great work @Baikuya ! A simply but intereresting challenge.

    Thanks again! ;)

  • Type your comment> @Civero said:

    Great work @Baikuya ! A simply but intereresting challenge.

    Thanks again! ;)

    Thanks :)

    Baikuya
    OSCP

  • Once I figured out how dnSpy works, I rather quickly obtained the flag. This challenge is probably very good to get an introduction into using dnSpy. Was kinda cool. Thanks @Baikuya

    Sadly I was not able to get the flag the static way yet. Would anyone like to give me a hint on how to do so via DM?

    Ty.

  • great challenge learned a lot about using dnSpy

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