Much Ebola

I've been working with the crypto challenge "Ebola" for some time and i'd like to know if i'm going in the right direction...
Is it anything related to RSA (since thats been my main focus)?
Any tips/hints are also welcome :)



  • Think on this challenge as a 20-30 point challenge. Forget RSA it's much easier (try to crack it without the key).

  • Thank you! You just saved me allot of work =D

  • edited January 2018

    So I've pretty much decrypted the whole message (using the technique suggested here: but I haven't been able to decrypt a couple of the remaining chars... and these happen to be part of the flag :anguished: . Does anyone have any suggestions, because I really dont feel like trying out the 12 possible flags on the challenge page :D

  • If you have decrypted most of the msg perhaps use that to figure out how it was encrypted.


  • Yup. You can easily infer the rest (they cannot be what you already have ;) )

  • I must clearly be overthinking this because i can't seem to figure out how the message is (d)encrypted... a small clue would be really appreciated :)

  • nv guys... i made it... thanks allot and have a good weekend :)

  • Could I get another hint? :sweat_smile: :

  • Hello there ! If someone's available, I just need a little hint on Ebola, thought I found the cipher but the decrypted values I got made no sense.

  • can someone give me a hint for this challenge pls ? tks in advance

  • I understand how the crypto works and I have the flag (which is/could/should clearly a correct flag), but it fails when I submit it. Anyone who already completed Ebola willing to check my flag? (PM)

  • @Telduivel said:
    I understand how the crypto works and I have the flag (which is/could/should clearly a correct flag), but it fails when I submit it. Anyone who already completed Ebola willing to check my flag? (PM)

    Same situation as you. Can anyone check my flag? Please (PM)


  • Anyone willing to PM me about this? I need a little help understanding a couple of the fundamentals.


  • I decided to try this by solving it in intended way but I got stuck after getting the 1s and 0s of the key.txt. I am also not sure where to start if I go to Frequency Analysis path because if I use strings command to get the content of the file, there bunch of question marks, and if I use cat command I will get box icons with question marks.

  • I got it already before the previous year ends. Now, the question is about key.txt.

  • Solved. There are indeed two ways to solve it. @h3iron is right that this challenge can be considered a 20-30 point challenge. Interesting challenge overall.

  • I feel like im going in circles here...tried decrypting the key with an algo i found and got garbage...tried to analyze hex in the binary got nothing, same with characters...if anyone could give me a small nudge on which way to start or at least a tool to use would be really appreciated. I feel like i've had a thousand false starts

  • I have been working on this ebola virus since two days,but cannot find a good start...any suggestions will be appreciated and thanks in advance

  • Things you need to solve:
    1. Notepad++
    2. Frequency analyzer
    3. Brain(for guessing)

  • ^^ This comment :+1: Almost have it done and can only confirm that it is all you need.

    I am wondering what is the intended (or the second) way is...

    If my comment somehow helped you, you can show your appreciation with a Respect :)

  • edited April 19

    I have solved it, but I do not know what the another method is. If somebody done it using the different approach, can that somebody send me a PM? Thank you in advance.

  • If it hadn't been for this forum, I would never have guessed to look for that...
    Interesting challenge for sure! This is where I would put my "feel free to PM", but honestly, there's just not much more to say. Just do frequency analysis.

    Hack The Box

    GitHub repository with writeups:

  • Just solved this challenge using key.

    • There is two ways to solve this challenge
    • Both approaches require analyzing files content in order to know what you actually got
    • Frequency does a main role in both approaches
    • Using key to decrypt message is way faster and headacheless :)

    If you're still lost feel free to send me a PM ;)

  • So I solved it both ways. First without the key and then with the key. In my opinion, using the key is so much cleaner and removes a lot of guessing as well as trial and error.

    The hardest part about the key approach is knowing how it is encoded. Hint: the encoding of the key has to do with biology.

  • I have the flag but it's not acceptable can anyone check it for me


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