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Cryptic Profile

Description of the challenge​

  • CTF Name : Hackday 2026
  • Category : OSINT
  • Difficulty : Insane
  • Date : 23-25 January 2026

We are given the following challenge:

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The starting point​

The challenge provides us with an username : Huf48500. A quick search on Google with this username leads us to a post on StackOverflow where the user has asked a question about web development : link

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In the code block, we can see a link to a GitHub username :

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We can see that the GitHub has no repositories, but there is a link to his Facebook profile :

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On the Facebook, we can a single post. At first, we can't see any references to blockchain. However, by opening the only post and the dev tools, we can see an interesting string in the alt attribute of the image : 0x12154e064d46FDd888C768A0f919c8d177714C39 ETH thanks for the donation :)

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Pivoting to the blockchain​

Thus, we can check this address on Etherscan : link

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We got one part of the flag : the Block number 14034531. Then, we needed to get the date of expiration of the sender domain hacker-man.eth. To do so, I used the website ENS Domains to look for the domain and found the expiration date : 2031-12-05.

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FLAG

HACKDAY{14034531_2031-12-05}