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praseodym/openctf2018_8.md

Created August 12, 2018 18:34
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OpenCTF 2018: Challenge 8 (yodawg.jpg)
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openctf2018_8.md

OpenCTF 2018: Challenge 8 (yodawg.jpg)

Challenge text:

yodawg.jpg 50 ---
steghide was found on the hackers computer.  https://scoreboard.openctf.com/yodawg.jpg-a5f90bcb58c65886c8b40623ad5bf73ae62545bc

This file is a tar.gz containing yodawg.jpg. From the hint we know that the steghide tool was used hide another file in this jpg. steghide needs a passphrase; the jpg file happens to represent the flag of Gabon and Gabon was indeed the passphrase used to hide the data:

$ steghide extract -sf yodawg.jpg
Enter passphrase: Gabon
wrote extracted data to "IHeardYouLikeFlags.jpg".

It turns out that IHeardYouLikeFlags.jpg contains another steghided-file, which we can extract using an empy passphrase:

$ steghide extract -sf IHeardYouLikeFlags.jpg 
Enter passphrase: 
wrote extracted data to "so.txt".
$ cat so.txt
I_put_this_as_the_flag_in_a_flag_so_that_you_can_flag_the_flag.

And the flag was indeed I_put_this_as_the_flag_in_a_flag_so_that_you_can_flag_the_flag..

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