Forensics & Steganography Sig21CTF IIUM

Forensics

Flag 1.

This challeng we have a png file, but when we try opening it we got an error msg Invalid filetype Inspecting the file we noticed the magic bytes didnt matched a png magic byte. we need to edit the hex and make it look like this. if we open it again now we should get the flag. sig21ctfm4g1c_by3s_4r3_0p

00000000: 8950 4e47 0d0a 1a0a 0000 000d 4948 4452  .PNG........IHDR
00000010: 0000 0193 0000 0051 0802 0000 0098 29dc  .......Q......).
00000020: 3d00 0000 0970 4859 7300 000e c400 000e  =....pHYs.......
00000030: c401 952b 0e1b 0000 135a 4944 4154 789c  ...+.....ZIDATx.
00000040: eddc e993 1ce5 7d07 f0e7 e8a7 cf39 f6d4  ......}......9..
00000050: 6ab5 9256 32b2 0e0b 8400 23cc 2dd9 2476  j..V2.....#.-.$v
00000060: b01d 235c c6b8 922a 572a 7995 37f9 6be2  ..#\...*W*y.7.k.

Steganography

Flag 1.

viewing the begining of the files looks seemingly gebrish, so i paste it to spammic hoping gives something useful. sig21CTF{40d488d2cc8a2319d9d6c70e5c45c358c085216a3d66f86b17c883d0b1cda30e}

Flag 2.

For this challenge we have a png file. simply running steghide extract -sf file.jpg give us the flag sig21CTF{i_bet_you_aint_wearing_your_mask_rn}

Thanks for reading, I hope this helps :)