S.H.E.L.L CTF 2021: Hidden inside

Hidden inside

Category: Forensics

chal

50 points

Raj wanted to send a msg to Brad but he wanted to hide it from his wife? Can you help Brad decode it?

Note : Wrap the flag in ‘SHELL{’ & ’}‘.

file: mystic-fairy-girl-magical-dark-cgi-3840x2558-5287.jpg

Solution

I’ve found the flag in LSB of the image with zsteg. Worth mentioning is here, that the file actually isn’t jpeg but png with incorrect extension.

zsteg mystic-fairy-girl-magical-dark-cgi-3840x2558-5287.jpg
imagedata           .. file: VAX-order 68k Blit mpx/mux executable
b1,r,lsb,xy         .. text: "NarUTO_Is_hokaGE"
b1,abgr,msb,xy      .. file: PGP Secret Sub-key -
b2,r,msb,xy         .. text: "[email protected](Z}v-J"
b2,g,lsb,xy         .. text: "'vV4Mc$v)7"
b2,g,msb,xy         .. text: "zA(Z}}-J"
b3,bgr,msb,xy       .. text: "F7JNF8qb"
b3,abgr,msb,xy      .. text: "g{6G|DGt6gs"
b4,r,lsb,xy         .. text: "c$UR%R$C#5D2%E#%C#\#$C$UU#EUU%DR'C3B5'CS"
b4,r,msb,xy         .. text: "\"Ll*\"bNd**"
b4,g,lsb,xy         .. text: "tEUTET5dDEUDEUDES4C5TEUU4UUVEVdGd4TE7SS"
b4,rgb,lsb,xy       .. text: "H$eWUrF#TWF"
b4,bgr,lsb,xy       .. text: "XBd'UuVBS'T"
b4,rgba,lsb,xy      .. text: "4o$o4o4oU"

Flag

SHELL{NarUTO_Is_hokaGE}

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