Here is a file with another file hidden inside it. Can you extract it? https://mega.nz/#!qbpUTYiK!-deNdQJxsQS8bTSMxeUOtpEclCI-zpK7tbJiKV0tXYY
File: THE_FILE
Solution:
Use binwalk on the file.
Note: if you try to use binwalk -Me you will not extract all the files.
binwalk PurpleThing.jpeg -e --dd=".*"
Will extract all the files and you will get the flag in the file 25795
Flag: ABCTF{b1nw4lk_is_us3ful}