Problem: Files can always be changed in a secret way. Can you find the flag? cat.jpg
File: THE_FILE
Solution: Using an EXIF view you see
XMPToolkit Image::ExifTool 10.80
License cGljb0NURnt0aGVfbTN0YWRhdGFfMXNfbW9kaWZpZWR9
Rights PicoCTF
Decode cGljb0NURnt0aGVfbTN0YWRhdGFfMXNfbW9kaWZpZWR9 from base64 and you get the flag.
Flag: picoCTF{the_m3tadata_1s_modified}