1. We have a file with no format.
2. With the file AV command we understand that it is a GIF image.
3. Use exiftool -v AV.gif to read the metadata.
4. We see the base64 encoded string: dmlzaHdhQ1RGe3ByMDczYzdfdXJfM1gxRn0=.
5. Decode it and get the flag.

Flag: vishwaCTF{pr073c7_ur_3X1F}.