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}.