information

Problem

Files can always be changed in a secret way. Can you find the flag? cat.jpg

• cat.jpg

• Source

Solution

1. Download the image and use exiftool cat.jpg. The license field looks suspicious:

   ExifTool Version Number         : 12.16
   File Name                       : cat.jpg
   Directory                       : .
   File Size                       : 858 KiB
   File Modification Date/Time     : 2021:03:15 14:24:46-04:00
   File Access Date/Time           : 2021:03:16 15:08:38-04:00
   File Inode Change Date/Time     : 2021:03:16 15:08:32-04:00
   File Permissions                : rw-r--r--
   File Type                       : JPEG
   File Type Extension             : jpg
   MIME Type                       : image/jpeg
   JFIF Version                    : 1.02
   Resolution Unit                 : None
   X Resolution                    : 1
   Y Resolution                    : 1
   Current IPTC Digest             : 7a78f3d9cfb1ce42ab5a3aa30573d617
   Copyright Notice                : PicoCTF
   Application Record Version      : 4
   XMP Toolkit                     : Image::ExifTool 10.80
   License                         : cGljb0NURnt0aGVfbTN0YWRhdGFfMXNfbW9kaWZpZWR9
   Rights                          : PicoCTF
   Image Width                     : 2560
   Image Height                    : 1598
   Encoding Process                : Baseline DCT, Huffman coding
   Bits Per Sample                 : 8
   Color Components                : 3
   Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
   Image Size                      : 2560x1598
   Megapixels                      : 4.1

2. We can decode this string using CyberChef. Paste in the string and drag in the magic block into the recipe.

Flag

picoCTF{the_m3tadata_1s_modified}