Hiding files inside picture on Linux

Date: 16/10/22 - 00:33:05

Hiding your files inside picture is very old school.

Using zip/7zip/tar etc.. to compress files, can be one or two files

and then combine again with a picture. (PNG/JPEG/BMP/etc.)

Example: Hiding plain text file "database.txt".

database.txt
emel@paradox=> zip a.zip database.txt
  adding: database.txt (stored 0%)
emel@paradox=>

(!) If you want to secure your compressed file, for zip use "-e"

zip -e a.zip database.txt

Now we have a.zip

emel@paradox=> ls
a.zip  database.txt

a.zip contain database.txt

emel@paradox=> unzip -l a.zip
Archive:  a.zip
  Length      Date    Time    Name
---------  ---------- -----   ----
       12  10-16-2022 00:47   database.txt
---------                     -------
       12                     1 file

We have a picture in our current directory, the picture can be PNG, JPG, BMP, WEBP.

emel@paradox=> ls
a.zip  database.txt  rei.jpg

Combine a picture and compressed file together is very easy on Linux, just use cat command.

(!) Remember, image file must come first in the front of zip file when using cat command.

emel@paradox=> cat rei.jpg a.zip > rei_cute.jpg
emel@paradox=> ls
a.zip  database.txt  rei.jpg  rei_cute.jpg

Checking filetype.

rei.jpg doesn't contain any files, rei_cute.jpg contain one file "database.txt".

emel@paradox=> file rei_cute.jpg
rei_cute.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, baseline, 
precision 8, 500x500, components 3
emel@paradox=> file rei.jpg
rei.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, baseline, precision 8, 
500x500, components 3

Filesize.

emel@paradox=> ls -la
total 176
drwxr-xr-x  2 emel emel  4096 Oct 16 01:07 .
drwxr-xr-x 29 emel emel  4096 Oct 16 00:46 ..
-rw-r--r--  1 emel emel   214 Oct 16 00:59 a.zip
-rw-r--r--  1 emel emel    12 Oct 16 00:47 database.txt
-rw-r--r--  1 emel emel 81395 Oct 16 01:05 rei.jpg
-rw-r--r--  1 emel emel 81609 Oct 16 01:07 rei_cute.jpg

List files in rei_cute.jpg

emel@paradox=> unzip -l rei_cute.jpg
Archive:  rei_cute.jpg
warning [rei_cute.jpg]:  81395 extra bytes at beginning or within zipfile
  (attempting to process anyway)
  Length      Date    Time    Name
---------  ---------- -----   ----
       12  10-16-2022 00:47   database.txt
---------                     -------
       12                     1 file

Extracting file from rei_cute.jpg just like normal zip file.

(!) If you encrypted zip file, It will prompt you to input password to extract just like normal zip file.

emel@paradox=> unzip rei_cute.jpg
Archive:  rei_cute.jpg
warning [rei_cute.jpg]:  81395 extra bytes at beginning or within zipfile
  (attempting to process anyway)
[rei_cute.jpg] database.txt password:
 extracting: database.txt
emel@paradox=> ls
a.zip  database.txt  rei.jpg  rei_cute.jpg

I'm apologize if there's misleading or not enough information, That's all I know about it.

Thank you for reading.

♡ 2020-2022 by emelhnn, powered by unk, compatible with lynx.

Updated on Tue Oct 25 03:26:40 +07 2022 at paradox, Linux 5.15.72