⚡️ Stegseek

Stegseek is a lightning fast steghide cracker that can be used to extract hidden data from files. It is built as a fork of the original steghide project and, as a result, it is thousands of times faster than other crackers and can run through the entirety of rockyou.txt* in under 2 seconds.

Stegseek can also be used to extract steghide metadata without a password, which can be used to test whether a file contains steghide data.

* rockyou.txt is a well-known password list with over 14 million passwords.

Demo: random rockyou.txt password (in real time)

Skip ahead to Performance for some raw numbers.

🔧 Installation

The following instructions walk you through the installation process. Alternatively, you can run Stegseek in a Docker container. Skip ahead to Docker for instructions.

Releases

Linux

On Ubuntu and other Debian-based systems, you can use the provided .deb package for installation:

1. Download the latest Stegseek release
2. Install the .deb file using sudo apt install ./stegseek_0.5-1.deb

On other systems you will have to build Stegseek yourself. See BUILD.md for more information.

Windows

Building Stegseek as a native Windows app is sadly not supported. Instead you should run Stegseek using WSL. The Ubuntu WSL distribution is recommended for optimal compatibility.
Once you have configured WSL, Stegseek can be installed using the above Linux instructions.

By default, WSL mounts the C:\ drive at /mnt/c/, which you can use to easily access your files.

▶️ Using Stegseek

Cracking

The most important feature of stegseek is wordlist cracking:

stegseek [stegofile.jpg] [wordlist.txt]

This mode will simply try all passwords in the provided wordlist against the provided stegofile.

Detection and passwordless extraction

Stegseek can also be used to detect and extract any unencrypted (meta) data from a steghide image. This exploits the fact that the random number generator used in steghide only has 2^32 possible seeds, which can be bruteforced in a matter of minutes.

stegseek --seed [stegofile.jpg]

This command will tell you:

• Whether this file actually contains steghide content.
• How much hidden content the file contains.
• How the content was encrypted .

If you're (very) lucky and the file was encoded without encryption, this mode will even recover the encoded file for you!

The below demo features a challenge from X-MAS CTF 2020. A flag was hidden using a secure random password, but without encryption enabled. Within a few minutes, Stegseek is able to recover the embedded file without needing to guess the correct password.

Available arguments

Use stegseek --help to get the full list of available options:

StegSeek version 0.5

=== StegSeek Help ===
To crack a stegofile:
stegseek [stegofile.jpg] [wordlist.txt]

Commands:
 --crack                 Crack a stego file using a wordlist. This is the default mode.
 --seed                  Crack a stego file by attempting all embedding patterns.
                         This mode can be used to detect a file encoded by steghide.
                         In case the file was encoded without encryption, this mode will
                         even recover the embedded file.
Positional arguments:
 --crack [stegofile.jpg] [wordlist.txt] [output.txt]
 --seed  [stegofile.jpg] [output.txt]

Keyword arguments:
 -sf, --stegofile        select stego file
 -wl, --wordlist         select the wordlist file
 -xf, --extractfile      select file name for extracted data
 -t, --threads           set the number of threads. Defaults to the number of cores.
 -f, --force             overwrite existing files
 -v, --verbose           display detailed information
 -q, --quiet             hide performance metrics (can improve performance)
 -s, --skipdefault       don't add guesses to the wordlist (empty password, filename, ...)

Use "stegseek --help -v" to include steghide's help.

Steghide

Stegseek includes nearly all of steghide's functionality, so it can also be used to embed or extract data as normal. The only catch is that commands must use the --command format.
So steghide embed [...] becomes stegseek --embed [...] .

🐳 Docker

You can also run Stegseek as Docker container:

docker run --rm -it -v "$(pwd):/steg" rickdejager/stegseek [stegofile.jpg] [wordlist.txt]

This does require that the wordlist and stegofile are located in current working directory, as that folder is mounted to /steg inside of the container.

📈 Performance

This is where Stegseek really shines. As promised, let's start with the "rockyou.txt in just 2 seconds" claim.
All of these numbers are measured on a laptop with an Intel i7-7700HQ CPU @ 2.80GHz and 8 GB of RAM.

RockYou.txt

I picked the last password in rockyou.txt without control characters: "␣␣␣␣␣␣␣1" (7 spaces followed by '1').
This password is on line 14344383 out of 14344391

> time stegseek 7spaces1.jpg rockyou.txt
StegSeek version 0.5
Progress: 95.21% (133213740 bytes)           

[i] --> Found passphrase: "       1"
[i] Original filename: "secret.txt"
[i] Extracting to "7spaces1.jpg.out"

real	0m1,644s
user	0m12,847s
sys	0m0,041s

And there it is, over 14 million passwords in less than 2 seconds 😍.

How does this compare to other tools?

To test the performance of of other tools, I created several stego files with different passwords, taken from rockyou.txt. I ran each of the tools with their default settings, except Stegbrute where I increased threading for a fair comparison.

[p] = projected time based on previous results.

[0.022s, 0.022s, 0.022s, 0.022s, 1.45s]

To compare the speed of each tool, let's look at the last row of the table (otherwise Stegseek finishes before all threads have started).

At this scale Stegseek is over 12 000 times faster than Stegcracker and over 7000 times faster than Stegbrute.

📓 Changelog

v0.5

2020-12-28
improvements:

• Uses way less memory (memory usage is no longer tied to Wordlist length)
• Wordlist is loaded on the fly, so we can start cracking immediately.
• Fixed high false positive rate on --seed

[email protected]:~/testfiles# time stegseek 7spaces1.jpg rockyou.txt -q
Stegseek version 0.5
[i] --> Found passphrase: "       1"
[i] Extracting to "7spaces1.jpg.out"

real	0m0.837s
user	0m12.694s
sys	0m0.052s

> steghide --embed -sf steg.jpg -ef secret.txt -cf clear.jpg -f -p $(shuf -n 1 realuniq.lst)
embedding "secret.txt" in "clear.jpg"... done
writing stego file "steg.jpg"... done
> time stegseek steg.jpg realuniq.lst -
StegSeek version 0.5
Progress: 97.83% (15354873129 bytes)           

[i] --> Found passphrase: "Hossuungsstrahl"
[i] Original filename: "secret.txt"
[i] Extracting to stdout

Now that I can stream in the file on the fly, 
I can run the cracker with stupidly large 
wordlists. This one is 15 GB!

real	3m25,540s
user	23m13,614s
sys	0m10,260s

v0.4

2020-12-01
improvements:

• Added seed cracking to allow for passwordless data extraction
• Overhauled parser to allow for positional arguments
• cracks rockyou.txt in 2 seconds

v0.4.1

2020-12-23
Fixed a bug where stegseek would fail to find a password on rare occasions.

v0.3

2020-11-08
improvements:

• Made threading lock-free s.t. multiple threads are used more efficiently
• Added -xf argument to --crack, used to specify the location of the extracted file
• Made the .deb package compatible with Debian/Kali
• cracks rockyou.txt in 4 seconds

v0.2

2020-11-05
improvements:

• Give up on a passphrase once a single bit of the magic fails to decode
• Removed costly BitString / EmbData allocations
• Improved performance of the selector
• cracks rockyou.txt in 5 seconds.

v0.1

2020-11-04
Initial release, features:

• Only loads the stego file once, unlike conventional crackers
• Workpool based threading
• Attempts to crack the first 3 bytes first, before attempting full decryption
• Added .deb package and docker container
• cracks rockyou.txt in 41 seconds.