Steganography
Cyber Security Camp, July 22, 2015
Rodrigo Sardiñas
Dr. David Umphress
William Frazier
What is Steganography
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What is Steganography
• The art of covered or hidden writing.
• Steganos – Greek word meaning “covered”
• Graphy – Latin word meaning “writing” or
“drawing”
• Thousands of years old
– Tattoos, symbols, contextual clues/jargon, bunnies
• Difficult to detect (if you don’t know its there)
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What Steganography is Not
• Cryptography
– Kryptos = secret or hidden
– Graphein/Logia = writing/study
– The art of writing or solving codes.
– Hide the meaning, not the message
• Steganography
– Hide the message, not the meaning
• Can both be used to obscure data
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Example 1
• Covered or concealment ciphers
– Use null cipher to hide message according
to some prearranged set of rules
Frank is not doing my editing.
Hidden message: “Find me”
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Activity 1
• At your table, devise your own concealment
cipher strategy. (5 minutes)
• Use that strategy to hide a message. (3 min)
• Class will have several minutes to try to
decipher each group’s message.
– Prize for group with most correct guesses
– Prize for group with most elaborate or creative
strategy
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Types of Steganography
Insertion
Substitution
Generation
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Insertion (Injection)
• Hide data in sections of a file that are not
processed
– Comments section in HTML file
– After EOF marker in regular file
– Metadata section of file
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No modification of relevant data
Will add to original file size
No limit to how much can be hidden
Potential to detect if compared to original
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Example 2
Steganography via injection
Original
Edited in Notepad++
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Activity 2 (text only)
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Open an image using notepad++
Write a message at the bottom of the file
Open the image normally to view it
Experiment with writing messages at various
locations in the image (in notepad++) to see what
happens
• Discuss results of inserting messages in places
other than at the end
– What happens when you add text to beginning?
– What about somewhere in the middle?
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Activity 3 (files)
• Create file(s) (any files, text, word, etc…)
• Zip files up using built-in windows zip command
(send to -> zip file)
• Place zip and an image in same folder
• Open command in current directory
– Shift + right click -> open command prompt here
• copy /b [name of picture].jpg + [name of zip file].zip
[new name for picture].jpg
• View new image normally
• Change file extension to .zip to view archive contents
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Substitution
• Make minor changes in data such that
user doesn’t notice change
• No change in file size
• Limited in how much can be hidden
• Potential to detect if compared to
original
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Example 3
Least Significant Bit Substitution
Original
Modified
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Activity 5
• Open a web browser and go to the following URL:
– http://www.mobilefish.com/services/steganography/ste
ganography.php
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Follow instructions to upload any image
Type hidden message
Do not enter a password (no encryption)
Download image with message inside
Open in notepad++ to see if you can find message
Go back to website and follow instructions to
show message
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End of Session 1
Lunch
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Generation
• Create new file from carrier (file hiding the data)
and hidden data file using some algorithm
• No limit to how much can be hidden
• Cannot be compared to original since a brand
new “original” file is created
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Example 5
Use custom algorithm to hide data
Created image
Message hidden in
audio generated from
image
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Activity 4 Do Together (part 1)
• Use Gimp to create
hidden message
– Create new image
– Change background
color
to black
– Create text in image
(use white text)
– Export image as JPEG
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Activity 4 Do Together (part 2)
• Use coagula to convert JPEG to audio (.wav) file
– Open JPEG in coagula
– Select “render without blue”
• This should create coagula.wav in current folder
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Activity 4 Do Together (part 3)
• Use Audacity to view message
– Open coagula.wav in audacity
– Select Spectrogram option to view hidden message
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Activity 5 (part 1)
• Use OpenPuff to Hide, encrypt, and distract
• Hide data
– Choose 3 different passwords (write them down)
• 2 for crypto, 1 for scrambling
– Select data to hide
• From secret data folder
– Select multiple carriers (.mp3, .jpg, .pdf, ect…)
• From carrier folder
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Sort carriers
Select noise level
Add Decoy
Enter 3 different passwords
Choose output folder(s)
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Activity 5 (part 2)
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Activity 5 (part 3)
• Use OpenPuff to Hide, encrypt, and distract
• Unhide data
– Enter all passwords
• If you want to unhide decoy, enter decoy passwords
• If you want to unhide data, enter data passwords
– Browse to folder with previous carriers and choose
correct ones
– Sort carriers in same order as before
– Select same noise level as before
– Verify data is correct
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Activity 5 (part 4)
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Who Uses Steganography
• Spies and terrorists
– http://www.washingtonpost.com/wpdyn/content/article/2010/06/30/AR2010063003108.html
• Commercial and Government
– Suggest to use with encryption
– Watermarking
• Hackers
– http://www.tripwire.com/state-of-security/incidentdetection/hackers-exfiltrating-data-with-videosteganography-via-cloud-video-services/
• All of us after this workshop!
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Interesting Application of
Steganography
• https://danbowen.wordpress.com/2014/02/11/meet
-the-man-who-solved-the-mysterious-cicada-3301puzzle/
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A Keystone in Building a Better Future for All
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