What Is Steganography & How Does It Work?

What is Steganography? It is the practice of concealing information within ordinary files or media, making the hidden data undetectable to anyone unaware of its presence. From ancient techniques like invisible ink to modern digital methods that embed messages in images, audio, or network traffic, it has evolved significantly. While it is widely used for data protection and digital watermarking, cybercriminals also exploit it to hide malware and evade detection.

In this blog, we’ll explore what steganography is, its types, techniques, and real-world applications in today’s digital landscape.

What is Steganography, and How Does It Work?

It is the art of hiding a message in a way that prevents detection. Unlike cryptography, which focuses on encrypting data to make it unreadable to unauthorized users, it hides the very existence of the message itself.

This term comes from the Greek words steganos (meaning covered or concealed) and graphein (meaning writing). The technique has ancient origins, with the Greeks using it to conceal military messages. For instance, Spartan warriors would hide messages on wooden tablets, cover them with wax, and then send them off for retrieval by the intended recipient, who would scrape off the wax to read the hidden message.

Now that we understand what it is and how it functions, let’s explore how it differs from cryptography and obfuscation, two other techniques used to secure information.

Steganography vs Cryptography vs Obfuscation

Although steganography, cryptography, and obfuscation all aim to protect data, they are distinct techniques:

• Cryptography involves converting readable data into an unreadable format using encryption keys. The focus is on making the data unreadable, not necessarily on hiding its existence.
• Steganography goes a step further by concealing the fact that a message is being transmitted. The objective is to hide the message within another file (image, text, video, etc.) in such a way that it remains undetected.
• Obfuscation refers to techniques that make data or code difficult to understand. This could involve altering code or text to prevent easy comprehension, which is often used in software development.

While steganography, cryptography, and obfuscation each serve different purposes, real-world examples help illustrate how it is actively used across various fields.

Examples of Steganography

It has evolved from simple physical methods to complex digital techniques. Here are some examples:

• Invisible Ink: It is one of the earliest forms; invisible ink can be used to write secret messages that are only visible when exposed to heat.
• Watermarking: Modern printers embed tiny, invisible codes into documents, like the Machine Identification Code (MIC), which can be used to track printed materials.
• Crossword and Sudoku Puzzles: Hidden messages can be embedded within seemingly normal puzzles, requiring specific knowledge or insight to decode.

In the digital realm, steganography has become even more sophisticated, using techniques like the Least Significant Bit (LSB) algorithm, which hides information in image, audio, or video files.

What Are the 5 Types of Steganography?

As steganography has evolved, different methods have emerged to hide information across various mediums. Let’s take a closer look at the five major types.

1. Text Steganography

It hides messages within a body of text. Simple methods include using the first letter of each sentence to spell out a hidden message. More complex techniques might involve subtle encoding within punctuation marks or spaces.

2. Image Steganography

In this, information is concealed within digital images. The Least Significant Bit (LSB) algorithm is often used, where the least significant bit of each pixel is altered to encode the hidden message. These changes are generally imperceptible to the human eye, making it an effective form.

Example: A digital photo might seem normal to the viewer, but hidden in the pixels could be a secret message or even another image.

3. Video Steganography

It works similarly to image steganography, but since videos are essentially a sequence of images, entire messages or even videos can be concealed. Each video frame can carry a hidden message, making it a more advanced technique.

Example: An attacker could embed a malicious video inside a seemingly innocuous video clip, with hidden data in each frame.

4. Audio Steganography

This involves hiding messages within sound files. One well-known method is backmasking, where a message is played backward, requiring the listener to reverse the audio to hear it. More advanced techniques manipulate the least significant bits of the audio file, just like in images.

5. Network Steganography

It hides data in network traffic, often within the headers or payloads of packets sent over the internet. It can also involve variations in packet timings, allowing data to be covertly transmitted without raising suspicion.

Example: Attackers may use network steganography to hide malware command-and-control communications within normal network activity, bypassing firewalls and intrusion detection systems.

With a clear understanding of the different types of steganography, let’s explore some of the tools and techniques used to implement these methods effectively.

Steganography Tools and Techniques

There are several tools available for those looking to explore steganography:

1. OpenStego: This open-source tool supports image file steganography, allowing users to hide data in images or watermark files.

2. OpenPuff: A more advanced tool, OpenPuff supports hiding data in audio, video, and image files. It even allows messages to be split across multiple files for added security.

3. Steghide: A steganography program that allows users to embed data within audio and image files, specifically supporting formats like JPEG, BMP, WAV, and AU. It offers encryption and compression of embedded data, enhancing security and reducing file size.

4. Xiao Steganography: A free tool that enables users to hide secret files within BMP images or WAV audio files. It supports encryption algorithms such as RC2 and Triple DES, providing an additional layer of security to the hidden data.

5. SilentEye: A cross-platform application (available for Windows and Linux) that facilitates hiding messages within images and audio files. It supports various image formats, including BMP, JPG, and PNG, as well as audio formats like WAV. SilentEye also offers encryption of the hidden data to enhance security.

While steganography can be used for legitimate purposes, it also poses a significant risk when exploited by cybercriminals. Let’s examine how malicious hackers leverage it for nefarious activities.

How Do Malicious Hackers Use Steganography?

While steganography has legitimate uses, such as securing confidential communication, it is also exploited by cybercriminals. Hackers often use it to hide malicious code within seemingly harmless files. For instance, a web skimmer can be concealed within the EXIF metadata of an image, enabling it to capture sensitive user data on e-commerce sites without being detected.

In one case, researchers discovered that attackers hid malware code in the metadata of a seemingly innocent image, which was then executed upon viewing the image, compromising the users’ personal information.

Conclusion

​Steganography, the art of concealing information within other non-secret data, has a rich history and continues to play a significant role in modern digital communication. Throughout this blog, we’ve explored its various forms, techniques, and applications, highlighting both its legitimate uses and potential for misuse. As technology advances, understanding it becomes increasingly crucial for both protecting sensitive information and recognizing its potential threats in the cybersecurity landscape.

For those eager to deepen their cybersecurity expertise, Edureka’s Cyber Security Training Course offers hands-on experience in key areas such as IAM, network security, and cryptography, preparing you for in-demand roles at top companies.

FAQs

1. What is the application of steganography?

It is used in various fields such as cybersecurity, digital watermarking, and protecting intellectual property. It allows individuals or organizations to hide sensitive data within seemingly innocuous files.

2. What is steganography and its techniques?

It  is the practice of hiding a secret message within a non-secret medium, like an image, text, or audio file. Common techniques include Least Significant Bit (LSB) in images, backmasking in audio, and encoding hidden messages within video frames.

3. How many types of steganography are there?

There are five main types are: text, image, video, audio, and network.