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What is Code Obfuscation in Cyber Security and how it works?

Code obfuscation alters the initial code so a hacker can't read it, but the code remains functioning. Use many code obfuscation techniques for layered security.

What is code obfuscation?

What is Code Obfuscation?

To obfuscate a code means to make it hard for the reader to understand. It is a common way to protect intellectual property, like the source code, in programming. The main goal of code obfuscation is to make it as hard as possible for the other side to reverse engineer. If an unauthorized person knows how an application works, this is a security risk.

Security threats include a wide range of harmful actions, such as changing the code, taking advantage of a weakness, or getting data out of the system. These are all common parts of a reverse engineering attack. Hackers can use reverse engineering to copy the look and feel of an app, repackage it, and put it on third-party app stores, where it can harm users who download it without knowing it.

Code obfuscation is another way that hackers get around antivirus protection and get unauthorized access. The same way that a good mobile app developer would use code obfuscation to make their app more secure, hackers use it to hide malware and avoid being found.

Why Do Code Obfuscation Is Required?

Code obfuscation is especially helpful for open-source applications, whose code is very easy to break into for personal gain. By making it hard to figure out how an application works, developers protect the intellectual property of their products from security threats, unauthorized access, and the discovery of application flaws. This process makes it harder for bad people to get to the source code, and depending on the type of obfuscation technique used, it protects the code in different ways. Since the decompiled code can’t be understood, time, money, and resources all point toward giving up on the code when it is obfuscated.

What is Code Obfuscation

How Does Code Obfuscation Work?

A method of obfuscating a code is to encrypt it partially or completely. One way to hide information is to remove metadata from the code that gives more context and explains how the application works. Another way to hide code is to change the names of classes and variables into random labels and fill the application script with code that doesn’t do anything. Code obfuscation is the process of using any method that makes the code hard to read.

By using multiple code obfuscation techniques, you make the application more secure and stop attacks that try to figure out how it works.

Using redundant logic and code that doesn’t do anything for the application distracts the reader and makes it hard to figure out which parts of the code are important to their cause. This is called a “reverse engineering attack.”

Types of Code Obfuscation Techniques

Code obfuscation is made up of many different techniques that can work together to make a strong defense with multiple layers. It works best with languages like Java or.NET languages like C#, VB.NET, Managed C++, F#, etc. that create some kind of intermediate level instructions. Some common techniques for obfuscation and application security are:

Rename Obfuscation

Methods and variables get new names when you rename them. It makes it harder for a person to understand the decompiled source code, but it doesn’t change how the program runs. The new names can use different patterns, like “a,” “b,” and “c,” or numbers, characters that can’t be printed, or characters that can’t be seen. And you can have too many names as long as they all mean different things. Most obfuscators for.NET (C#, etc.), iOS, Java, and Android use name obfuscation as a basic change.



When a hacker wants to copy or fake your app, steal your data, or change the way a key piece of infrastructure software works, they will almost always start by using reverse engineering and a debugger to step through your app. An obfuscator can add a layer of self-protection to an application by injecting code that checks to see if it is running in a debugger. If a debugger is used, it can change sensitive data so it can’t be stolen, cause random crashes (so it looks like the crash was caused by a debug check), or do anything else the user wants. It could also send a warning signal to a service by sending a message.

String Encrypting

All strings are easy to find and read in an executable that has been managed. Even if the names of methods and variables change, strings can still be used to find important parts of code by looking for string references inside the binary. This includes any messages that are shown to the user, especially error messages. String encryption hides strings in the executable and only brings back their original value when it’s needed to protect against this kind of attack. When decrypting strings at runtime, there is usually a small performance hit.



An obfuscator can add application self-protection to your code so you can check that your app hasn’t been changed in any way. If tampering is found, it can shut down the app, limit what it can do, make it crash randomly (to hide why it crashed), or do anything else the user wants. It could also send a message to a service with information about the tampering that was found.

Insertion of Dummy Code

Adding code to the executable that doesn’t change the way the program works but breaks decompiles or makes it much harder to understand code that has been reverse engineered.

Opaque Predicate Insertion

Adds conditional branches that always evaluate to known results, which are hard to figure out with static analysis. This is a way to add potentially wrong code that will never be run, but will confuse attackers who are trying to figure out what decompiled output means.


Control Flow Code Obfuscation

Control flow obfuscation combines conditional, branching, and iterative constructs to make valid logic that can be run, but when the code is decompiled, the results are not predictable in terms of their meaning. Simply put, it makes code that has been decompiled look like spaghetti logic, which is hard for a hacker to understand. These techniques could affect how well a method works when it’s being used.

Control-Flow-Code-ObfuscationChanges in Instruction Patterns

Changes the way the compiler makes common instructions into other, less obvious structures. These are perfectly legal instructions in machine language, but they might not translate well to high-level languages like Java or C#. One example is transient variable caching, which takes advantage of the fact that Java and.NET runtimes are based on stacks.


Get rid of unused code and metadata

By taking out debug information, metadata that isn’t necessary, and code that isn’t being used, you can make an application smaller and give an attacker less information. This step may slightly improve how well the program runs.

Binary Linking/Merging

This transformation turns more than one executable or library into one or more binaries. Linking can make your app smaller, especially when combined with renaming and pruning. It can also make deployment easier, and hackers may not be able to get as much information.

Arithmetic Obfuscation

The process of obfuscating code with arithmetic involves exchanging straightforward arithmetic and logical components with their more convoluted versions.

Custom Encoding

This method of obfuscating code encrypts strings using a unique algorithm, as suggested by its name. This makes it possible for a decoder function to recover the code that was encrypted in the first place.

Code Transposition

This method of obfuscating code involves randomly shuffling the routines and branches contained within the code, but it does not have an effect on how the code is executed. It is widely used by malware developers as a means of evading detection by antivirus software.

Code Virtualization

Code virtualization, often known as virtualization obfuscation, is a way of safeguarding software against malicious code analysis that falls under the category of code obfuscation. It does this by exchanging the code found in a binary for a bytecode that is semantically equivalent to the original code. A virtual machine is the only thing that can interpret the bytecode properly. This makes it a difficult and time-consuming task for the attacker to divulge the final code.

How to Assess the Quality of Code Obfuscation

Consider the following criteria in order to evaluate the efficacy of the code obfuscation and establish its level of quality:


This aspect displays the degree to which the original code is distinct from the code after it has been obfuscated. Examining the breadth of the inheritance tree is another common method for calculating the differentiation index, although counting the number of predicates introduced into the obfuscated code can also be used. The better off one is, the greater the DIT.


The application of automatic DE obfuscation techniques is the most effective method for determining the level of success achieved by obfuscation measures that have been put into place. The obfuscation of the code is said to be stronger when it requires a greater amount of resources, time, and effort to revert the code back to its initial state.


In order to calculate the cost of your obfuscation efforts, you will need to do a comparison between the amount of time and resources required to execute the obfuscated code and the amount of time and resources required to run the code in its original form. The greatest outcomes for obfuscation are typically not the most expensive ones, but rather the ones that take a reasonable number of resources for an appropriate amount of protection. This is because these methods are more likely to be successful.


When one considers the many different techniques for obfuscating code that were covered in the prior chapters, it becomes clear that it would be beneficial to combine more than one of these strategies. The complexity and quality of the obfuscation efforts that are implemented are both increased by this layered approach.


The degree to which the converted code is more obfuscated than the original is referred to as its potency. Measures of software complexity can include things like the number of predicates it possesses, the depth of its inheritance tree, the number of nesting levels, and many more. These measures are defined by software complexity metrics. Obfuscation is done with the intention of increasing complexity while the objective of excellent software design is to reduce it as much as possible based on these characteristics.


Obfuscated code is considered to be of the highest quality when it gives the appearance of having none at all. On the other hand, the obfuscated version shouldn’t be any different from the original in any way. The attacker is confronted with procedures and logic that are difficult to follow, which slows down their progress in reverse engineering.

Advantages of using code obfuscation

1. The code still works the way it should

Even though the code is written differently, all of the functions from the original source code for the mobile app are still there. The application still looks and feels the same, and its security has been tightened.

2. Prevention of Copied Apps

One of the most common reasons for reverse engineering is copying stolen code and putting it into a fake app to sell it on third-party app stores. Users who don’t know better download these fake apps and give away their personal and financial information. Code obfuscation works well to stop these kinds of attempts.

3. Integrated Application Self-Protection

The main purpose of obfuscating code is to stop attacks like reverse engineering. Obfuscation software makes the code unreadable, which discourages hackers from getting any further with their bad plans. It also protects the mobile app from the inside by warning the app’s stakeholders about a possible security threat.

4. Code Optimization

Some ways to hide code are based on removing metadata or code that doesn’t do anything useful. This can make the application smaller and the code run faster.

5. Safeguarding Intellectual Property

Code obfuscation is a form of intellectual property protection that can help organizations and application stakeholders protect their code from attackers and competitors. The attackers have done this before to keep information about security flaws from getting out to big companies.

Disadvantages of Code Obfuscation

Cybercriminals also use obfuscation to hide what they do. Let’s figure out how to stay safe from them.

Malware writers often use obfuscation to avoid being found by antivirus scanners. It is important to look at how these ways of hiding information are used in malware.

All methods of hiding code have some effect on how well it works, even if it’s only a small one. Depending on how much code was hidden and how complicated the hidden methods were, deobfuscating the code could take a long time.

Most automatic obfuscators can decode a program that has been obfuscated. Obfuscation makes it harder to figure out how something works, but it doesn’t stop it. Some anti-virus software will warn users if they visit a website with obfuscated code, because obfuscation can be used to hide malicious code. This could stop people from using real apps and turn them away from businesses they can trust.


Code obfuscation alone won’t stop complicated security threats. With automated tools and hackers’ expertise, it’s possible to reverse-engineer obfuscated code.

Code obfuscation isn’t a panacea for application security. Depending on security necessity, application type, and performance benchmark, the dev team may employ code obfuscation techniques to secure their code in an untrusted environment. Each technique should be evaluated. This method should complement encryption, RASP, data retention policies, etc.


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