Simple polymorphic virus written in Python for the "Malware analysis and Design" Master course in University of Verona I have included two different decryption functions below, both generated by our engine from the same input data. This is the stark reality of the threat the polymorphic virus poses to your computer systems and personal data. Just like regular encrypted viruses, a polymorphic virus infects files with an encrypted copy of itself, which is decoded by a decryption module. This article explains all the steps needed to write a C++ program which dynamically generates encryption algorithms in x86 assembly code. There is a wide variety of encryption algorithms available. A Polymorphic Virus is a type of ‘shape-shifting’ virus, producing malicious code that is able to replicate itself with new signatures but identical payloads over and over again. A Polymorphic Virus is a type of ‘shape-shifting’ virus, producing malicious code that is able to replicate itself with new signatures but identical payloads over and over again. Soon, virus creators developed decryption algorithms whose code was uniquely generated every time, which allowed viruses to be created which could not be detected using static signatures. The advantage of these algorithms is that they are heavily studied and their strengths and weaknesses are known. Our decryption function will use the standard 32-bit processor registers, and will obtain its one parameter from the stack using the stack frame pointer in the EBP register. Polymorphic viruses rely on mutation engines to alter their decryption routines every time they infect a machine. You may have heard of the term "polymorphic virus". They both are capable of changing themselves as they propagate. A virus replicates by itself and modifies the other programs by inserting its code. Due to the level of complexity of polymorphic engines, and the necessity of an in-depth understanding of assembly language for their creation, these days polymorphic engines are rarely used (one exception to this is Virut which, I'd like to point out, is strongly suspected of being Polish in origin!). This approach proved inherently impractical, time-consuming, and costly. The full decryptor is built only during the first initialization phase, which makes the virus a slow polymorphic. Listing 10.Setting up the return value of the decryption function (the size of the decrypted data) as well as any other final values we wish to place in registers. A similar technique is also used in debugger detection, where the fnstenv instruction will reveal that the most recently executed FPU instruction is not part of our program, but refers to some other FPU instruction, which is directly or indirectly executed by the debugger. Of course, the viruses needed to contain decryption routines, and these were quickly added to virus signature databases. Pseudoinstructions will be randomly generated for the encryption process, and they will later be used to generate the decryption code. Unknown 16 September 2018 at 06:46. Thanks to this, the library can be used to target code for 32- and 64-bit environments. Home Information technology Computer program Malware Computer virus Polymorphic code. I have included the class header below, followed by the implementation of the main function which generates the polymorphic code. In 2015, it took the combined efforts of the FBI and Europol to bring down a botnet running advanced polymorphic malware called Beebone. One virus author even created a tool kit called the “Dark Avenger’s Mutation Engine” (also known as MTE or DAME) for other virus writers to use. In computing, polymorphic code is code that uses a polymorphic engine to mutate while keeping the original algorithm intact. In software engineering, it depicts the idea that various kinds can be gotten through a similar interface. In addition, attackers use polymorphic code to continuously mutate malware and evade anti-virus detection. If you possess any shareware program which is protected by an exe-protector, there is a 99% chance that it uses a polymorphic encryption engine. Two other polymorphic viruses by the name of Tequila and Maltese Amoeba appeared in … Cybercriminals are constantly updating and morphing their virus code. Par conséquent, n’utilisez pas ce virus à des fins malveillantes. Sound simple? Once in a while I will send a free newsletter with: If you're interested in software protection technologies, cryptography & reverse engineering — give it a try! The initial exploit of a system often comes from human error, performing an action like downloading and running an infected email attachment, or visiting a website that has been compromised. Education. Polymorphic Virus Definition. A polymorphic virus uses a variable encryption key to change each copy of the virus. For example, 1+3 and 6-2 both achieve the same result while using different values and operations. signature-based identification programs. Our algorithm will use a randomly generated encryption key, but to prevent the key appearing directly in the code, we will encrypt it with a second, random key. Our decryption function will return a value of type DWORD (a 32-bit value corresponding to unsigned int), which indicates the size of the decrypted data. The first type are block cipher algorithms (data is encrypted in blocks of fixed size), including: There are also stream cipher algorithms (which encrypt data one byte at a time), such as the popular RC4 algorithm. Here are the steps any company should take to avoid falling victim to Polymorphic Viruses. This value will be returned in the EAX register. Each time a file infected with polymorphic virus is executed; it not just replicates itself, but changes the codes. Because one polymorphic virus could have hundreds or thousands of variants it makes it more difficult to detect every variant of the virus. in the Metasploit framework. Unlike symmetric encryption algorithms, where a leaked key means anyone can read the message, asymmetric encryption algorithms ensure that only the holder of the private key can decrypt the message. However, there are a number of asymmetric encryption functions, based on public key infrastructure. Windows' DEP (Data Execution Prevention) feature will throw an exception if you attempt to call the function. This allows someone who has a normal … Now that you have seen the successive elements of the operation of our polymorphic engine, it's time to bring it all together. In this article, we will cover all the steps necessary to create a simple polymorphic engine, which will serve to encrypt any supplied data, and generate a unique decryption procedure, with the encrypted data embedded within it. Another reason for the attraction is that polymorphic code is harder for researchers to pick apart and track down its shifting series of operations. Listing 2.Random selection of registers for the decryption function. When all your preparations and protections fail you, having cybersecurity insurance to help you recover quickly and effectively can mean the difference between a complete failure of your company and just a bad year. (You can also recognize an infected file by the string "-----this is silly python virus-----" which is printed whenever the infected program is executed.) This technique is sometimes used by computer viruses, shellcodes and computer worms to hide their presence. We take advantage of the fact that this instruction stores a return address on the stack before jumping to a chosen memory address. Written Information Security Policy (WISP). Developers that design the detection programs have to write extra lines of code to make the programs better at detecting the virus infections. Alignment between functions is normally achieved with the 1-byte instruction nop (no-operation) or int3 (an interrupt for the purpose of trapping into a debugger). This factoring process currently takes an enormous time. Listing 19.Decryption function in another variant. A polymorphic virus is a complex computer virus that can adapt to the various defenses you impose. That is, the code changes itself each time it runs, but the function of the code will not change at all. If memory addresses are correctly aligned, the data can be stored in the fast memory attached to the processor known as L1 cache. malware malware-research information-security malware-samples malware-development linux-malware malware-sample parasite shellcode-injection elf-virus code-injector infector elf-infector infect-binaries segment-padding … Note: Les dommages causés par ces virus sont irréversibles # 1 Désactiver Internet de manière permanente. Make sure you install all system and software updates to everything. In the case of RSA, cracking the public key involves splitting it into its two prime factors (RSA public keys are the product of two very large prime numbers). The first recorded polymorphic engines date back to the year 1990. Before the loop we will initialize the register we have called regSize with the number of blocks which need to be decrypted. • The idea is to encrypt the code with a random key and decrypt it at runtime. It has the potential to contaminate your data by writing certain malicious codes. Gifts, freebies, discount codes & exclusive promotions, Anti-cracking software protection tips & tricks, Software protection programming implementation ideas, Polymorphic Encryption Algorithms — Generating Code Dynamically, https://en.wikipedia.org/wiki/Block_cipher, https://en.wikipedia.org/wiki/Stream_cipher, https://en.wikipedia.org/wiki/Pretty_Good_Privacy, https://en.wikipedia.org/wiki/RSA_(algorithm), https://en.wikipedia.org/wiki/RSA_Factoring_Challenge, https://en.wikipedia.org/wiki/ElGamal_encryption, https://en.wikipedia.org/wiki/Elliptic_curve_cryptography, http://www.woodmann.com/collaborative/tools/index.php/RSA-Tool_2, http://www.woodmann.com/collaborative/tools/index.php/ECCTool, https://en.wikipedia.org/wiki/Polymorphic_code, http://krebsonsecurity.com/2013/01/polish-takedown-targets-virut-botnet/, https://en.wikipedia.org/wiki/Data_Execution_Prevention, software protection systems against cracking, RSATool, a tool for factoring public keys, Data Execution Prevention (DEP) mechanism, generating spurious instructions, known as, generating white noise – that is, instructions which don't affect the operation of the function (e.g. This group of algorithms includes: The encryption component of these algorithms uses a public key, while the decryption component requires a private key. Protect yourself no differently than with Fire, Flood, Errors & Omissions, or car insurance with Cybersecurity Insurance. This approach to the delta offset calculation is sometimes used in exploits, e.g. Add your article. Imagine a threat that can adapt to every form of defense you throw at it, a threat that constantly changes to avoid detection, a threat that is relentless. These viruses repeatedly change their overt characteristics in an attempt to evade and outwit your computer’s defenses and sabotage your system. Listing 12.Aligning the size of the decryption function to the specified granularity. This threat continues to grow. Some well-known algorithms included: In most cases, this type of encryption was used in executable file infectors. In our case, we work out the location of our "encrypted" data by adding the number of bytes between the delta_offset: label and the end of the function. adding a value to a random register and then taking it away again), generating equivalent instructions (code mutations) in various forms, joined by random comparisons and jumps, generating additional helper functions, e.g. Music video code . This random choice of registers will contribute to the generated code being different each time. Heuristic based solutions examine the actions and activities taken by code running on your system and prevent certain things from happening: for example, encrypting files should never happen and many heuristic programs prevent that helping you avoid a ransomware attack. We could add additional features, such as: This can all be taken quite a long way, especially making use of a library like AsmJit, which greatly simplifies the dynamic generation of assembly code, including the use of all current extensions of x86 and x64 processors. Instructions which access memory are faster if the data they read or write is aligned, i.e. For instance, our encrypted data is accessed in 32-bit blocks (since we are using 32-bit registers), which means memory addresses should be divisible by 4. Now that the entire code of the function has been generated, we can write out the encrypted data block, so it will follow the code of the function. The code of the polymorphic engine takes about half of the actual virus code, and there are random byte-based blocks inserted between the generated code chains of the decryptor. Polymorphic malware also makes changes to code to avoid detection. fugenit.co.za. Sign up with CyberHoot today and sleep better knowing your. Non-aligned addresses will be read from the slower L2 cache or directly from the computer's RAM. For small blocks of data, this does not create a noticeable difference, but for large buffers the performance reduction can be significant and should be taken into account. An interesting alternative for calculating a delta offset address involves the use of the FPU instruction fnstenv, which stores the environment state of the FPU. Listing 14.Place the encrypted data block after the end of the decryption function. This means that antivirus vendors cannot test their scanner's detection rate efficiently because the infected PC must be … Already in the days of MS-DOS, some computer viruses were encrypted by their creators in order to evade detection by antivirus software. fugenit.co.za. Polymorphism in V2PX/1260. The virus rebuilds itself on the stack with push instructions. Antivirus researchers in 2020 determined that 97 percent of newly identified viruses had polymorphic properties. 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