![]() ![]() Wikipedia supplied a really nice graph describing encryption using the CBC mode: Although the authenticated GCM mode is stronger than the CBC mode (which has known weaknesses), it does not add any additional security here. ![]() I’m not going to dig into how that cipher is working internally as it is highly mathematical and reserved for universities □įor this assignment, I’ve chosen to use the CBC mode and the 256 bit-key variant, which means that the encryption key is 32 bytes strong. It supports modes, such as Cipher Block Chaining (CBC) and authenticated encryption using Galois Counter Mode (GCM). It has a block size of 128 bits and key sizes of either 128, 192 or 256 bits. Although it is not widely used but part of the offered TLS ciphers-suites, it is has the security levels comparable to AES. Use the Crypto++ library to keep the wheel inventedĬamellia was developed by Misubishi Electric and NTT Japan and is a symmetric key block cipher such as AES.Use Camellia as an encryption algorithm.After having a quick look at blog posts of some other student’s about this assignment, I decided to go the following way: Choosing an encryption cipher and programming languageĪs a personal goal, I wanted to do something different than all other SLAE students have done so far. A list of crypter techniques can be found on. Therefore to bypass these signature-based AVs and make the crypter “FUD” (fully undetectable), crypters are a widely used approach. This principle is extended by some heuristic techniques aimed to detect new viruses as well as variants of existing ones by simulating what happen upon execution of a malicious file. If such a pattern is detected by an AV, the file is marked as a virus. This means all AV vendors maintain a database of virus signatures, which is built from detected viruses and specific patterns found in them. Basically, this principle also applies to a crypter – its main purpose is to conceal the real identity and functionality of a payload from antivirus software (henceforth referred to as “AV”).ĪV software (just like provided by Avira, Kasperky or Bitdefender) uses mostly a signature-based approach. So why do you encrypt things? Because you don’t want them to be read, which means you want to primarily secure its confidentiality (with some encryption algorithms like AES-GCM you secure the integrity as well). What is a crypter?īasically the term “crypter” is derived from “encryption”, which means its purpose is to encrypt and decrypt a specific payload using a cryptographic encryption algorithm like 3DES, AES, CAMELLIA or even RSA. Use any existing encryption schema (including own)īut before digging into the technical details of my crypter, let’s first discuss the basics.This blog post gives you some insights about crypters and finalizes my SecurityTube Linux Assembly Expert (SLAE) certification. You will also find this tool in the arsenal of every advanced penetration tester and it is the obvious standard for an advanced persistent threat (APT). Do you want to fool antivirus software? When you look through hacking forums for a solution to this, you will likely encounter the term “crypter”. ![]()
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