DTPacker Packers

DTPacker is a .NET packer or downloader which although seeing considerable variety in the first stage, uses a second stage with a fixed password as part of the decoding.

The main difference between a packer and a downloader is the location of the payload data which is embedded in the former and downloaded in the latter. DTPacker uses both …

Deobfuscate/Decode Files or Information Defense Evasion [Mitre]

Adversaries may use Obfuscated Files or Information to hide artifacts of an intrusion from analysis. They may require separate mechanisms to decode or deobfuscate that information depending on how they intend to use it. Methods for doing that include built-in functionality of malware or by using utilities present on the system.

One such example is use of certutil to …

C2 via FTP(S) Network Evasion

C2 via FTP is a technique that utilizes the File Transfer Protocol (FTP) to establish command and control communication between an attacker and victim systems. It involves sending commands and receiving responses within FTP sessions, effectively using FTP as a conduit for covert communication.

To implement C2 via FTP, an attacker needs control over an FTP server, and must …

LimeCrypter Packers

Limecrypter is a sophisticated obfuscation tool designed for both native and .NET files. It employs a unique approach to secure payloads by encrypting them within a .NET-based stub. This stub acts as a container for the encrypted payload, ensuring its contents remain concealed until execution.

Cronos-Crypter Packers

Cronos-Crypter is an open-source crypter publicly available on GitHub. The crypter applies AES encryption or XOR obfuscation to a selected payload before storing it as a .NET resource of a final generated .NET executable payload. Cronos-Crypter contains multiple capabilties for persistence and defense evasion. An operator may select persistence via a Windows Registry autorun key or a Scheduled Task. An …

VBA Purging Antivirus/EDR Evasion

VBA Purging is an obfuscation technique designed to evade detection mechanisms used in malware analysis. When a VBA macro is added to a Microsoft Office document, it is stored in two sections: the PerformanceCache (compiled VBA code) and the CompressedSourceCode (compressed VBA source code). In VBA Purging, the PerformanceCache (compiled code) is completely removed from the module stream, along with …

Base64 Data Obfuscation

Base64 is a simple encoding scheme that is often used by malware to represent binary data in an ASCII string. This allows the malware to encode and transmit binary data, such as a payload or network traffic, in a way that is more compact and easier to transmit over text-based communication channels.

Base64 uses a 64-character alphabet to encode …

Caesar Cipher Data Obfuscation

The Caesar Cipher is a simple encoding algorithm that was used during the Roman Empire to hide secret messages. In this algorithm, each letter of the plaintext is replaced with a letter that is a fixed number of positions down the alphabet. For example, if the shift value is 3, then the letter "A" would be replaced with "D", "B" …

ROL Data Obfuscation

ROL, or Rotate Left, is a simple encoding algorithm similar to the Caesar Cipher. In the ROL algorithm, each letter of the plaintext is replaced with a letter that is a fixed number of positions down the alphabet. For example, if the rotation value is 3, then the letter "A" would be replaced with "D", "B" would be replaced with …

Custom Encoding Data Obfuscation

Malware often uses custom encoding schemes to conceal their payloads and avoid detection. These custom schemes can be full custom layers, or they can be variations of known algorithms such as XOR or Base64. Using custom encoding schemes allows malware to encode their payloads in a unique way that can be difficult for security tools and forensic investigators to detect.

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