The C# obfuscator replaces symbol names with barely distinguishable Unicode characters. Strings are not stored in the data section, but instead constructed on the stack using mov-opcodes.
#Online free crypter code
Hence, AV detection is limited to the stub itself.Īssembly code is obfuscated by nop-like instructions intermingled with the actual code, such as an increment followed by a decrement. Because the resulting data has no repeating patterns, it is impossible to identify this particular encoding and infer YARA rules from it. To decrease entropy, the encrypted shellcode is intermingled with null-bytes at randomized offsets. The shellcode is encrypted using a proprietary 4-byte XOR stream cipher. Stage 2 contains all the “suspicious” code that is not readable at scantime and not decrypted, if an emulator is detected. To mitigate AV detections, only the stub requires adjustments. The second stage is position independent shellcode that retrieves function pointers from the PEB and handles the payload. The fundamental concept is that the stub only contains code to detect emulators and to decrypt and pass execution to the next layer. This graph illustrates the execution flow of the native stub decrypting and executing a PE file. The exact implementation is fine tuned to decrease detection and is subject to change in future releases.
Obfuscation and evasive features are fundamental to the design of PEunion and do not need further configuration.
Legitimate files with no known signatures can be written to the disk. If the executable is a native PE file, RunPE (process hollowing) is used. Typically, an executable is decrypted and executed in-memory by the stub. A file can either be embedded within the compiled executable, or the stub downloads the file at runtime. Multiple files can be compiled into the stub. Specify icon, version information & manifest Two stubs are available to choose from, both of which work in a similar way.Native: Written in assembly (FASM)
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