NixImports

Created the Sunday 14 January 2024. Updated 1 month, 2 weeks ago.

A .NET malware loader employs API-Hashing and dynamic invocation to circumvent static analysis. NixImports utilizes managed API-Hashing to dynamically determine most of its required functions during runtime. For function resolution, HInvoke needs two specific hashes: typeHash and methodHash, representing the type name and the method's full name, respectively. At runtime, HInvoke scans the entire mscorlib to locate the corresponding type and method. Consequently, HInvoke doesn't generate any import references for the methods accessed through it.

Additionally, NixImports is designed to minimize the use of well-known methods. Wherever possible, it opts for internal methods over their standard wrappers. This strategy helps in evading the basic hooks and monitoring systems used by certain security tools.


Technique Identifier

U1434

Technique Tags

NixImports packer .net


Detection Rules

Contributors

Additional Resources

External Links

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