Cuckoo is an isolated virtual machine that assists and partially automates the analysis and reverse engineering of malware. It can be used to analyze malware and its components for Windows, suspicious document files, and obfuscated or otherwise dodgy scripts. It can be used to trace API calls and capture network taffic for analysis. It is also designed for extensibility, so you can implement your own analysis and reverse engineering processes to add to the virtual machine. Has a Github repository.

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Cuckoo is a system emulator written in Python for analyzing malware. It automates much of the process of reverse engineering malware samples, such as tracing execution, snapshotting memorry, tracing API and function calls, and dumping network traffic. Generates reports at the end of execution. Modular design, so it's easily customizable.