Dipartimento di Ingegneria informatica, automatica e gestionale

Distributed execution designs challenge behavioral analyses of anti-malware solutions by spreading seemingly benign chunks of a malicious payload to multiple processes. Researchers have explored methods to chop payloads, spread chunks to victim applications through process injection techniques, and orchestrate the execution. However, these methods can hardly be practical as they exhibit conspicuous features and make use of primitives that anti-malware solutions and operating system mitigations readily detect. In this paper we reason on fundamental requirements and properties for a stealth implementation of distributed malware. We propose a new covert design, Rope, that minimizes its footprint by making use of commodity techniques like transacted files and return-oriented programming for covert communication and payload distribution. We report on how synthetic Rope samples eluded a number of state-of-the-art anti-virus and endpoint security solutions, and bypassed the opt-in mitigations of Windows 10 for hardening applications. We then discuss directions and practical remediations to mitigate such threats.