In-memory injection attacks are extremely challenging to reverse engineer because they operate stealthily without leaving artifacts in the system or in any easily observable events from outside of a virtual machine. Because these attacks perform their actions in memory only, current malware analysis solutions cannot expose their behavior. This paper introduces FAROS1 a reverse engineering tool for Windows malware analysis based on dynamic information flow tracking (DIFT), which can flag stealthy in-memory-only malware injection attacks by leveraging the synergy of: (i) whole-system taint analysis; (ii) per security policy-based handling of the challenge of indirect flows via the application of tags of different types, and (iii) the use of tags with fine-grained provenance information. We evaluated FAROS with six advanced in-memory-injecting malware and it flagged the attacks for all samples. We also analyzed FAROS' false positive rate with 90 non-injecting malware samples and 14 benign software from various categories. FAROS presented a very low false positive rate of 2%, which shows its potential towards practical solutions against advanced in-memory-only anti-reverse-engineering attacks.