FLOWMINER: Automatic Summarization of Library Data-Flow for Malware Analysis

Malware often conceal their malicious behavior by making unscrupulous use of library APIs. Hence any accurate malware analysis must track data-flows not only through the application but also through the library. Libraries like Android (2 mLOC) are too large to be analyzed repeatedly with each application, hence we need to compute data-flow summaries of libraries that are expressive enough to reveal possible malicious flows, and compact to be included in malware analysis along with each application. We present FLOWMINER, a novel approach to automatically extract the data-flow summary of a Java library, given its source or bytecode. FLOWMINER's summaries are fine-grained, i.e., preserve key artifacts from the original library to enable accurate context, object, field, flow and type-sensitive malware analysis of applications in conjunction with the library. Unlike prior summarization techniques, FLOWMINER resolves method calls to anonymous classes to a single target, making it more precise. FLOWMINER's summaries are compact, e.g., contain only about a third (fourth) of the nodes (edges, resp.) in the data-flow semantics of recent versions of Android. FLOWMINER's summaries are stored in XML, allowing any analysis tool to use them for analysis.