APIs

Component Object Model (COM) is a technology in Windows that enables object activation, inter-process communication, and automation across different programming languages. Malware exploits COM interfaces for activities such as lateral movement, execution, downloading, exfiltration, persistence, evasion, system discovery, and automation of Windows and Office functionalities. Reverse engineering COM-heavy binaries involves navigating GUIDs and indirect vtable calls to understand malware mechanics. Research at the AVAR 2025 conference and CARO 2026 workshop discusses methodologies for analyzing COM binaries and case studies of malware families that utilize COM. COM is an application binary interface (ABI) model that allows software components to be reused and enables interaction between different programming languages through interfaces defined at the binary level. Distributed COM (DCOM) allows clients to activate COM objects on remote systems. COM classes are identified by unique class identifiers (CLSIDs), and interfaces by interface identifiers (IIDs). The Windows registry stores COM registration data, with classes and interfaces located under specific keys. Malware often acts as a COM client, utilizing the COM runtime to instantiate classes and request interfaces. ProgIDs provide human-readable registry entries for COM classes. The CoCreateInstance function helps create class objects by resolving CLSID registrations. All COM interfaces derive from IUnknown, which manages object lifetimes and interface querying. COM has its own security model, and identifying classes and interfaces used by malware is crucial for threat researchers. Tools like ComView and OleView.NET assist in inspecting COM registrations. The analysis workflow includes identifying activation API calls, extracting CLSID and IID values, consulting registry definitions, and mapping vtable calls. Qakbot, a banking trojan, exemplifies the use of COM in malware, with its architecture enabling malicious activities like credential theft. Dynamic analysis tools can log COM-related calls in real-time to trace execution flow. Notable malware families that utilize COM include Gh0stRAT, which uses Task Scheduler COM interfaces, and the Attor platform, which employs BITS for file transfers. WarmCookie demonstrates the use of COM for persistence through Task Scheduler. Understanding COM's role in malware is essential for cybersecurity professionals.