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Reversing TDSS: The x64 Dollar Question

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In the two years since the Win32/Olmarik family of malware programs (also known as TDSS, TDL and Alureon) started to evolve, its authors have implemented a notably sophisticated mechanism for bypassing various protective measures and security mechanisms embedded into the operating system. Read more here Reverse Engineering Malware

The fourth version of the TDL rootkit family (TDL4) is the first reliable and widely spread bootkit to target x64 operating systems (Windows Vista and Windows 7). Since TDL4 started to spread actively in August 2010, several versions of the malware have been released. By comparison with its predecessors, TDL4 is not just characterized by modification of existing code, but to all intents and purposes can be regarded as new malware. Among the many changes that have been applied as it developed, the most radical were those made to its mechanisms for self-embedding into the system and surviving reboot. One of the most striking features of TDL4 is its ability to load its kernel-mode driver on systems with an enforced kernel-mode code signing policy (64-bit versions of Microsoft Windows Vista and Windows 7) and perform kernel-mode hooks with kernel-mode patch protection policy enabled. This makes TDL4 a powerful weapon in the hands of cybercriminals. In this article, we consider the PPI (Pay Per Install) distribution model used by both TDL3 and TDL4, and the initial installation.