Malware authors must constantly iterate on their techniques in order to stay relevant in today’s fast moving Information Security environment. The Upatre downloader has been around for nearly three years and has consistently evolved its anti-analysis capabilities to better ensure payload delivery. Using Palo Alto Networks AutoFocus, we identified several thousand functionally identical Upatre binaries with unique hashes that exhibited unusual anti-analysis behaviors. We dove into the most recent phishing campaign to identify the new anti-analysis routines designed to maneuver around behavioral analysis systems.
Diving In
Upatre’s new technique takes advantage of undocumented NtQuerySystemInformation structures. It attempts to call the ZwQuerySystemInformation API a few times to determine the idle time of the system. The ZwQuerySystemInformation API takes a SYSTEM_INFORMATION_CLASS as an argument for what to query. There are several options to query for, all with respective structures. Continue reading "Upatre: Old Dog, New [Anti-Analysis] Tricks"

