Windows Exploitation Technique Bypasses Registry Security Using `ntuser.man` for Malware Persistence

The ntuser.dat file in Windows stores user-specific settings and configurations in the registry (HKCU). A little-known technique allows bypassing this by using an ntuser.man file, which, if placed in the user profile directory, completely replaces ntuser.dat upon the next login without triggering alerts via registry callbacks or Windows APIs. This method, documented in a 2023 article by Rad Kawir from Deceptive Bytes, exploits mandatory profiles, originally designed for kiosks and shared workstations. The demonstration shows that an attacker with standard user access can export the HKCU registry in .reg format, add a persistence key (e.g., HKCU\Software\Microsoft\Windows\CurrentVersion\Run), then convert the file back to binary using the HiveSwarming tool to generate ntuser.man. Once placed in the profile, this file overwrites ntuser.dat upon reboot, enabling the execution of malicious code (e.g., calc.exe or a C2 implant like Sliver). The technique operates at medium integrity and does not require administrative privileges. It was first mentioned in 2010 on forums and later shared on cybercriminal platforms like RAMP in 2023. Countermeasures include detecting the presence of ntuser.man or analyzing profile path modifications in Active Directory.