Virus:Win32/Nuwar.A is a file modifying virus. This virus modifies device drivers on an infected system, specifically files named kbdclass.sys and tcpip.sys. The modified drivers load Nuwar into memory on system startup, and in some cases, the virus may block system file checker from displaying notifications of these system file modifications.
Nuwar uses advanced stealth techniques in order to hide its files and associated registry modifications. Hence, it is unlikely that users could easily ascertain the presence of the Trojan on the infected computer.