rdriv.sys is part an SDBot/Esbot infection. Some of the commonly seen associated entries in a HJT log are below.
O23 - Service: iTunes Music Service (iTunesMusic) - Apple - C:\WINDOWS\iTunesMusic.exe
O23 - Service: Windows lsass Service (lsass) - Unknown owner - C:\WINDOWS\lsass.exe
O23 - Service: Workstation Service Library (Microsoft Locator Service) - Unknown owner - C:\WINDOWS\wkssvc.exe
O23 - Service: Windows Management Construct (winmgmc) - Unknown owner - C:\WINDOWS\winmgc.exe
O23 - Service: Windows Update Service - Unknown owner - C:\WINDOWS\pwnsvc.exe
O23 - Service: AOL Instant Messanger (AIM) - Unknown owner - C:\WINDOWS\aim.exe
O23 - Service: AOL Instant Messenger - Unknown owner - C:\WINDOWS\aims.exe
O23 - Service: sdktemp - Unknown owner - C:\WINDOWS\sdktemp.exe
However, you might not see any indications at all. Only the AV detection of the file. You will also see this file in a HJT full startup report.
rdrivrem will remove all of the known registry entries and files to date. rdriv.sys is indeed a rootkit, and it's recommended by many to do a complete format and re-install once a system has been compromised by a rootkit. However, I'm not completely convinced that it's necessary. Once the files/regs are removed, it's impossible for it to continue to work, except that it may have allowed other malware to be installed. Making sure a system is free of any other malware should remove any risk the rootkit may have introduced.
www.atribune.org is a site run by fellow malware fighter Atribune, and yes, it's a very useful site.
