Main function of Virus.Win32.Xpaj is a botnet client which is used by the virus to transmit data from an infected PC. Here you can read more about botnets and their usage.
To disinfect a system infected with malware Virus.Win32.Xpaj.a,b,c,gen use the tool XpajKiller.exe.
Disinfection of an infected system:
WarningThe System restore function should be disabled before attempting to disinfect a system.
Download the archive XpajKiller.zip and extract it into a folder on the infected (or potentially infected) PC using an archiver program (for example, WinZip).
Run the file XpajKiller.exe.
Wait for the scan and disinfection to finish. A reboot might require after disinfection.
If started without switches, the tool will:
Scan and disinfection of files on all hard disk drives.
While scanning hard disk drives, the tool will also perform a check of executable files of all running processes every 10 seconds.
Terminate detected infected processes and disinfect infected files.
Optional switches to run the tool from command prompt:
-l - write log to the file.
-v - detailed logging (must be used in combination with the parameter -l).
-s ;- scan in “silent” mode (without opening console box).
-y - when the utility finishes, its window will be closed.
-p – scan a specific folder.
-r - scan removable drives (flash), external USB and FireWire hard disks.
-n - scan network drives.

http://support.kaspersky.com/faq/?qid=208285208

Portable
http://support.kaspersky.com/downloads/utils/xpajkiller.exe
http://support.kaspersky.com/downloads/utils/xpajkiller.zip

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