Pawel,
I found exactly what you say in my VISTA workstation in this folder:
C:\Users\All Users\Symantec\SyKnAppS
The two dll files are dated 11/07/2010 (earlier than my latest update push).
In addition, a search on my VISTA Professional work station finds SyKnAppS.dll and Patch25.dll in these folders:
C:\SWTOOLS\Apps\NORTONIS\US\NCO\NCO
C:\SWTOOLS\Apps\NORTONIS\US\NAV\External
Both files show Modified 10/11/2006 and Created 10/22/2007
I also found Patch25d.dll in
C:\Program Files\Symantec\Symantec Endpoint Protection
Richard