This is a Windows system installed file with Windows File Protection (WFP) enabled.
csrss.exe has 40 known versions, the most recent one is 6.2.9200.16384 (win8_rtm.120725-1247). csrss.exe is run as a standard windows process in the context of the SYSTEM account with extensive privileges. During installation the program adds a job to the Task Scheduler. The average file size is about 6.21 KB. During the process's lifecycle, the typical CPU resource utilization is about 0.0021% including both foreground and background operations, the average private memory consumption is about 4.37 MB with the maximum memory reaching around 18.03 MB. Addionally, typically read and write I/O disk operations is about 8.58 KB per minute for reads and 0 Bytes per minute for writes.
Client/Server Runtime Subsystem, or csrss.exe, is a component of the Microsoft Windows NT operating system that provides the user mode side of the Win32 subsystem and is included in Windows 2000, XP, 2003, Vista, Server 2008 and 7. Because most of the Win32 subsystem operations have been moved to kernel mode drivers, in Windows NT 4 and later CSRSS is mainly responsible for Win32 console handling and GUI shutdown.
(Note, the behaviors below are for all versions of csrss.exe, select a unique version for details.)
United States installs about 46.73% of Client Server Runtime Process.