RegSetInfoKey as an "operation" on the registry. Process Monitor operations do not necessarily map directly to Native symbols, however, it seems that this operation uses NtSetInformationKey. When we examine that function though, we see that it has a parameter:
IN KEY_SET_INFORMATION_CLASS InformationClass. Finally, undocumented.ntinternals.net states:
Currently only KEY_WRITE_TIME_INFORMATION is supported.
When we look up KEY_WRITE_TIME_INFORMATION, the definition is just a simple data structure which stores the last write time to the registry key. So the question then becomes, when ProcMon displays a last write time, but no RegSetKey or other write occurs, what is the purpose for setting this value and is a simple write to this member what is actually occurring?