/System/Library/PrivateFrameworks/Heimdal.framework/Helpers/kcm kcm is a process based credential cache. The kcm daemon can hold the credentials for all users in the system. Access control is done with Unix-like permissions. The daemon checks the access on all operations based on the UID of the user. The tickets are renewed as long as is permitted by the KDC's policy. The kcm daemon can also keep a SYSTEM credential that server processes can use to access services.
The binary is a part of Heimdal private framework.