Sun Microsystems Sun Workstation 100U System Manager's Manual page 234

REXECD(8C)
MAINTENANCE COMMANDS
REXECD(8C)
"/bln/_ha .....
The user's login shell could not be started.
BUGS
Indicating "Login incorrect" as opposed to "Password incorrect" is a security breach which allows
people to probe a system for users with null passwords.
A facility to allow all data exchanges to be encrypted should be present.
SEE ALSO
inetd(8C)
Sun Release 1.1 Last change: 28 October 1983 79