ORA-01031: insufficient privileges

cause for this particular case was
Somebody modified the sqlnet.ora file by putting an entry SQLNET.AUTHENTICATION_SERVICES = (NONE)

This entry is meant to enable one or more authentication services. If authentication has been installed,
then it is recommended that this parameter be set to either none or to one of the authentication methods.
none - for no authentication methods, including Microsoft Windows native operating system authentication. When SQLNET.AUTHENTICATION_SERVICES is set to none,a valid user name and password can be used to access the database.
all  - for all authentication methods.
nts  - for Microsoft Windows native operating system authentication.
Authentication Methods Available with Oracle Advanced Security:
kerberos5  - for Kerberos authentication.
radius - for RADIUS authentication.
tcps  - for SSL authentication.

After making the change  "SLAVE COMMUNICATION ERROR WITH ASM ; TERMINATING PROCESS " observed in the alert log and the database instances went down.,ASM status was intermediate.
Restarting the cluster brought everything up except the ASM instance which complained "Insufficient Privilege to start"
While trying to start the ASM manually "ORA-01031: insufficient privileges message" was thrown.

Finally removing "SQLNET.AUTHENTICATION_SERVICES=(NONE)" entry from the sqlnet.ora file saved the day!