Information
The file /etc/passwd must not contain the entry +::0:0::: since otherwise access with the name '+' without a password is possible. Should the entry be necessary, the password must be replaced by '*' (you must check whether access has actually been blocked!). Nevertheless, there still will be the risk that, in case of inadvertent deletion of the first column (i.e. '+'), privileged access will be possible without a password and without a user name.
The situation is similar as regards the group file /etc/group and all other security-relevant files which are to be made accessible network-wide through the NIS, e.g. /etc/passwd, etc/group, or etc/bootparams.
Safeguard Catalogues: S 5: Communications
S 5.18: Use of the NIS security mechanisms