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npd(8)
Systems Affected:NeXT Release 1.0 and 1.0a
Problem: On NeXT computers running Release 1.0 or 1.0a that also have publicly accessible printers, users can gain extra permissions via a combination of bugs.

Computer intruders are able to exploit this security problem to gain access to the system. Intruders, local users and remote users are able to gain root access.

Solution: NeXT computer owners running Release 1.0 or 1.0a should do two things to fix a potential security problem. First, the binary /usr/lib/NextPrinter/npd must be replaced with a more secure version. This more secure version of npd is available through your NeXT support center. Upon receiving a copy of the more secure npd, you must become root and install it in place of the old one in /usr/lib/NextPrinter/npd. The new npd binary needs to be installed with the same permission bits (6755) and owner (root) as the old npd binary. The commands to install the new npd binary are the following: 
  # /bin/mv /usr/lib/NextPrinter/npd /usr/lib/NextPrinter/npd.old
  # /bin/mv newnpd /usr/lib/NextPrinter/npd
          (In the above command, "newnpd" is the npd binary
          that you obtained from your NeXT support center.)
  # /etc/chown root /usr/lib/NextPrinter/npd
  # /etc/chmod 6755 /usr/lib/NextPrinter/npd
  # /etc/chmod 440 /usr/lib/NextPrinter/npd.old
The second half of the fix to this potential problem is to change the permissions of directories on the system that are currently owned and able to be written by group "wheel". The command that will remove write permission for directories owned and writable by group "wheel" is below. This command is all one line, and should be run as root. 
  # find / -group wheel ! -type l -perm -20 ! -perm -2 -ls -exec chmod
  g-w {} \; -o -fstype nfs -prune

Aleph One / aleph1@underground.org
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