Sun RCP vulnerability

Original issue date: October 26, 1989
Last revised: September 17, 1997
Attached copyright statement

A complete revision history is at the end of this file.

A problem has been discovered in the SunOS 4.0.x rcp.  If exploited, this problem can allow users of other trusted machines to execute root-privilege commands on a Sun via rcp.

This affects only SunOS 4.0.x systems; 3.5 systems are not affected.

A Sun running 4.0.x rcp can be exploited by any other trusted host listed in /etc/hosts.equiv or /.rhosts.  Note that the other machine exploiting this hole does not have to be running Unix; this
vulnerability can be exploited by a PC running PC/NFS, for example.

This bug will be fixed by Sun in version 4.1 (Sun Bug number 1017314), but for now the following workaround is suggested by Sun:

Change the 'nobody' /etc/passwd file entry from

nobody:*:32767:32767:Mismatched NFS ID's:/nonexistant:/nosuchshell
If you need further information about this problem, please contact CERT/CC by electronic mail or phone.
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CERT/CC Contact Information

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Pittsburgh PA 15213-3890

CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends.

Using encryption

We strongly urge you to encrypt sensitive information sent by email.  Our public PGP key is available from

If you prefer to use DES, please call the CERT hotline for more information.

Getting security information

CERT publications and other security information are available from our web site

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Copyright 1989 Carnegie Mellon University.

Revision History
September 17,1997  Attached Copyright Statement