AUSCERT External Security Bulletin Redistribution
              ESB-2000.316 -- NetBSD Security Advisory 2000-015
                    format-string bugs in passwd/libutil
                               27 October 2000


	AusCERT Security Bulletin Summary

Product:                passwd/libutil
Vendor:                 NetBSD
Operating System:       NetBSD
Impact:                 Root Compromise
Access Required:        Local

- --------------------------BEGIN INCLUDED TEXT--------------------


                 NetBSD Security Advisory 2000-015

Topic:		format-string bugs in passwd/libutil
Version:	all releases up to and including 1.4.2
Severity:	local root compromise possible
Fixed:		2000/10/03 in -current and netbsd-1-5 branches
		2000/10/04 in netbsd-1-4 branch.
		fix will be in the 1.4.3 and 1.5 releases


The pw_error() function of the system libutil library, used by several
programs including the setuid passwd program, was vulnerable to a
format string attack.

Technical Details

pw_error passed its first argument to the warn(3) function, which
interprets its first argument as a format string.  in certain
circumstances, passwd(1) passes a value derived from untrusted user
input to pw_error().

Solutions and Workarounds

The problem was fixed in NetBSD-current on 2000/10/03; systems running
NetBSD-current dated from before that date should be upgraded to
NetBSD-current dated 2000/10/04 or later.  The two active release
branches were both fixed by 2000/10/05.

Systems running releases older than NetBSD 1.4 should be upgraded to
NetBSD 1.4.2 before applying the fixes described here.

Systems running 1.4.2 should apply the following patch to
lib/libutil/passwd.c usign the patch(1), and rebuild and reinstall the
"libutil" library.  On systems which do not support shared libraries,
you should then rebuild and reinstall the "passwd" command.

- - --- lib/libutil/passwd.c    1999/12/04 20:00:55
+++ lib/libutil/passwd.c    2000/10/04 14:11:02
@@ -319,7 +319,7 @@
        int err, eval;
        if (err)
- - -               warn(name);
+               warn("%s", name);
        warnx("%s: unchanged", _PATH_MASTERPASSWD);

Revision History

	20001024	Initial draft of advisory.

More Information

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.ORG/ and http://www.NetBSD.ORG/Security/.

Copyright 2000, The NetBSD Foundation, Inc.  All Rights Reserved.

$NetBSD: NetBSD-SA2000-015.txt,v 1.3 2000/10/26 15:22:01 sommerfeld Exp $

Version: 2.6.3ia
Charset: noconv


- --------------------------END INCLUDED TEXT--------------------

This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content.  The decision to use any or all of this information is
the responsibility of each user or organisation, and should be done so in
accordance with site policies and procedures.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the original authors to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:


If you believe that your system has been compromised, contact AusCERT or
your representative in FIRST (Forum of Incident Response and Security

Internet Email: auscert@auscert.org.au
Facsimile:	(07) 3365 7031
Telephone:	(07) 3365 4417 (International: +61 7 3365 4417)
		AusCERT personnel answer during Queensland business hours
		which are GMT+10:00 (AEST).
		On call after hours for emergencies.

Version: 2.6.3i
Charset: noconv
Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key