Articles / Red Hat: Updated ypserv pac…

Red Hat: Updated ypserv packages fix a denial of service vulnerability

The ypserv package contains the Network Information Service (NIS) server. A vulnerability has been discovered in the ypserv NIS server prior to version 2.7. If a malicious client queries ypserv via TCP and subsequently ignores the server's response, ypserv will block attempting to send the reply. This results in ypserv failing to respond to other client requests. Versions 2.7 and above of ypserv have been altered to fork a child for each client request, thus preventing any one request from causing the server to block. Fixed packages are available from updates.redhat.com.
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                   Red Hat Security Advisory

Synopsis:          Updated ypserv packages fix a denial of service vulnerability
Advisory ID:       RHSA-2003:173-01
Issue date:        2003-06-25
Updated on:        2003-06-25
Product:           Red Hat Linux
Keywords:          NIS ypserver DOS
Cross references:  
Obsoletes:         
CVE Names:         CAN-2003-0251
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1. Topic:

Updated ypserv packages fixing a denial of service vulnerability are now
available.

2. Relevant releases/architectures:

Red Hat Linux 7.1 - i386
Red Hat Linux 7.2 - i386, ia64
Red Hat Linux 7.3 - i386
Red Hat Linux 8.0 - i386
Red Hat Linux 9 - i386

3. Problem description:

The ypserv package contains the Network Information Service (NIS) server.

A vulnerability has been discovered in the ypserv NIS server prior to
version 2.7.  If a malicious client queries ypserv via TCP and subsequently
ignores the server's response, ypserv will block attempting to send the
reply.  This results in ypserv failing to respond to other client requests.

Versions 2.7 and above of ypserv have been altered to fork a child for each
client request, thus preventing any one request from causing the server to
block.

Red Hat recommends that users of NIS upgrade to these packages, which
contain version 2.8.0 of ypserv and are therefore not vulnerable to this issue.

4. Solution:

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade.  Only those
RPMs which are currently installed will be updated.  Those RPMs which are
not installed but included in the list will not be updated.  Note that you
can also use wildcards (*.rpm) if your current directory *only* contains the
desired RPMs.

Please note that this update is also available via Red Hat Network.  Many
people find this an easier way to apply updates.  To use Red Hat Network,
launch the Red Hat Update Agent with the following command:

up2date

This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

5. RPMs required:

Red Hat Linux 7.1:

SRPMS:
ftp://updates.redhat.com/7.1/en/os/SRPMS/ypserv-2.8-0.72E.src.rpm

i386:
ftp://updates.redhat.com/7.1/en/os/i386/ypserv-2.8-0.72E.i386.rpm

Red Hat Linux 7.2:

SRPMS:
ftp://updates.redhat.com/7.2/en/os/SRPMS/ypserv-2.8-0.72E.src.rpm

i386:
ftp://updates.redhat.com/7.2/en/os/i386/ypserv-2.8-0.72E.i386.rpm

ia64:
ftp://updates.redhat.com/7.2/en/os/ia64/ypserv-2.8-0.72E.ia64.rpm

Red Hat Linux 7.3:

SRPMS:
ftp://updates.redhat.com/7.3/en/os/SRPMS/ypserv-2.8-0.73E.src.rpm

i386:
ftp://updates.redhat.com/7.3/en/os/i386/ypserv-2.8-0.73E.i386.rpm

Red Hat Linux 8.0:

SRPMS:
ftp://updates.redhat.com/8.0/en/os/SRPMS/ypserv-2.8-0.80E.src.rpm

i386:
ftp://updates.redhat.com/8.0/en/os/i386/ypserv-2.8-0.80E.i386.rpm

Red Hat Linux 9:

SRPMS:
ftp://updates.redhat.com/9/en/os/SRPMS/ypserv-2.8-0.9E.src.rpm

i386:
ftp://updates.redhat.com/9/en/os/i386/ypserv-2.8-0.9E.i386.rpm



6. Verification:

MD5 sum                          Package Name
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db17bee9fdb6d553dbb57850abff456a 7.1/en/os/SRPMS/ypserv-2.8-0.72E.src.rpm
a51f5a9adf6ff4f255678e7407982a7e 7.1/en/os/i386/ypserv-2.8-0.72E.i386.rpm
db17bee9fdb6d553dbb57850abff456a 7.2/en/os/SRPMS/ypserv-2.8-0.72E.src.rpm
a51f5a9adf6ff4f255678e7407982a7e 7.2/en/os/i386/ypserv-2.8-0.72E.i386.rpm
c300d319d7e883d5197b63f2e23fec88 7.2/en/os/ia64/ypserv-2.8-0.72E.ia64.rpm
c1977878cc0c0f90a9d55a4ae3b3bfe3 7.3/en/os/SRPMS/ypserv-2.8-0.73E.src.rpm
4af8d607cf8ba600288b5a5f164bf2f6 7.3/en/os/i386/ypserv-2.8-0.73E.i386.rpm
a606ee4aedc08cf7065e39d79b5e7474 8.0/en/os/SRPMS/ypserv-2.8-0.80E.src.rpm
9b72853f34de52966ff929218d1948bf 8.0/en/os/i386/ypserv-2.8-0.80E.i386.rpm
158b6b1ea17e996f2909ed98e444d683 9/en/os/SRPMS/ypserv-2.8-0.9E.src.rpm
86be6a349c1770893c6965611e29dc70 9/en/os/i386/ypserv-2.8-0.9E.i386.rpm


These packages are GPG signed by Red Hat for security.  Our key is
available from http://www.redhat.com/security/keys.html

You can verify each package with the following command:

    rpm --checksig -v 

If you only wish to verify that each package has not been corrupted or
tampered with, examine only the md5sum with the following command:

    md5sum 


7. References:

http://www.linux-nis.org/nis/ypserv/ChangeLog
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0251

8. Contact:

The Red Hat security contact is .  More contact
details at http://www.redhat.com/solutions/security/news/contact.html

Copyright 2003 Red Hat, Inc.
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