Red Hat Linux Advisory: stunnel

Red Hat Security Advisory

1. Topic:

Updated stunnel packages are now available for Red Hat Linux
7.1, 7.2, 7.3, and 8.0. These updates correct a potential
vulnerability in stunnel’s signal handling.

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

3. Problem description:

Stunnel is a wrapper for network connections. It can be used to
tunnel an unencrypted network connection over a secure connection
(encrypted using SSL or TLS) or to provide a secure means of
connecting to services that do not natively support encryption.

When configured to listen for incoming connections (instead of
being invoked by xinetd), stunnel can be configured to either start
a thread or a child process to handle each new connection. If
Stunnel is configured to start a new child process to handle each
connection, it will receive a SIGCHLD signal when that child
exits.

Stunnel versions prior to 4.04 would perform tasks in the
SIGCHLD signal handler which, if interrupted by another SIGCHLD
signal, could be unsafe. This could lead to a denial of
service.

All users are urged to upgrade to these errata packages, which
modify stunnel’s signal handler so that it is not vulnerable to
this issue.

NOTE: After upgrading, any instances of stunnel configured to
run in daemon mode should be restarted, and any active network
connections that are currently being serviced by stunnel should be
terminated and reestablished.

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. Bug IDs fixed (http://bugzilla.redhat.com/bugzilla
for more info):

82325 – stunnel security errata required

6. RPMs required:

Red Hat Linux 7.1:

SRPMS:

ftp://updates.redhat.com/7.1/en/os/SRPMS/stunnel-3.22-5.7.1.src.rpm

i386:

ftp://updates.redhat.com/7.1/en/os/i386/stunnel-3.22-5.7.1.i386.rpm

Red Hat Linux 7.2:

SRPMS:

ftp://updates.redhat.com/7.2/en/os/SRPMS/stunnel-3.22-5.7.3.src.rpm

i386:

ftp://updates.redhat.com/7.2/en/os/i386/stunnel-3.22-5.7.3.i386.rpm

ia64:

ftp://updates.redhat.com/7.2/en/os/ia64/stunnel-3.22-5.7.3.ia64.rpm

Red Hat Linux 7.3:

SRPMS:

ftp://updates.redhat.com/7.3/en/os/SRPMS/stunnel-3.22-5.7.3.src.rpm

i386:

ftp://updates.redhat.com/7.3/en/os/i386/stunnel-3.22-5.7.3.i386.rpm

Red Hat Linux 8.0:

SRPMS:

ftp://updates.redhat.com/8.0/en/os/SRPMS/stunnel-3.22-5.8.0.src.rpm

i386:

ftp://updates.redhat.com/8.0/en/os/i386/stunnel-3.22-5.8.0.i386.rpm

7. Verification:

MD5 sum Package Name

e20a6bcf06735897d4b9f7a05b9ded3f
7.1/en/os/SRPMS/stunnel-3.22-5.7.1.src.rpm
38a38be900e55173493db34a1d0fdddd
7.1/en/os/i386/stunnel-3.22-5.7.1.i386.rpm
d74e461c13ccb49a48bac85560b40287
7.2/en/os/SRPMS/stunnel-3.22-5.7.3.src.rpm
bc60108d725ce1b88bfdc16db0b9ee6f
7.2/en/os/i386/stunnel-3.22-5.7.3.i386.rpm
f017a9e4373a8478342961e430c8405f
7.2/en/os/ia64/stunnel-3.22-5.7.3.ia64.rpm
d74e461c13ccb49a48bac85560b40287
7.3/en/os/SRPMS/stunnel-3.22-5.7.3.src.rpm
bc60108d725ce1b88bfdc16db0b9ee6f
7.3/en/os/i386/stunnel-3.22-5.7.3.i386.rpm
37e3c19c87b1c47a3a503823ce19a687
8.0/en/os/SRPMS/stunnel-3.22-5.8.0.src.rpm
10a5bac0cf90d31b6db4b49abc74ca4b
8.0/en/os/i386/stunnel-3.22-5.8.0.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 <filename>

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 <filename>

8. References:

http://marc.theaimsgroup.com/?l=stunnel-users&m=103600188215117

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2002-1563

9. Contact:

The Red Hat security contact is <[email protected]>. More
contact details at http://www.redhat.com/solutions/security/news/contact.html

Copyright 2003 Red Hat, Inc.