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               Fedora Legacy Update Advisory

Synopsis:          Updated screen resolves security vulnerability
Advisory ID:       FLSA:1187
Issue date:        2004-01-26
Product:           Red Hat Linux
Keywords:          Security
Cross references:   
CVE Names:         CAN-2003-0972
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1. Topic:

Updated screen packages are now available that fix a security 
vulnerability which may allow privilege escalation for local users, and 
possibly remote attacks or getting control of another user's screen.

2. Relevant releases/architectures:

Red Hat Linux 7.2 - i386
Red Hat Linux 7.3 - i386
Red Hat Linux 8.0 - i386

3. Problem description:

The screen utility allows you to have multiple logins on just one
terminal. Screen is useful for users who telnet into a machine or are
connected via a dumb terminal, but want to use more than just one
login.

Timo Sirainen has reported an integer signedness error in ansi.c for GNU 
screen 4.0.1 and earlier, and 3.9.15 and earlier, which allows local 
users to execute arbitrary code via a large number of ";" (semicolon) 
characters in escape sequences, which leads to a buffer overflow. The 
Common Vulnerabilities and Exposures project (cve.mitre.org) has 
assigned the name CAN-2003-0966 to this issue.

Users of screen should update to these update packages, which contain a 
backported security patch that corrects this issue.

Fedora Legacy would like to thank Timo Sirainen for discovering and 
disclosing this issue, and Jason Rohwedder and Christian Pearce for 
providing a backported fix for Red Hat Linux 7.2, 7.3, and 8.0.

All users are advised to upgrade to these update packages, which contain 
a backported security patch that corrects 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 yum and apt.  Many 
people find this an easier way to apply updates.  To use yum issue:

yum update

or to use apt:

apt-get update; apt-get upgrade

This will start an interactive process that will result in the 
appropriate RPMs being upgraded on your system.  This assumes that you 
have yum or apt-get configured for obtaining Fedora Legacy content.  
Please visit    for directions on how 
to configure yum and apt-get.

5. Bug IDs fixed:
 
  - 1187 - screen security patch in rh7x, rh8

6. RPMs required:

Red Hat Linux 7.2:

SRPMS: 
 
i386: 
 

Red Hat Linux 7.3:

SRPMS: 
 
i386: 
 

Red Hat Linux 8.0:

SRPMS: 
 
i386: 
 

7. Verification:

SHA1 sum                                 Package Name
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194fbeb6e1871aad733966eb03525ee3fa6b736e  
7.2/updates/SRPMS/screen-3.9.9-4.legacy.src.rpm
38752ec03ec07ab125ab495910861d0317dfe095  
7.2/updates/i386/screen-3.9.9-4.legacy.i386.rpm
 
e22108165eeb8a4f2d6f078600117d2a3b5dc88d  
7.3/updates/SRPMS/screen-3.9.11-4.legacy.src.rpm
278a76f5b56d32bc983ab5dc388397c98dffe31c  
7.3/updates/i386/screen-3.9.11-4.legacy.i386.rpm
 
578b3166a0f647ac2a798ad81bdea43c9fe55c7b  
8.0/updates/SRPMS/screen-3.9.11-11.legacy.src.rpm
c1422da61421e74a5a66e5404f1fcd33134c07e8  
8.0/updates/i386/screen-3.9.11-11.legacy.i386.rpm

These packages are GPG signed by Fedora Legacy for security.  Our key is 
available from   

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 sha1sum with the following command:

    sha1sum 

8. References:
 
CVE -CVE-2003-0972 
http://marc.theaimsgroup.com/?l=bugtraq&m=106995837813873&w=2
 

9. Contact:

The Fedora Legacy security contact is <secnotice@fedoralegacy.org>. More 
project details at  

- -- 
Jesse Keating RHCE      (geek.j2solutions.net)
Fedora Legacy Team      (www.fedoralegacy.org)