RedHat7: 'openssh' vulnerability
Posted by LinuxSecurity.com Team   
RedHat Linux An OpenSSH client will do agent or X11 forwarding at the request of a server, even if the user has not requested that it be done.

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                   Red Hat, Inc. Security Advisory

Synopsis:          Updated openssh packages available for Red Hat Linux 7
Advisory ID:       RHSA-2000:111-04
Issue date:        2000-11-20
Updated on:        2000-11-27
Product:           Red Hat Linux
Keywords:          openssh malicious server port forwarding
Cross references:  N/A
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1. Topic:

Updated openssh packages are now available for Red Hat Linux 7.

2000-11-27: Added packages for Red Hat Linux 7 for Alpha

2. Relevant releases/architectures:

Red Hat Linux 7.0 - i386, alpha

3. Problem description:

An OpenSSH client will do agent or X11 forwarding at the request of a
server, even if the user has not requested that it be done.  A malicious
server can exploit this vulnerability to gain access to the user's display.

4. Solution:

For each RPM for your particular architecture, run:



rpm -Fvh [filename]



where filename is the name of the RPM.

5. Bug IDs fixed  (http://bugzilla.Red Hat.com/bugzilla for more info):

18598 - ssh-keygen -l does not work for dsa keys
20805 - Hostile servers can force OpenSSH clients to do agent or X11 forwarding
20884 - openssh-2.3.0p1 doesn't include /etc/ssh/primes


6. RPMs required:

Red Hat Linux 7.0:

alpha: 
ftp://updates.Red Hat.com/7.0/alpha/openssh-2.3.0p1-4.alpha.rpm 
ftp://updates.Red Hat.com/7.0/alpha/openssh-clients-2.3.0p1-4.alpha.rpm 
ftp://updates.Red Hat.com/7.0/alpha/openssh-server-2.3.0p1-4.alpha.rpm 
ftp://updates.Red Hat.com/7.0/alpha/openssh-askpass-2.3.0p1-4.alpha.rpm 
ftp://updates.Red Hat.com/7.0/alpha/openssh-askpass-gnome-2.3.0p1-4.alpha.rpm

i386: 
ftp://updates.Red Hat.com/7.0/i386/openssh-2.3.0p1-4.i386.rpm 
ftp://updates.Red Hat.com/7.0/i386/openssh-clients-2.3.0p1-4.i386.rpm 
ftp://updates.Red Hat.com/7.0/i386/openssh-server-2.3.0p1-4.i386.rpm 
ftp://updates.Red Hat.com/7.0/i386/openssh-askpass-2.3.0p1-4.i386.rpm 
ftp://updates.Red Hat.com/7.0/i386/openssh-askpass-gnome-2.3.0p1-4.i386.rpm

sources: 
ftp://updates.Red Hat.com/7.0/SRPMS/openssh-2.3.0p1-4.src.rpm

7. Verification:

MD5 sum                           Package Name
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d564b593cce6c1afaa02a11004ef6cf7  7.0/SRPMS/openssh-2.3.0p1-4.src.rpm
cfa7b84d1389e921d11cd93888014bbe  7.0/alpha/openssh-2.3.0p1-4.alpha.rpm
59464df875127cc44ca1976db62bb977  7.0/alpha/openssh-askpass-2.3.0p1-4.alpha.rpm
957467291fc0067d70bef99c88401dcf
7.0/alpha/openssh-askpass-gnome-2.3.0p1-4.alpha.rpm
da26d6a308c2c3c79f56eec077bce664  7.0/alpha/openssh-clients-2.3.0p1-4.alpha.rpm
5e4951bc163601aad8733011933d79db  7.0/alpha/openssh-server-2.3.0p1-4.alpha.rpm
973c033bd3cf3e3641f7fb9d172baf5a  7.0/i386/openssh-2.3.0p1-4.i386.rpm
ead1cc84519f5a6fa0233ce8d3237457  7.0/i386/openssh-askpass-2.3.0p1-4.i386.rpm
d426ff6c55181f8ccbea6e2f7a307b99  7.0/i386/openssh-askpass-gnome-2.3.0p1-4.i386.rpm
51fe082e6830e461a900000e2884cb14  7.0/i386/openssh-clients-2.3.0p1-4.i386.rpm
dd9bb3271403162202599d3cd8b9a22e  7.0/i386/openssh-server-2.3.0p1-4.i386.rpm

These packages are GPG signed by Red Hat, Inc. for security.  Our key
is available at:
     http://www.Red Hat.com/corp/contact.html

You can verify each package with the following command:
    rpm --checksig  

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

8. References:
 
http://www.openbsd.org/errata27.html#sshforwarding


Copyright(c) 2000 Red Hat, Inc.