(Turbo Linux Releases Fix) Re: Weaknesses in SSH Protocols Can Facilitate Attacks Through Passive Monitoring of Protocol Traffic
SecurityTracker Alert ID: 1001596|
SecurityTracker URL: http://securitytracker.com/id/1001596
(Links to External Site)
Date: May 23 2001
Disclosure of authentication information, Disclosure of system information|
Fix Available: Yes Vendor Confirmed: Yes |
It was reported last week that several weaknesses exist in various implementations of SSH (Secure Shell) protocols. When exploited, these vulnerabilities let an attacker obtain sensitive information by passively monitoring encrypted SSH sessions that can later be used to facilitate attacks. This could include speeding up brute-force attacks on passwords, including the initial login password and other passwords appearing in interactive SSH sessions.|
Version 1 of the SSH protocol generally exposes the exact lengths of login passwords used with password authentication. The SSH-2 protocol doesn't reveal as much information, but still presents a range of possible password lengths.
Additional weaknesses reportedly allow for detection of when a password is entered during an interactive SSH session and detection of the timing of the keying, which may expose the likelihood of possible characters in each position of a password. It is also reportedly possible to determine the lengths of shell commands.
For details, please read the source message.
An attacker that is monitoring SSH traffic could obtain sensitive information that can later be used to facilitate attacks. This could include speeding up brute-force attacks on passwords, including the initial login password and other passwords appearing in interactive SSH sessions, such as those used with su(1) and Cisco IOS "enable" passwords.|
Turbo Linux has released a fix. See the Source Message for the Turbo Linux advisory.|
Vendor URL: www.openssh.org (Links to External Site)
Authentication error, Randomization error|
|Underlying OS: Linux (Turbo Linux)|
This archive entry is a follow-up to the message listed below.|
Source Message Contents
Subject: [TL-Security-Announce] TLSA2001021 openssh-2.5.2p2-2|
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Turbolinux Security Announcement
Vulnerable Packages: All Turbolinux versions prior to 2.5.2p2-2
Date: 05/17/2001 5:00 PDT
Affected Turbolinux platforms: TL Server 6.5
Turbolinux Advisory ID#: TLSA2001021
Credits: Solar Designer < firstname.lastname@example.org >
Dug Song <email@example.com>
Markus Friedl and Theo de Raadt of OpenSSH
Simon Tatham (PuTTY), and Niels Mller (LSH)
Several security holes were discovered in the package mentioned above.
Please update the packages in your installation as soon as possible.
1. Problem Summary
Several weaknesses in the SSH protocol have been detected. To capitalize on them, an
attacker must have the means to sniff, or monitor, network traffic between one or more
SSH clients and servers. Exploiting these weaknesses would enable an attacker to determine
passwords and shell commands more quickly during passive monitoring of password authenti-
cation and interactive ssh sessions.
The weaknesses in the SSH protocol include revealing an approximate, or, in the case
of SSH1, an exact length of a password, or shell command. It is also possible to gather
timing information, which can expose the likelihood of possible characters in each posi-
tion of a password. Using compression in an attempt to "randomize" the length of pass-
words does not help much since the size of the compressed data packets depends on the con-
tents of the packets.
Update the packages from our ftp server by using the following command:
rpm -Uvh ftp_path_to_filename
Where ftp_path_to_filename is the following:
The source RPM can be downloaded here:
**Note: You must rebuild and install the RPM if you choose to download
and install the SRPM. Simply installing the SRPM alone WILL NOT CLOSE
THE SECURITY HOLE.
Please verify the MD5 checksums of the updates before you install:
MD5 sum Package Name
These packages are GPG signed by Turbolinux for security. Our key
is available here:
To verify a package, use the following command:
rpm --checksig name_of_rpm
To examine only the md5sum, use the following command:
**Note: Checking GPG keys requires RPM 3.0 or higher.
You can find more updates on our ftp server:
for TL6.x Workstation and Server security updates
Our webpage for security announcements:
If you want to report vulnerabilities, please contact:
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Subscribe at http://www.turbolinux.com/mailman/listinfo/tl-security
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