Snort mailing list archives

Re: Fixes and Mitigation Instructions Available for Snort Back Orifice Vulnerability


From: Sam Evans <wintrmte () gmail com>
Date: Tue, 18 Oct 2005 18:31:23 -0600

Thanks, like I said, I think the problem was on my end (and it was).



On 10/18/05, Ron Jenkins <rjenkins () dibr net> wrote:

I see it too.

-----Original Message-----
From: snort-users-admin () lists sourceforge net
[mailto:snort-users-admin () lists sourceforge net] On Behalf Of Jennifer
Steffens
Sent: Tuesday, October 18, 2005 5:31 PM
To: Sam Evans
Cc: snort-users @ lists. sourceforge. net
Subject: Re: [Snort-users] Fixes and Mitigation Instructions Available
for Snort Back Orifice Vulnerability

Sam,

Can you try refreshing the page? The 2.4.3 version is there for me. The
actual link is http://www.snort.org/dl/current/snort-2.4.3.tar.gz.

Thanks,
Jennifer

Sam Evans wrote:
Jennifer,

I might be missing something, but when I click the
http://www.snort.org/dl/ link all I see is the 2.4.2 version, not the
2.4.3.

Thanks,
Sam



On 10/18/05, *Jennifer Steffens* <jennifer.steffens () sourcefire com
<mailto:jennifer.steffens () sourcefire com>> wrote:

Subject: Fix and Mitigation Available for Snort Vulnerability

The Sourcefire Vulnerability Research Team (VRT) has learned of a
vulnerability in Snort v2.4.0 and higher. Users are only
vulnerable if
the Back Orifice preprocessor is enabled. Snort v2.4.3 has been
released
to correct the issue and detailed instructions for mitigating the
issue
by disabling the Back Orifice preprocessor are below.


Snort v2.4.3

In addition to fixing the vulnerability, this version includes a
mechanism to detect exploits against vulnerable sensors and,
optionally
for inline sensors, drop the offending traffic. These features
enable a
phased approach to upgrading while protecting unpatched sensors.
Detection capabilities are part of the new preprocessor and
therefore
are available to all users regardless of subscription status.

In addition to the source tarball, postgres, mysql and plain RPMs
and a
win32 installer are available at http://www.snort.org/dl. Please
remember that updated rules are only included in major releases.
For
updated rules, visit http://www.snort.org/rules/.


Mitigation Instructions:

The Back Orifice preprocessor can be disabled by commenting out
the line
"preprocessor bo" in snort.conf. This can be done in any text
editor
using the following procedure:

1. Locate the line "preprocessor bo"
2. Comment out this line by preceding it with a hash (#). The new
line
will look like "#preprocessor bo"
3. Save the file
4. Restart snort


Background:

On Thursday, October 13th Sourcefire was contacted by USCERT with
news
of a vulnerability in Snort. We used the subsequent days to verify
the
vulnerability and to prepare mitigation strategies and the
software
updates necessary to fix the vulnerability for both Sourcefire
customers
and Snort users. While it cannot be said that no other problems
will
ever be found in the Snort code base, we can state that we will
redouble
our efforts to ensure the security of the system so many people
have
come to rely on for the detection of network-based threats.
Sourcefire
will also continue to work with the most sophisticated testing
facilities in the industry to assure that every reasonable step is
being
taken to provide the most secure code base possible.


Technical Details:
The Back Orifice preprocessor contains a stack-based buffer
overflow.
This vulnerability could be leveraged by an attacker to execute
code
remotely on a Snort sensor where the Back Orifice preprocessor is
enabled. However, there are a number of factors that make remote
code
execution difficult to achieve across different builds of Snort on
different platforms, even on the same platform with different
compiler
versions, and it is more likely that an attacker could use the
vulnerability as a denial of service attack.


If you have any questions, please let us know at
snort-team () sourcefire com <mailto:snort-team () sourcefire com>

Thanks,
Jennifer


--
Jennifer S. Steffens
Director, Snort Product Management | Sourcefire, Inc.
W: 410.423.1930 | C: 202.409.7707
www.sourcefire.com <http://www.sourcefire.com> <
http://www.sourcefire.com> | www.snort.org <http://www.snort.org>
<http://www.snort.org>


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