October 2005

ID: 00924
Ref: 864/2005
Date: 21 October 2005:09:01:34
Version: 1

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Title: Exploit code available for Snort Back Orifice Preprocessor vulnerability
Abstract: Several exploits for the Snort Back Orifice Preprocessor vulnerability have been published including remote code execution exploits that could be used to create a fast spreading worm.

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A U S C E R T A L E R T

AL-2005.0036 -- AUSCERT ALERT
Exploit code available for Snort Back Orifice Preprocessor vulnerability
21 October 2005

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AusCERT Alert Summary
---------------------

Product: Snort 2.4.0 to 2.4.2
Operating System: UNIX variants
Windows
Impact: Execute Arbitrary Code/Commands
Denial of Service
Access: Remote/Unauthenticated
CVE Names: CAN-2005-3252

Ref: ESB-2005.0830

Original Bulletin: http://www.snort.org/pub-bin/snortnews.cgi#99

OVERVIEW:

Several exploits for the Snort Back Orifice Preprocessor
vulnerability[1] have been published[2] including remote code
execution exploits that could be used to create a fast spreading worm.


IMPACT:

Should a worm be created from these exploits, local networks could
suffer noticable slow downs or complete outages. Systems could also
be affected by a malicious payload should one be included.


MITIGATION:

Users of vulnerable Snort installs should upgrade to Snort 2.4.3. If
testing time is required before an upgrade, users are encouraged to
turn off the Back Orifice Preprocessor in the mean time.

To turn off the preprocessor, do the following[3]:

1. Open 'snort.conf' with the text editor of your choice
2. Locate the line "preprocessor bo"
3. Comment out this line by preceding it with a hash (#).
The new line will look like "#preprocessor bo"
4. Save the file
5. Restart Snort


REFERENCES:

1. AusCERT ESB-2005.0830
http://www.auscert.org.au/5623
2. SANS Handler's Diary
http://isc.sans.org/diary.php?compare=1&storyid=772
3. Snort Home Page
http://www.snort.org/pub-bin/snortnews.cgi#99

AusCERT has made every effort to ensure that the information contained
in this document is accurate. However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. AusCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.

If you believe that your computer system has been compromised or attacked in
any way, we encourage you to let us know by completing the secure National IT
Incident Reporting Form at:

http://www.auscert.org.au/render.html?it=3192

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Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for member emergencies only.
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