OpenServer 5.0.6 OpenServer 5.0.7 : A vulnerability in TCP
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SCO Security Advisory
Subject: OpenServer 5.0.6 OpenServer 5.0.7 : A vulnerability in
TCP
Advisory number: SCOSA-2005.3
Issue date: 2005 February 28
Cross reference: sr890248 fz529385 erg712599 CAN-2004-0230
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1. Problem Description
TCP, when using a large Window Size, makes it easier for
remote attackers to guess sequence numbers and cause a
denial of service (connection loss) to persistent TCP
connections by repeatedly injecting a TCP RST packet,
especially in protocols that use long-lived connections,
such as BGP.
Paul Watson performed a statistical analysis of this attack
when the ISN is not known and has pointed out that such an
attack could be viable when specifically taking into account
the TCP Window size. He has also created a proof-of-concept
tool demonstrating the practicality of the attack.
The National Infrastructure Security Co-Ordination Center (NISCC)
has published an advisory summarizing Paul Watson's analysis in
"NISCC Vulnerability Advisory 236929."
The Common Vulnerabilities and Exposures project (cve.mitre.org)
has assigned the name CAN-2004-0230 to this issue.
2. Vulnerable Supported Versions
System Binaries
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OpenServer 5.0.6 TCP driver
OpenServer 5.0.7 TCP driver
3. Solution
The proper solution is to install the latest packages.
4. OpenServer 5.0.7
4.1 Location of Fixed Binaries
ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2005.3
4.2 Verification
MD5 (VOL.000.000) = 0f3182ee23d7bd90359d7ac0973dd44e
md5 is available for download from
ftp://ftp.sco.com/pub/security/tools
4.3 Installing Fixed Binaries
Upgrade the affected binaries with the following sequence:
1) Download the VOL* files to the /tmp directory
2) Run the custom command, specify an install from media
images, and specify the /tmp directory as the location of
the images.
5. OpenServer 5.0.6
5.1 Location of Fixed Binaries
ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2005.3
5.2 Verification
MD5 (VOL.000.000) = 0f3182ee23d7bd90359d7ac0973dd44e
md5 is available for download from
ftp://ftp.sco.com/pub/security/tools
5.3 Installing Fixed Binaries
Upgrade the affected binaries with the following sequence:
1) Download the VOL* files to the /tmp directory
2) Run the custom command, specify an install from media
images, and specify the /tmp directory as the location of
the images.
6. References
Specific references for this advisory:
http://www.uniras.gov.uk/vuls/2004/236929/index.htm
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0230
http://www.us-cert.gov/cas/techalerts/TA04-111A.html
SCO security resources:
http://www.sco.com/support/security/index.html
SCO security advisories via email
http://www.sco.com/support/forums/security.html
This security fix closes SCO incidents sr890248 fz529385
erg712599.
7. Disclaimer
SCO is not responsible for the misuse of any of the information
we provide on this website and/or through our security
advisories. Our advisories are a service to our customers
intended to promote secure installation and use of SCO
products.
8. Acknowledgments
SCO would like to thank The National Infrastructure Security
Co-Ordination Centre (NISCC), Paul Watson and Tim Newsham.
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