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
        ----------------------------------------------------------------------
        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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