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                Caldera International, Inc. Security Advisory 

Subject: Open UNIX 8.0.0 UnixWare 7.1.1 : ftpd allows data connection hijacking via PASV mode 
Advisory number: CSSA-2002-SCO.23 
Issue date: 2002 May 30 
Cross reference: 
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1. Problem Description 

        In FTP PASV mode, the client makes a control connection to the 
        FTP server (typically port 21/tcp) and requests a PASV data 
        connection. The server responds by listening for client 
        connections on a specified port number, which is supplied to 
        the client via the control connection. If an attacker can make 
        a connection to the listening port before the client connects, 
        the server will transmit the data to the attacker instead of 
        the client. 

        To exploit this vulnerability, the attacker must intercept or 
        guess the port number that the server will use, then make its 
        connection attempt before the client establishes a data 
        connection. If the server chooses port numbers using an easily 
        identifiable pattern (such as incrementally), this 
        vulnerability is trivial to exploit. 

2. Vulnerable Supported Versions 

        System Binaries 
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        Open UNIX 8.0.0 /usr/sbin/in.ftpd 
        UnixWare 7.1.1 /usr/sbin/in.ftpd 

3. Solution 

        The proper solution is to install the latest packages. 

4. Open UNIX 8.0.0 

        4.1 Location of Fixed Binaries 

        ftp://stage.caldera.com/pub/security/openunix/CSSA-2002-SCO.23 

        4.2 Verification 

        MD5 (erg501602b.pkg.Z) = e25467ff65349f5f388698fdd39161b5 

        md5 is available for download from 
                ftp://stage.caldera.com/pub/security/tools/ 

        4.3 Installing Fixed Binaries 

        Upgrade the affected binaries with the following commands: 

        Download erg501602b.pkg.Z to the /var/spool/pkg directory 

        # uncompress /var/spool/pkg/erg501602b.pkg.Z 
        # pkgadd -d /var/spool/pkg/erg501602b.pkg 

5. UnixWare 7.1.1 

        5.1 Location of Fixed Binaries 

        ftp://stage.caldera.com/pub/security/openunix/CSSA-2002-SCO.23 

        5.2 Verification 

        MD5 (erg501602b.pkg.Z) = e25467ff65349f5f388698fdd39161b5 

        md5 is available for download from 
                ftp://stage.caldera.com/pub/security/tools/ 

        5.3 Installing Fixed Binaries 

        Upgrade the affected binaries with the following commands: 

        Download erg501602b.pkg.Z to the /var/spool/pkg directory 

        # uncompress /var/spool/pkg/erg501602b.pkg.Z 
        # pkgadd -d /var/spool/pkg/erg501602b.pkg 

6. References 

        Specific references for this advisory: 
                http://www.kb.cert.org/vuls/id/2558 

        Caldera UNIX security resources: 
                http://stage.caldera.com/support/security/ 

        Caldera OpenLinux security resources: 
                http://www.caldera.com/support/security/index.html 

        This security fix closes Caldera incidents sr863902, fz520882, 
        erg501602. 

7. Disclaimer 

        Caldera International, Inc. 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 Caldera products. 

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