-----BEGIN PGP SIGNED MESSAGE----- Internet Security Systems Security Advisory November 12, 2001 Multi-Vendor Buffer Overflow Vulnerability in CDE Subprocess Control Service Synopsis: Internet Security Systems (ISS) X-Force has discovered a buffer overflow in the Subprocess Control Server (dtspcd) in all Unix variants running CDE (Common Desktop Environment) system. The vulnerability in the dtspcd daemon may allow remote attackers to execute arbitrary commands on a target system with super user privilege. Affected Versions: Many Unix vendors are affected by this vulnerability. ISS X-Force has been working with CERT on this issue. Please refer to the CERT advisory at the following address for the current list of vulnerable versions: http://www.cert.org/advisories/CA-2001-31.html Description: CDE is the default X-Windows GUI environment shipped with newer versions of Sun Solaris and many other Unix variants. The Subprocess Control Server daemon is not intended to be run by normal users and is spawned by other components within the CDE system. Dtspcd is started by the Internet services daemon (inetd) when a CDE client attempts to create a process on the daemon’s host. A buffer overflow condition exists in the connection negotiation routine within dtpscd. A remote attacker can generate a specially crafted CDE client request to take advantage of the flaw and overflow exploit code onto the heap. The attacker can use this exploit code to execute arbitrary commands on the target system. The Subprocess Control Server daemon is enabled by default on all operating systems with CDE installed. This process is run by the "root" user and accepts remote connections by default. Recommendations: This advisory was tentatively scheduled for release in December 2001. The issue was made public in the following announcement before most vendors were able to make patches available: ftp://stage.caldera.com/pub/security/openunix/CSSA-2001-SCO.30/ ISS X-Force encourages all affected users to check with your individual vendors for patch availability. Users should take steps to disable or limit access to the vulnerable service until patches are made available. ISS RealSecure Network Sensor customers can configure a Connection Event for port 6112 to detect potential attacks. For more information on configuring Connection Events, refer to the RealSecure 6.0 Network Sensor Policy Guide, or the RealSecure 5.x Network Sensor User Guide. ISS RealSecure Server Sensor customers can configure Server Sensor to block access attempts to the dtspc port. The following steps describe how to add a Firecell rule to RealSecure Server Sensor (Solaris and Linux) to block access attempts to the dtspc port. X-Force recommends that administrators investigate the implications of blocking dtspc in their environments before applying this rule. 1. Open the server sensor policy to which you want to add this signature. 2. Select the Protect tab, open the Protect folder, and then open the Firecell folder. 3. Select the TCP Inbound section. 4. Click Add to create a new signature. 5. Type a name for the firecell signature, e.g. Block_dtspcd, and then click OK. The new signature is added to the policy in the TCP Inbound section. 6. Select the signature that you just created. The properties of the signature appear in the right pane. 7. Set the priority of the event in the Priority box. 8. In the Port number field, type 6112. 9. In the IP address field, select ANY ADDRESS. 10. In the Actions section, select Action (1) In the range of IP addresses, drop the packet and generate the responses. 11. In the Response section, select the responses you want the sensor to take when a match to this signature occurs. 12. Save and apply the policy to the sensor. ISS X-Force will provide specific detection and assessment support for this vulnerability in upcoming X-Press Updates for RealSecure Network Sensor and Internet Scanner. ISS will also provide detection support in an upcoming signature update for BlackICE products. Additional Information: The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2001-0803 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. http://www.cert.org/advisories/CA-2001-31.html http://www.kb.cert.org/vuls/id/172583 http://xforce.iss.net/static/7396.php Credits: This vulnerability was discovered and researched by Chris Spencer of the ISS X-Force. Internet Security Systems would like to thank CERT for their response and handling of this vulnerability. ______ About Internet Security Systems (ISS) Internet Security Systems is a leading global provider of security management solutions for the Internet, protecting digital assets and ensuring safe and uninterrupted e-business. With its industry-leading intrusion detection and vulnerability assessment, remote managed security services, and strategic consulting and education offerings, ISS is a trusted security provider to more than 8,000 customers worldwide including 21 of the 25 largest U.S. commercial banks and the top 10 U.S. telecommunications companies. Founded in 1994, ISS is headquartered in Atlanta, GA, with additional offices throughout North America and international operations in Asia, Australia, Europe, Latin America and the Middle East. For more information, visit the Internet Security Systems web site at www.iss.net or call 888-901-7477. Copyright (c) 2001 Internet Security Systems, Inc. All rights reserved worldwide. Permission is hereby granted for the redistribution of this Alert electronically. It is not to be edited in any way without express consent of the X-Force. If you wish to reprint the whole or any part of this Alert in any other medium excluding electronic medium, please e-mail xforceat_private for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk. X-Force PGP Key available at: http://xforce.iss.net/sensitive.php as well as on MIT's PGP key server and PGP.com's key server. Please send suggestions, updates, and comments to: X-Force xforceat_private of Internet Security Systems, Inc. -----BEGIN PGP SIGNATURE----- Version: 2.6.3a Charset: noconv iQCVAwUBO/A8DjRfJiV99eG9AQFXUAQAv3d2rIFez1izRytZAwtVrNd5BoPtqBXI hUnt+gBxHmLcitRRbIgfq0ajfjy5nGX/ZC0wW/LYJHVgJfjhCJqC6AZYGv9QWt37 G6G5zFmurmagprNMAe2cWfQoHoVIuHmMYVMqu8p90N/pAfjUGfPdS1umWN6zJKVK 1/FFFMutPtk= =2mgO -----END PGP SIGNATURE-----
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