RealNetworks Helix Universal Server Denial of Service Vulnerability iDEFENSE Security Advisory 04.15.04 http://www.idefense.com/application/poi/display?type=vulnerabilities February 15, 2004 I. BACKGROUND RealNetworks Helix Universal Server is a universal digital media delivery platform with industry leading performance, integrated content distribution and Web services support. More information is available at http://www.realnetworks.com. II. DESCRIPTION Remote exploitation of a denial of service (DoS) vulnerability in RealNetworks, Inc.'s Helix Universal Server could allow an attacker to restart and potentially disable the server. The problem specifically exists in the handling of specially crafted GET requests. The following sample requests will cause a null pointer dereference, thereby causing the application to crash. $ echo -e "GET_PARAMETER / RTSP/1.0\n\n" | nc -v localhost 554 $ echo -e "DESCRIBE / RTSP/1.0\nSession:\n\n" | nc -v localhost 554 If the server was started with specific options such as '--no-crash-avoidance' or '--no-auto-restart', which is not the case in the default installation, then the server will become inaccessible upon receipt of the malicious requests. III. ANALYSIS Any unauthenticated remote attacker can exploit this vulnerability to crash an affected server, thereby preventing legitimate usage. Exploit code for this issue does not exist but is not necessary as the issue is trivially exploited. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in versions 9.0.2 for Linux and version 9.0.1 for Windows. V. WORKAROUND Ensure that the server options '--no-crash-avoidance' and '--no-auto-restart' are not enabled. VI. VENDOR RESPONSE "Both issues have been secured in the 9.03 release of the server." VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2004-0389 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE December 8, 2003 Exploit acquired by iDEFENSE January 24, 2004 iDEFENSE clients notified January 26, 2004 Initial vendor notification April 15, 2004 Public disclosure IX. CREDIT Anonymous submission Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp X. LEGAL NOTICES Copyright (c) 2004 iDEFENSE, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDEFENSE. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information. _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
