Macromedia JRun 4 Web Server URL Parsing Buffer Overflow Vulnerability iDefense Security Advisory 12.21.05 http://www.idefense.com/intelligence/vulnerabilities/display.php?id=360 December 21, 2005 I. BACKGROUND Macromedia JRun 4 is an application server used for developing and deploying Java based applications. More information can be found at the following URL: http://www.macromedia.com/software/jrun/ II. DESCRIPTION Remote exploitation of a buffer overflow vulnerability in Adobe Inc.'s JRun 4 may allow attackers to execute arbitrary code or cause a denial of service condition. The vulnerability exists within the JRun web server, specifically in the handling of long request strings. In certain configurations, when a long (approximately 64k) URL is supplied, a stack-based overflow occurs potentially allowing the execution of arbitrary code. In testing performed by iDefense Labs, it was possible to overwrite the saved return address on the stack with remotely supplied values (converted into 'wide characters' by the server). III. ANALYSIS Successful exploitation may allow remote attackers to execute arbitrary code with Local System privileges. The supplied JRun web server must be active for the attack vector to exist. It is not recommended to use the JRun web server component in production systems, as the installer mentions that it should be used for development only. As the service restarts after each crash, it is possible to make multiple attempts to exploit this issue, and each time restart from a 'clean' state. Although this vulnerability allows a stack overwrite, it may be more difficult to exploit due the input string being converted into a 'wide character' version of the str input, by placing a null byte between each character. While this does not necessarily prevent exploitation, it does increase the complexity of developing an exploit. Exploitation of this vulnerability may allow a remote attacker to execute code on the affected system as Local System, allowing complete compromise, or cause a denial of service against the affected system, preventing legitimate use. IV. DETECTION This vulnerability was confirmed by the vendor to affect the JRun 4 webserver server prior to the JRun 4 Updater 5 release in March of 2005. V. WORKAROUND The JRun documentation suggests that the JRun Web Server should not be used in a production environment. In a development environment, the JRun server should not accept connections from outside of the development network. VI. VENDOR RESPONSE Adobe has reported that this issue was resolved in the JRun 4 Updater 5 release in March 2005. The following security advisory was released on December 15, 2005: http://www.macromedia.com/devnet/security/security_zone/mpsb05-13.html VII. CVE INFORMATION A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet. VIII. DISCLOSURE TIMELINE 08/25/2004 Initial vendor notification 08/31/2004 Initial vendor response 12/21/2005 Public disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. Get paid for vulnerability research http://www.idefense.com/methodology/vulnerability/vcp.php Free tools, research and upcoming events http://labs.idefense.com X. LEGAL NOTICES Copyright © 2005 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 (at) idefense (dot) com [email concealed] 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.