iDefense Security Advisory 10.17.06: Opera Software Opera Web Browser URL Parsing Heap Overflow Vulnerability


Opera Software Opera Web Browser URL Parsing Heap Overflow Vulnerability iDefense Security Advisory 10.17.06 http://www.idefense.com/intelligence/vulnerabilities/ Oct 17, 2006 I. BACKGROUND Opera is a cross-platform web browser. More information is available from http://www.opera.com/ II. DESCRIPTION Remote exploitation of a heap overflow vulnerability within version 9 of Opera Software's Opera Web browser could allow an attacker to execute arbitrary code on the affected host. A flaw exists within Opera when parsing a tag that contains a URL. A heap buffer with a constant size of 256 bytes is allocated to store the URL, and the tag's URL is copied into this buffer without sufficient bounds checking of its length. The vulnerable code would look something like this in C/C++: char *local_url = malloc(256); strcpy(local_url, tag_url); This URL can be inserted into any tag, such as an iframe. The range of characters that can be used to overflow the buffer is limited. III. ANALYSIS Successful remote exploitation allows an attacker to execute arbitrary code with the privileges of the logged in user. A failed exploitation attempt may result in the browser crashing. The attacker would first need to construct a website containing the malicious tag and trick the vulnerable user into visiting the site. This would trigger the vulnerability and allow the code to execute with the privileges of the local user. The range of characters available does not make this vulnerability significantly more difficult to exploit. Through the use of JavaScript or large compressed image files the attacker can have nearly complete control of the heap. IV. DETECTION iDefense Labs has confirmed Opera versions 9.0 and 9.01 on both Windows and Linux are vulnerable. Version 8 is not vulnerable. V. WORKAROUND iDefense is currently unaware of any effective workarounds for this vulnerability. VI. VENDOR RESPONSE Opera has addressed this vulnerability with version 9.02 of the Opera Web Browser. More information can be found in Opera's advisory at http://www.opera.com/support/search/supsearch.dml?index=848. VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-4819 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 09/15/2006 Initial vendor notification 09/29/2006 Initial vendor response 10/17/2006 Coordinated 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 © 2006 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.