NSFOCUS Security Advisory (SA2006-08) Microsoft IE6 urlmon.dll Long URL Buffer Overflow Vulnerability Release Date: 2006-08-25 CVE ID: CVE-2006-3869 http://www.nsfocus.com/english/homepage/research/0608.htm Affected systems & software =================== Internet Explorer 6 SP1 with MS06-042 - Microsoft Windows XP SP1 - Microsoft Windows 2000 SP4 Unaffected systems & software =================== Summary ========= NSFocus Security Team discovered a buffer overflow in IE 6.0SP1 which allows remote code execution via an over-long URL. Description ============ Security Bulletin MS06-042 released by Microsoft on August 8th, 2006 fixed multiple vulnerabilities, but the update for IE 6 introduced a new vulnerability. When visiting websites with HTTP/1.1 protocol and data compression enabled, a buffer overflow might occur if an over-long URL is passed to IE 6. This overflow arises due to an incorrect call to function lstrncpyA, possibly resulting in heap data structure corruption. Carefully crafted data might lead to arbitrary code execution. Attackers might craft a malicious WEB page and allure users to visit it in order to run arbitrary code with the users' privilege. If the user is the administrator, the attacker might gain complete control over the system. Attackers might host malicious web servers of their own, or exploit certain servers that enable HTTP/1.1 protocol and data compression in order to launch attacks. Workaround ============= * Temporarily disable HTTP 1.1 support in IE. Vendor Status ============== 2006.08.10 Informed the vendor 2006.08.17 Vendor confirmed the vulnerability 2006.08.24 Microsoft released related patch and re-released MS06-042. Detailed Microsoft Security Bulletin is available at: http://www.microsoft.com/technet/security/bulletin/MS06-042.mspx Additional Information ======================== The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-3869 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. Candidates may change significantly before they become official CVE entries. Acknowledgment =============== Hu Qianwei of NSFocus Security Team found the vulnerability. DISCLAIMS ========== THE INFORMATION PROVIDED IS RELEASED BY NSFOCUS "AS IS" WITHOUT WARRANTY OF ANY KIND. NSFOCUS DISCLAIMS ALL WARRANTIES, EITHER EXPRESSED OR IMPLIED, EXCEPT FOR THE WARRANTIES OF MERCHANTABILITY. IN NO EVENT SHALL NSFOCUS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF NSFOCUS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. DISTRIBUTION OR REPRODUCTION OF THE INFORMATION IS PROVIDED THAT THE ADVISORY IS NOT MODIFIED IN ANY WAY. Copyright 1999-2006 NSFOCUS. All Rights Reserved. Terms of use. NSFOCUS Security Team NSFOCUS INFORMATION TECHNOLOGY CO.,LTD (http://www.nsfocus.com) PGP Key: http://www.nsfocus.com/homepage/research/pgpkey.asc Key fingerprint = F8F2 F5D1 EF74 E08C 02FE 1B90 D7BF 7877 C6A6 F6DA