MS03-015: IE URLMON.DLL HTTP Response Buffer Overflow Vulnerability Analysis

Vulnerability Overview Issue: Buffer overflow vulnerability in the HTTP parsing code of Internet Explorer. Location: The vulnerable code resides in URLMON.DLL. Potential Threat: Malicious users can exploit this vulnerability to execute arbitrary code on the systems of IE users. Detailed Information HTTP Protocol: The protocol used for communication between web servers and browsers. HTTP Response: An HTTP response includes web page content and some header fields, such as instructions on how to render the document to the user. Core Problem: Due to insufficient or missing input validation, when Internet Explorer receives an HTTP response with excessively long values in certain header fields, a buffer overflow occurs. Attack Scenario: A malicious response may overwrite the buffer, corrupt the return address of a subroutine, and redirect program execution to an arbitrary address. This is a classic stack overflow vulnerability, relatively easy to exploit. Attack Vectors: Attackers can inject arbitrary code when users browse a specially crafted webpage using Internet Explorer, or when using Outlook or Outlook Express to read emails. Solution Vendor Response: Microsoft became aware of the vulnerability on March 16, 2003, classified it as critical, and released an advisory and patch. Advisory and Patch: Detailed information is available at MS Official Advisory. Microsoft’s Misstatement: Microsoft claimed the vulnerability could not be exploited via email. This claim was proven incorrect. Testing confirmed that attacks are possible via Outlook and Outlook Express. No further user interaction is required; the attack does not rely on email attachments or scripts, and can be carried out using standard HTML. Acknowledgments Vulnerability Discoverer: Discovered by Jouko Pynnönen of Oy Online Solutions Ltd. (Finland), and publicly demonstrated at the "Tekninen Tietoturva" conference in Helsinki on April 25, 2004. --- From: Jouko Pynnönen

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MS03-015: IE URLMON.DLL HTTP Response Buffer Overflow Vulnerability Analysis