Published:
10 July 2003
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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2003.0480 -- Microsoft Security Bulletin MS03-023 Buffer Overrun In HTML Converter Could Allow Code Execution (Q823559) 10 July 2003 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Windows Server 2003 Windows XP Windows 2000 Windows NT 4.0 Terminal Services Windows NT 4.0 Windows Me Windows 98/98SE Publisher: Microsoft Impact: Execute Arbitrary Code/Commands Access Required: Remote CVE Names: CAN-2003-0469 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- - - - --------------------------------------------------------------- Title: Buffer Overrun In HTML Converter Could Allow Code Execution (823559) Date: 09 July 2003 Software: Microsoft(r) Windows (r) 98 Microsoft Windows 98 Second Edition Microsoft Windows Me Microsoft Windows NT 4.0 Microsoft Windows NT 4.0 Terminal Services Edition Microsoft Windows 2000 Microsoft Windows XP Microsoft Windows Server 2003 Impact: Allow an attacker to execute code of their choice Max Risk: Critical Bulletin: MS03-023 Microsoft encourages customers to review the Security Bulletins at: http://www.microsoft.com/technet/security/bulletin/MS03-023.asp http://www.microsoft.com/security/security_bulletins/ms03-023.asp - - - --------------------------------------------------------------- Issue: ====== All versions of Microsoft Windows contain support for file conversion within the operating system. This functionality allows users of Microsoft Windows to convert file formats from one to another. In particular, Microsoft Windows contains support for HTML conversion within the operating system. This functionality allows users to view, import, or save files as HTML. There is a flaw in the way the HTML converter for Microsoft Windows handles a conversion request during a cut-and-paste operation. This flaw causes a security vulnerability to exist. A specially crafted request to the HTML converter could cause the converter to fail in such a way that it could execute code in the context of the currently logged-in user. Because this functionality is used by Internet Explorer, an attacker could craft a specially formed Web page or HTML e-mail that would cause the HTML converter to run arbitrary code on a user's system. A user visiting an attacker's Web site could allow the attacker to exploit the vulnerability without any other user action. To exploit this vulnerability, the attacker would have to create a specially-formed HTML e-mail and send it to the user. Alternatively, an attacker would have to host a malicious Web site that contains a Web page designed to exploit this vulnerability. The attacker would then have to persuade a user to visit that site. Mitigating factors: ==================== - By default, Internet Explorer on Windows Server 2003 runs in Enhanced Security Configuration. This default configuration of Internet Explorer blocks automatic exploitation of this attack. If Internet Explorer Enhanced Security Configuration has been disabled, the protections put in place that prevent this vulnerability from being automatically exploited would be removed. - In the Web-based attack scenario, the attacker would have to host a Web site that contained a Web page used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site outside the HTML e-mail vector. Instead, the attacker would need to lure them there, typically by getting them to click a link that would take them to the attacker's site. - Exploiting the vulnerability would allow the attacker only the same privileges as the user. Users whose accounts are configured to have few privileges on the system would be at less risk than ones who operate with administrative privileges. Risk Rating: ============ Critical Patch Availability: =================== - A patch is available to fix this vulnerability. Please read the Security Bulletins at http://www.microsoft.com/technet/security/bulletin/ms03-023.asp http://www.microsoft.com/security/security_bulletins/ms03-023.asp for information on obtaining this patch. - - - --------------------------------------------------------------- THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. 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On call after hours for member emergencies only. -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBPwzfnih9+71yA2DNAQGRrwP/euR+mbI3nrBQDULm7ZdLREEKx+scAIon Nz/P5DBOQHEL9uW2MZT0sDvSMFG/sidHbdlI8y5yvYMijSj6kifZVaT5oQ+fix1u yTBGdJfP1N+qN5Z9oGLxkk+KsW9dLpYHRJomkTn0N6/djC9VYHphVkkXL+7AmxX3 36iknndLk/8= =rAiT -----END PGP SIGNATURE-----