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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2002.111 -- Microsoft Security Bulletin MS02-013 Java Applet Can Redirect Browser Traffic 5 March 2002 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Microsoft Virtual Machine for IE 4.x and 5.x Vendor: Microsoft Operating System: Windows Impact: Access Privileged Data Provide Misleading Information Access Required: Remote - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- - - ---------------------------------------------------------------------- Title: Java Applet Can Redirect Browser Traffic Date: 04 March 2002 Software: Microsoft Virtual Machine Impact: Information Disclosure Max Risk: Critical Bulletin: MS02-013 Microsoft encourages customers to review the Security Bulletin at: http://www.microsoft.com/technet/security/bulletin/MS02-013.asp. - - ---------------------------------------------------------------------- Issue: ====== The Microsoft VM is a virtual machine for the Win32 operating environment. It runs atop Microsoft Windows 95, Microsoft Windows 98, ME, Windows NT 4.0 , Windows 2000 and Windows XP. It ships as part of Windows 98, ME, and Windows 2000 and also as part of Internet Explorer 5.5 and earlier. The version of the Microsoft VM that ships with Internet Explorer version 4.x and 5.x contains a flaw affecting how Java requests for proxy resources are handled. A malicious Java applet could exploit this flaw to re-direct web traffic once it has left the proxy server to a destination of the attacker's choice. An attacker could use this flaw to send a user's Internet session to a system of his own control, without the user being aware of this. The attacker could then forward the information on to the intended destination, giving the appearance that the session was behaving normally. The attacker could then send his own malicious response, making it seem to come from the intended destination, or could discard the session information, creating the impression of a denial of service. Additionally, the attacker could capture and save the user's session information. This could enable him to execute a replay attack or to search for sensitive information such as user names or passwords. A system is only vulnerable if IE is used in conjunction with a proxy server. Users whose browsers are not behind a proxy server are not vulnerable to this vulnerability. However, those users would be vulnerable if they changed their browser to use a proxy server at a later date. Mitigating Factors: ==================== - The vulnerability only affects configurations that utilize a proxy server. Customers who are not using a proxy server are not at risk from this vulnerability. - Best practices strongly recommend using SSL to encrypt sensitive information such as user names, passwords and credit card numbers. If this has been done, sensitive information will be protected from examination and disclosure by an attacker exploiting this vulnerability. Risk Rating: ============ - Internet systems: Moderate - Intranet systems: Moderate - Client systems: Critical Patch Availability: =================== - A patch is available to fix this vulnerability. Please read the Security Bulletin at http://www.microsoft.com/technet/security/bulletin/ms02-013.asp for information on obtaining this patch. Acknowledgment: =============== - Harmen van der Wal (http://www.xs4all.nl/~harmwal/) - - --------------------------------------------------------------------- THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. 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If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to use any or all of this information is the responsibility of each user or organisation, and should be done so in accordance with site policies and procedures. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the original authors to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/Information/advisories.html If you believe that your system has been compromised, contact AusCERT or your representative in FIRST (Forum of Incident Response and Security Teams). Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBPIShvCh9+71yA2DNAQFPNAP+Ja2CbythqtXgBCIyBIGr+jDY6U1o7Err a4SjSneJf46ya8EUfRHefb6okzItY9U0OUSdFpwziRjD6Ssj6zdumQDDxkMC8wFr 5SkEgr2Q7g1vghC84otlkxVVaK6rbFpv3Y86sQd/lKIuX/NkU/NgwJRHcPslclIm Xf0LmRBboko= =gZew -----END PGP SIGNATURE-----