Published:
22 April 2001
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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2001.159 -- Microsoft Security Bulletin MS01-015 (version 2.0) IE can Divulge Location of Cached Content 23 April 2001 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Microsoft Internet Explorer 5.01 Microsoft Internet Explorer 5.5 Microsoft Windows Scripting Host 5.1 Microsoft Windows Scripting Host 5.5 Vendor: Microsoft Impact: Execute Arbitrary Code/Commands Access Required: Remote Ref: ESB-2001.103 ESB-2000.386 ESB-2000.204 ESB-2000.101 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- - - ---------------------------------------------------------------------- Title: IE can Divulge Location of Cached Content Released: 06 March 2001 Revised: 20 April 2001 (version 2.0) Software: Microsoft Windows Script Host 5.1 and 5.5 Impact: Run code of attacker's choice Bulletin: MS01-015 Microsoft encourages customers to review the Security Bulletin at: http://www.microsoft.com/technet/security/bulletin/MS01-015.asp. - - ---------------------------------------------------------------------- Reason for Revision: ==================== A regression was found in the previously released Windows Script Host patch referenced in the first version of this security bulletin. We have updated and re-released the Windows Script Host patch and have updated the bulletin accordingly. The re-release only applies to changes with the Windows Script Host patches available in the bulletin. No changes have been made to the originally released Internet Explorer patches. Customers who applied the Windows Script Host patch when this bulletin was first released should download and apply the updated Windows Script Host patch referenced in the bulletin. Customers who did not apply the Windows Script Host when this bulletin was first released are encouraged to apply the Windows Script Host patch listed in the bulletin. Issue: ====== The IE security architecture provides a caching mechanism that is used to store content that needs to be downloaded and processed on the user's local machine. The purpose of the cache is to obfuscate the physical location of the cached content, in order to ensure that the web page or HTML e-mail will work through the IE security architecture to access the information. This ensures that the uses of the information can be properly restricted. A vulnerability exists because it is possible for a web page or HTML e- mail to learn the physical location of cached content. Armed with this information, an attacker could cause the cached content to be opened in the Local Computer Zone. This would enable him to launch compiled HTML help (.CHM) files that contain shortcuts to executables, thereby enabling him to run the executables. In addition to eliminating this vulnerability, the patches provided below eliminate three other vulnerabilities that either pose significantly less risk or could only be exploited in very restricted situations: A variant of the Frame Domain Verification vulnerability discussed in Microsoft Security Bulletins MS00-033, MS00-055, and MS00-093. The vulnerability could enable a malicious web site operator to open two browser windows, one in the web site's domain and the other on the user's local file system, and to pass information from the latter to the former. This could enable the web site operator to read, but not change, any file on the user's local computer that could be opened in a browser window. A vulnerability that is identical in effect to the Frame Domain Verification vulnerability, but which actually results from a flaw in Windows Script Host rather than IE. Because it could only be exploited via IE, we have provided the fix here. The fix that was released on March 06, 2001, was subsequently discovered to have a regression error, and a corrected version was released on April 19, 2001. A vulnerability that affects how Telnet sessions are invoked via IE. By design, telnet sessions can be launched via IE. However, a vulnerability exists because when doing so, IE will start Telnet using any command-line options the web site specifies. This only becomes a concern when using the version of the Telnet client that installs as part of Services for Unix (SFU) 2.0 on Windows NT 4.0 or Windows 2000 machines. The version of the Telnet client in SFU 2.0 provides an option for creating a verbatim transcript of a Telnet session. An attacker could start a session using the logging option, then stream an executable file onto the user's system in a location that would cause it to be executed automatically the next time the user booted the machine. The flaw does not lie in the Telnet client, but in IE, which should not allow Telnet to be started remotely with command-line arguments. Mitigating Factors: ==================== None of the vulnerabilities could be exploited without some user action - either browsing to the attacker's site or opening a mail from him. - Customers who exercise safe browsing habits would be less likely visit untrustworthy sites, and customers who have used the Security Zones feature to restrict what HTML mail can do would be less likely to be affected by this vulnerability. - The variants of the "frame domain verification" vulnerability discussed above could only be used to view files, and only file types that can be opened in a browser window. - The vulnerability affecting Telnet invocation is only a concern for customers who are using the Telnet client that ships as part of Services for Unix 2.0. Other versions of Telnet do not include the command-line feature to create log files. Patch Availability: =================== - A patch is available to fix this vulnerability. Please read the Security Bulletin http://www.microsoft.com/technet/security/bulletin/ms01-015.asp for information on obtaining this patch. Acknowledgment: =============== - Oliver Friedrichs of securityfocus.com (for reporting the Telnet invocation issue) - - --------------------------------------------------------------------- THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. - -----BEGIN PGP SIGNATURE----- Version: PGP Personal Privacy 6.5.3 iQEVAwUBOuDW8o0ZSRQxA/UrAQF4Wgf/ZD7WgzNHbS9chijhW8TU/JilgMh0Eybo 0uJVD06vixpQNgd2w0AIMbgsGYwbteAj7d+/OS9xO9X78avr+ZaiBfuMuzQwse/t FZQp7kxbOjfhia0636kqbHhuGlH/EiMGbL4Jql9njO10unxIq73QGB5Ljmx8DF+k q8VLZ/FrUanY1zF8GaH/I6wx7ileL5d1oxsyPkKw2DsIf7ZQjFe/Q3puIKyIDGyX 854umfUxThAoQH2zOQ/8hOg/jxC1e5SRmQ7Wjv4KyQeX4LpCROiDd1GO9h1xixSe 5K7dj9MdDr1nDis70+q+r1KRylf766q0j/LTt0zea0BEbbVSp7BjLQ== =owqt - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- 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. 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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 iQCVAwUBOuQNEih9+71yA2DNAQGfFQP6A152qvdVJIlJnZ3fAgoQ8LESjzQZB5Yi Wp6pW8K/h1HQEMlWSQ6ewnlOxkV+aTd8o2/FGFvDLyDNDJJ2PQw4WD3iKWKQUepS +Gx/h48zZI6nXTLVb/Pdt3GHGB/xopd7m/MkMI5fjGl0OOjSqgz4/tnXw/MGYDsx 9YVcMym0mPM= =+GxL -----END PGP SIGNATURE-----