Advisories
Windows Embedded Open Type (EOT) Font Heap Overflow Vulnerability
Release Date:
January 10, 2006
Date Reported:
July 31, 2005
Patch Development Time (In Days):
Severity:
High (Remote Code Execution)
Vendor:
Microsoft
Systems Affected:
Windows ME
Windows 98
Windows NT
Windows 2000
Windows XP SP1 / SP2
Windows Server 2003 SP0 / SP1
Overview:
eEye Digital Security has discovered a vulnerability in the way Windows uncompresses Embedded Open Type fonts that would allow the author of a malicious web page to execute arbitrary code on the system of a user who visits the site, at the privilege level of that user.
Embedded Open Type fonts are referenced through the use of style data, as the following snippet illustrates:
@font-face {
font-family: Abysmal;
font-style: normal;
font-weight: normal;
src: url(evil.eot);
Although these fonts typically have .eot file extensions, it should be noted that any extension may be used in order to exploit this vulnerability.
Technical Details:
A heap overflow vulnerability exists in T2EMBED.DLL, which Internet Explorer invokes to process EOT fonts. The data within an EOT file is compressed in Agfa MicroType Express format, which hosts an LZ-compressed stream that includes a 24-bit allocation size. This size + 1C00h is allocated within the function MTX_LZCOMP_UnPackMemory, but the resulting allocation size is not validated before data is copied into the block, allowing a malformed EOT file to cause an essentially arbitrary-length heap buffer overflow with binary data.
Protection:
Retina Network Security Scanner has been updated to identify this vulnerability.
Blink - Endpoint Vulnerability Prevention - preemptively protects from this vulnerability.
Vendor Status:
Microsoft has released a patch for this vulnerability. The patch is available at:
http://www.microsoft.com/technet/security/bulletin/ms06-002.mspx
Credit:
Discovery: Fang Xing
Related Links:
Retina Network Security Scanner - Free Trial
Blink Endpoint Vulnerability Prevention - Free Trial
Greetings:
eEye Research and Derek for all his help.
Copyright (c) 1998-2009 eEye Digital Security
Permission is hereby granted for the redistribution of this alert electronically. It is not to be edited in any way without express consent of eEye. If you wish to reprint the whole or any part of this alert in any other medium excluding electronic medium, please email alert@eEye.com for permission.
Disclaimer
The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are no warranties, implied or express, with regard to this information. In no event shall the author be liable for any direct or indirect damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk.
January 10, 2006
Date Reported:
July 31, 2005
Patch Development Time (In Days):
 |
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|
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| 163 |
Severity:
High (Remote Code Execution)
Vendor:
Microsoft
Systems Affected:
Windows ME
Windows 98
Windows NT
Windows 2000
Windows XP SP1 / SP2
Windows Server 2003 SP0 / SP1
Overview:
eEye Digital Security has discovered a vulnerability in the way Windows uncompresses Embedded Open Type fonts that would allow the author of a malicious web page to execute arbitrary code on the system of a user who visits the site, at the privilege level of that user.
Embedded Open Type fonts are referenced through the use of style data, as the following snippet illustrates:
@font-face {
font-family: Abysmal;
font-style: normal;
font-weight: normal;
src: url(evil.eot);
Although these fonts typically have .eot file extensions, it should be noted that any extension may be used in order to exploit this vulnerability.
Technical Details:
A heap overflow vulnerability exists in T2EMBED.DLL, which Internet Explorer invokes to process EOT fonts. The data within an EOT file is compressed in Agfa MicroType Express format, which hosts an LZ-compressed stream that includes a 24-bit allocation size. This size + 1C00h is allocated within the function MTX_LZCOMP_UnPackMemory, but the resulting allocation size is not validated before data is copied into the block, allowing a malformed EOT file to cause an essentially arbitrary-length heap buffer overflow with binary data.
Protection:
Retina Network Security Scanner has been updated to identify this vulnerability.
Blink - Endpoint Vulnerability Prevention - preemptively protects from this vulnerability.
Vendor Status:
Microsoft has released a patch for this vulnerability. The patch is available at:
http://www.microsoft.com/technet/security/bulletin/ms06-002.mspx
Credit:
Discovery: Fang Xing
Related Links:
Retina Network Security Scanner - Free Trial
Blink Endpoint Vulnerability Prevention - Free Trial
Greetings:
eEye Research and Derek for all his help.
Copyright (c) 1998-2009 eEye Digital Security
Permission is hereby granted for the redistribution of this alert electronically. It is not to be edited in any way without express consent of eEye. If you wish to reprint the whole or any part of this alert in any other medium excluding electronic medium, please email alert@eEye.com for permission.
Disclaimer
The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are no warranties, implied or express, with regard to this information. In no event shall the author be liable for any direct or indirect damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk.
