Microsoft Internet Explorer contains a vulnerability that could allow an unauthenticated, remote attacker to access sensitive browser-based information.
The vulnerability is due to improper handling of specially crafted Content-Disposition HTTP headers. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious website. If successful, the attacker could access sensitive browser-based information.
Microsoft confirmed the vulnerability in a security bulletin and released software updates.
Indicators of Compromise
Microsoft Internet Explorer 6, 7, 8, and 9 are vulnerable when running on the following platforms:
Windows XP SP3 and prior
Windows XP Professional x64 Edition SP2 and prior
Windows Server 2003 SP2 and prior
Windows Server 2003 x64 Edition SP2 and prior
Windows Vista SP2 and prior
Windows Vista x64 Edition SP2 and prior
Windows Server 2008 for 32-bit Systems SP2 and prior
Windows Server 2008 for x64-based Systems SP2 and prior
Windows 7 for 32-bit Systems SP1 and prior
Windows 7 for x64-based Systems SP1 and prior
Windows Server 2008 R2 for x64-based Systems SP1 and prior
Windows Server 2008 R2 for Itanium-based Systems SP1 and prior
The vulnerability is due to improper handling of specially crafted Content-Disposition HTTP headers.
An unauthenticated, remote attacker could exploit the vulnerability by convincing a user to view a website that is designed to return requests with malicious Content-Disposition HTTP headers. The processing of the headers could cause the incorrect rendering of the website, which could return sensitive browser-based information to the user.
To exploit the vulnerability, the attacker may provide a link that directs a user to a malicious site and use misleading language or instructions to persuade the user to follow the provided link.
Administrators are advised to apply the appropriate updates.
Users are advised not to open e-mail messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in e-mail messages are safe, they are advised not to open them.
Users are advised to read e-mail messages in plain text.
Administrators may consider configuring Internet Explorer to prompt users before running Active Scripting or ActiveX controls by setting the Internet and Local Intranet security zone settings to High. Alternately, administrators could disable Active Scripting and ActiveX controls in these security zones.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Administrators are advised to monitor affected systems.
Microsoft has released a security bulletin at the following link: MS11-099
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
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