Effective 2019 Sep 15, Cisco will no longer publish non-Cisco product alerts. Cisco will continue to publish Security Advisories to address third-party software vulnerabilities per the Cisco Security Vulnerability Policy.
Multivendor Vulnerability Alert
Microsoft Internet Explorer HTTP Redirect Memory Corruption Vulnerability
Microsoft Internet Explorer contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.
The vulnerability exists because Internet Explorer fails to properly process previously removed or uninitialized memory objects when it performs HTTP redirections. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious website. If successful, the attacker could execute arbitrary code on the system with the privileges of the user.
Microsoft has confirmed the vulnerability in a security bulletin and released software updates.
Indicators of Compromise
Microsoft Internet Explorer versions 7, 8, and 9 are vulnerable when they are running on the following Microsoft systems:
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 Server 2003 for Itanium-based Systems 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 Server 2008 for Itanium-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 exists due to an incorrect handling of HTTP 302 Redirect responses for the Conversation Definition Language (CDL) protocol by the affected software. Due to this flaw, a reference counter for a certain object could be incorrectly calculated, leading to memory corruption.
An unauthenticated, remote attacker could exploit this vulnerability by persuading a targeted user to view a malicious web page that is designed to issue crafted HTTP 302 Redirect responses. Processing such responses could trigger a use-after-free error, leading to memory corruption. The attacker could leverage this memory corruption to execute arbitrary code on the targeted system.
To exploit this 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.
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 critical systems.
Microsoft has released a security bulletin at the following link: MS11-050
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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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.