Microsoft Internet Explorer contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.
The vulnerability exists due to the improper processing of malformed web pages. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious web page. If successful, the attacker could execute arbitrary code 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 6.0 SP2 and prior, 7.0, and 8.0 are vulnerable when running on the following 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 Vista SP1 and 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
Windows 7 for x64-based Systems
Windows Server 2008 R2 for x64-based Systems
Windows Server 2008 R2 for Itanium-based Systems
The vulnerability is due to improper memory operations performed by the CAttrArray::PrivateFind() function in the mshtml.dll library of the affected software.
An unauthenticated, remote attacker could exploit the vulnerability by convincing a user to open a website containing a malicious style sheet property. The processing of the property could cause the vulnerable library to unexpectedly free a memory object. Later access of the memory object could trigger memory corruption. The attacker could exploit the memory corruption to execute arbitrary code with the privileges of the user.
To exploit this vulnerability, an attacker must convince a user to view a malicious web page. The attacker may provide links to malicious web pages within e-mail or instant messages. When viewed, the web page could trigger the execution of arbitrary code on the system. Depending on the privileges of the user, the attacker could take complete control over the system.
Administrators are advised to apply the available software 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 are advised to monitor critical systems.
Microsoft has released a security bulletin at the following link: MS10-071
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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