Microsoft Internet Explorer contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system. Updates are available.
Description
Microsoft Internet Explorer contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a vulnerable system.
The vulnerability is due to errors when Internet Explorer attempts to access deleted objects. An unauthenticated, remote attacker could exploit this vulnerability by persuading a user to visit a malicious website, allowing the attacker to execute code on the affected system.
Microsoft has confirmed this vulnerability in a security bulletin and has released updated software.
Warning Indicators
The following Microsoft products are affected:
Internet Explorer 9 for Windows Vista SP2 and prior
Internet Explorer 9 for Windows Vista x64 Edition SP2 and prior
Internet Explorer 9 for Windows Server 2008 for 32-bit Systems SP2 and prior
Internet Explorer 9 for Windows Server 2008 for x64-based Systems SP2 and prior
Internet Explorer 9 for Windows 7 for 32-bit Systems SP1 and prior
Internet Explorer 9 for Windows 7 for x64 based Systems SP1 and prior
Internet Explorer 9 for Windows Server 2008 R2 for x64-based Systems SP1 and prior
IntelliShield Analysis
To exploit the vulnerability, the attacker may provide a file or a link to a malicious website and use misleading language or instructions to persuade the user to open the file or follow the provided link.
Microsoft has corrected this vulnerability with an update that modifies the way Internet Explorer handles objects in memory.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the April 2012 security bulletin release. This Cisco bulletin, which assists administrators in identifying or mitigating these vulnerabilities using Cisco devices, is available at the following link: Cisco Applied Mitigation Bulletin: Microsoft Security Bulletin Release for April 2012.
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS12-023
Impact
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code on a targeted system. The code would execute in the context of the user who is logged in. If this user holds administrative privileges, a complete system compromise could occur.
Technical Information
The vulnerability is triggered when vulnerable versions of Internet Explorer attempt to access an object that has been deleted in a way that corrupts memory via the JScript9.dll file. An attacker could execute arbitrary code on the targeted system.
An unauthenticated, remote attacker who persuades a user to follow a link to a crafted website could exploit this vulnerability to execute arbitrary code on the system. The attacker may provide a link or embed an ActiveX control that is marked safe for initialization in an application or Office document that uses the Internet Explorer rendering engine. Successful exploitation could allow arbitrary code execution in the context of the user who is logged in. If the user holds administrative privileges, a complete system compromise could occur.
Safeguards
Administrators are advised to apply the appropriate updates.
Users should verify that unsolicited links are safe to follow.
Users are advised not to visit websites or follow links that have suspicious characteristics or cannot be verified as safe.
Administrators are advised to monitor affected systems.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Patches/Software
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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