Microsoft Silverlight contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.
The vulnerability is due to improper memory operations performed by the affected software. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a web page that contains a crafted Microsoft Silverlight application. When the malicious application is processed, the attacker could access memory in an unsafe manner, which could be used to execute arbitrary code with the privileges of the user.
Functional code that exploits this vulnerability is publicly available.
Microsoft has confirmed the vulnerability in a security bulletin and released software updates.
Indicators of Compromise
Microsoft Silverlight version 5 is vulnerable when installed on the following systems:
All supported releases of Microsoft Windows clients
All supported releases of Microsoft Windows servers
Apple Mac OS X
The vulnerability is due to insufficient boundary restrictions imposed on user-supplied input by the affected software.
An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a web page with Silverlight that could submit a crafted count parameter value to the BitmapSource.ReadStream(). If the count value of the array item is larger than the array.Length value, the software may write attacker-controlled data outside the array, which could be used as input by the native BitmapSource_SetSource() from agcore.dll. This could allow the attacker to process malicious data and execute arbitrary code on the system with the privileges of 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.
Microsoft has corrected this vulnerability by modifying the way Microsoft Silverlight checks memory pointers when rendering HTML objects.
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 disabling the Silverlight ActiveX control from running in Internet Explorer, Mozilla Firefox and Google Chrome.
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: MS13-022
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 Microsoft Update service. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
Additional technical information to describe the Microsoft Silverlight memory dereference arbitrary code execution vulnerability is available. Functional code that demonstrates an exploit of this vulnerability is also publicly available.
2013-October-23 13:21 GMT
Microsoft Silverlight contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system. Updates are available.
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