December 8, 2015
Microsoft Silverlight is prone to a remote code-execution vulnerability. An attacker can exploit this issue to execute arbitrary code with the privileges of the currently logged-in user. Failed exploit attempts will likely result in a denial-of-service condition.
- Microsoft Silverlight 5 Developer Runtime
- Microsoft Silverlight 5.0
Block external access at the network boundary, unless external parties require service.
If global access isn’t needed, filter access to the affected computer at the network boundary. Restricting access to only trusted computers and networks might greatly reduce the likelihood of successful exploits.
Run all software as a nonprivileged user with minimal access rights.
To reduce the impact of latent vulnerabilities, always run nonadministrative software as an unprivileged user with minimal access rights.
Do not follow links provided by unknown or untrusted sources.
Attackers could exploit this vulnerability by enticing a user to visit a malicious website. Do not follow links provided by sources of questionable integrity.
Set web browser security to disable the execution of script code or active content.
Disable support for script code and active content within a client browser to reduce the chances of a successful exploit. Note that this mitigation tactic might adversely affect legitimate websites that rely on the execution of browser-based script code.
Implement multiple redundant layers of security.
Since this issue may be leveraged to execute code, we recommend memory-protection schemes, such as nonexecutable stack/heap configurations and randomly mapped memory segments. This tactic may complicate exploits of memory-corruption vulnerabilities.
Updates are available. Please see the references or vendor advisory for more information.
© 1995- Symantec Corporation
Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Security Response. Reprinting the whole or part of this alert in any medium other than electronically requires permission from firstname.lastname@example.org.
The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.
Symantec, Symantec products, Symantec Security Response, and email@example.com are registered trademarks of Symantec Corp. and/or affiliated companies in the United States and other countries. All other registered and unregistered trademarks represented in this document are the sole property of their respective companies/owners.