===============================ADVISORY===============================
Systems Affected:    .NET 1.0 through .NET 4
Severity:            High
Category:            Remote Code Execution
Author:              Context Information Security
Reported to vendor:  17th March 2011
Advisory Issued:     8th May 2012
Reference:           CVE-2012-0160, CVE-2012-0161 
===============================ADVISORY===============================
 
Description
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The Microsoft .NET framework (in all released versions) is vulnerable to a number of attacks through the misuse of binary serialization which could be leveraged to disclose important information or to achieve remote code execution. 
 
Analysis
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The .NET framework has a number of serialization mechanisms a developer can use to load and save object instances either to permanent storage locations or for use in the transport of objects across boundaries. Probably the most important of these is the IFormatter serializers, specifically BinaryFormatter which has existed in one form since the very first version of the framework. 
 
It is common to see this used as a mechanism for data storage, object marshalling and object cloning. This can lead to situations where an attacker can introduce malicious objects into an application either remotely over a network or through a sandboxed environment.
 
Through the use of specific functionality an attacker can then leverage this situation to circumvent security mechanisms and gain remote code execution without user interaction or to disclosure important information.
 
 
Technologies Affected
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Microsoft .Net Frameworks 1.0 through 4.0
 
Vendor Response
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Microsoft advises users to patch the .Net Framework to the latest version.  See the following Microsoft security bulletin for more details:
http://technet.microsoft.com/en-us/security/bulletin/ms12-035
 
There are a number of mitigations which reduce the severity of the issues which are also detailed in Microsoft’s bulletin. 
 
Disclosure Timeline
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13th March 2011 – Vendor Notification
8th May 2012 – Vendor Patch Released
 
 
Credits
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James Forshaw of Context Information Security
 
 
About Context Information Security
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 Context was launched in 1998 and has a client base that includes some of the world’s most high profile blue chip companies, alongside government organisations. An exceptional level of technical expertise underpins all Context services, while a detailed and comprehensive approach helps clients to attain a deeper understanding of security vulnerabilities, threats or incidents. The company’s strong track record is based above all, on the technical skills, professionalism, independence and integrity of its consultants.   
 
Many of the world's most successful organisations turn to Context for technical assurance, incident response and investigation services. Context is also at the forefront of research and development in security technology.  As well as publishing white papers and blogs addressing current and emerging security threats and trends, Context consultants are frequently invited to present at open and closed industry events around the world. Context delivers a comprehensive portfolio of advanced technical services and with offices in the UK, Germany and Australia, is ideally placed to work with clients worldwide.  
 
Web:        www.contextis.com
Email:      disclosure@contextis.com