MS12-074  Vulnerabilities in .NET Framework Could Allow Remote Code Execution

2012-11-13 This security update resolves four privately reported vulnerabilities in the Microsoft .NET Framework. The most severe of these vulnerabilities could allow remote code execution on a client system an attacker could convince a victim machine to use a malicious proxy auto configuration file and inject code into the currently running application. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. This security update is rated Critical for all supported editions of Microsoft .NET Framework except .NET Framework 1.0, Microsoft .NET Framework 1.1 and Microsoft .NET Framework 3.5 Service Pack 1. For more information, see the subsection, Affected and Non-Affected Software, in this section. The security update addresses the vulnerability by correcting the manner in which the .NET Framework retrieves the default web proxy configuration settings. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information. Recommendation. The majority of customers have automatic updating enabled and will not need to take any action because this security update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates and install this update manually. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871.For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update immediately using update management software, or by checking for updates using the Microsoft Update service. See also the section, Detection and Deployment Tools and Guidance, later in this bulletin. Known Issues. None
Vulnerabilities addressed in this bulletin:

Reflection Bypass Vulnerability

An elevation of privilege vulnerability exists in the way that .NET Framework validates the permissions of certain objects performing reflection. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
CVE-2012-1895

Code Access Security Info Disclosure Vulnerability

An information disclosure vulnerability exists in the Microsoft .NET Framework due to the improper sanitization of output when a function is called from partially trusted code. An attacker who successfully exploited this vulnerability could obtain confidential information contained on the target system.
CVE-2012-1896

.NET Framework Insecure Library Loading Vulnerability

CVE-2012-2519

Web Proxy Auto-Discovery Vulnerability

A remote code execution vulnerability exists in the way that the .Net Framework retrieves the default web proxy settings. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
CVE-2012-4776

WFP reflection optimization vulnerability

An elevation of privilege vulnerability exists in the way that the .Net Framework validates permissions for objects involved with reflection. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
CVE-2012-4777

Bulletin details at Microsoft.com