This document discusses .NET Framework 4 security architecture, including application domains, code verification processes, code access security (CAS), role-based security concepts like authentication and authorization, and cryptography. It also covers security transparency attributes, demonstrates a MS13-015 vulnerability exploit, and provides contact information for the author.

1. Know Your Security Model
Mikhail Shcherbakov
9-я конференция .NET разработчиков
12 октября 2014
dotnetconf.ru

2. 2
About me
• Senior software developer at Positive
Technologies
• Working on Application Inspector - source
code analyzer
• Previous team lead at Acronis and Luxoft

3. 3
Terms
C# 5.0 Language Specification
Common Language Infrastructure (CLI) Standard ECMA-335

4. 4
.NET Framework 4 Security
Architecture
• Application Domains
• The verification process
• Code Access Security (CAS)
o Policy
o Permissions
o Enforcement
• Role-based security
o Authentication
o Authorization
o Principal and Identity
• Cryptography

5. 5
.NET Framework 4 Security
Architecture
• Application Domains
• The verification process
• Code Access Security (CAS)
o Policy
o Permissions
o Enforcement
• Role-based security
o Authentication
o Authorization
o Principal and Identity
• Cryptography

6. 6
Knowledge in Practice
• CAS is the base of security
• Development of extensible and security-
sensitive applications
• Troubleshooting and knowledge about the
internals
o ASP.NET / IIS o Silverlight
o SQL CLR o XBAP
o ClickOnce o Sharepoint

7. 7
Application Domains
• Fully Trusted and Partially Trusted
• Heterogeneous and Homogeneous
• Sandboxing by AppDomain

8. 8
Type Safety
• C# compilation
• Just-in-time (JIT) compilation
• Native Image Generator (Ngen.exe)
• PEVerify tool

9. 9
Code Access Security
• Policy (deprecated in .NET Framework 4)
• Permissions
• Enforcement
o Fully Trusted assemblies in Partially Trusted AppDomain
o Security Transparency Code
o Assert permissions
o SecurityPermission o RegistryPermission
o ReflectionPermission o SocketPermission
o FileIOPermission o WebPermission

10. 10
Level 2 Security Transparency
Critical
Full Trust code that can do anything
Safe Critical
Full Trust code Provides access to Critical code
Transparent
Only verifiable code Cannot p/invoke Cannot elevate/assert

11. 11
Security Transparency Attributes
Assembly
Level
Type
Level
Member
Level
SecurityTransparent   
SecuritySafeCritical   
SecurityCritical   
AllowPartiallyTrustedCallers   
SecAnnotate.exe - .NET Security Annotator Tool

12. 12
Demo MS13-015 vulnerability
Could Allow Elevation of Privilege (KB2800277)
Exploited by Trusted Chain attack

13. 13
Thank you for your attention!
Mikhail Shcherbakov
Positive Technologies
linkedin.com/in/mikhailshcherbakov
yuske.dev@gmail.com
github.com/yuske