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Attack Tree Analysis for dotnet/roslyn

Objective: Execute Arbitrary Code OR Leak Sensitive Information via Roslyn Exploitation

Attack Tree Visualization

Goal: Execute Arbitrary Code OR Leak Sensitive Information via Roslyn Exploitation
├── 1.  Abuse Roslyn's Compilation/Scripting Capabilities [HIGH RISK]
│   ├── 1.1  Inject Malicious Code into User-Provided Input [HIGH RISK]
│   │   ├── 1.1.1  Bypass Input Validation/Sanitization [CRITICAL]
│   │   │   ├── 1.1.1.1  Exploit Weaknesses in Custom Validation Logic
│   │   │   ├── 1.1.1.2  Find Edge Cases Not Covered by Validation
│   │   │   └── 1.1.1.3  Use Obfuscation Techniques to Evade Detection
│   │   ├── 1.1.2  Leverage Features Intended for Legitimate Use Maliciously [HIGH RISK]
│   │   │   ├── 1.1.2.1  Use `#r` (Reference) to Load Malicious Assemblies
│   │   │   ├── 1.1.2.2  Use `#load` to Load Malicious Scripts
│   │   │   ├── 1.1.2.3  Exploit Dynamic Compilation Features (e.g., `CSharpScript.EvaluateAsync`) [CRITICAL]
│   │   │   └── 1.1.2.4  Abuse Global Imports/Usings to Inject Dependencies
└── 3. Escalate Privileges After Initial Compromise (Post-Roslyn Exploitation) [CRITICAL]
    ├── 3.1 Leverage gained access from 1 or 2 to escalate privileges within the application or the hosting environment.
        ├── 3.1.1 Use obtained credentials.
        ├── 3.1.2 Exploit other vulnerabilities in the application.
        └── 3.1.3 Escalate to OS-level privileges.

Attack Tree Path: 1. Abuse Roslyn's Compilation/Scripting Capabilities [HIGH RISK]

  • Description: This is the primary attack vector. Roslyn is designed to compile and execute code, making it a target for attackers who want to run their own code on the system.
  • Mitigation Strategies:
    • Least Privilege: Run the Roslyn compilation/execution environment with the absolute minimum necessary privileges. Use a dedicated, low-privilege user account or a sandboxed environment (e.g., containers, AppDomains with restricted permissions).
    • Input Validation and Sanitization (see 1.1 below): This is the most critical mitigation for this entire branch.
    • API Restriction: Limit the set of .NET APIs and Roslyn features available to the compiled code. Use CSharpCompilationOptions and CSharpParseOptions to disable features like #r, #load, unsafe code, and access to specific assemblies or types.
    • Code Review: Thoroughly review any code that interacts with Roslyn APIs, especially code that handles user input.

Attack Tree Path: 1.1 Inject Malicious Code into User-Provided Input [HIGH RISK]

  • Description: This involves tricking the application into compiling and executing malicious code provided by the attacker. This is typically achieved by exploiting weaknesses in how the application handles user input.
    • Mitigation Strategies:
      • Strict Input Validation and Sanitization: Implement robust, whitelist-based input validation. Define a precise grammar for acceptable input and reject anything that doesn't conform. Avoid relying solely on blacklisting known malicious patterns.
      • Parameterized Queries/Commands: If the input is used to construct code, treat user-provided data as data, not as part of the code itself. This is analogous to using parameterized queries in SQL to prevent SQL injection. While Roslyn doesn't have direct parameterized queries, the principle is the same: separate code from data.
      • Contextual Encoding: If user input must be included in the generated code (e.g., for dynamic configuration), ensure it's properly encoded for the specific context (e.g., string escaping).
      • Regular Expression Hardening: If regular expressions are used for validation, ensure they are not vulnerable to ReDoS (Regular Expression Denial of Service) attacks.

Attack Tree Path: 1.1.1 Bypass Input Validation/Sanitization [CRITICAL]

  • Description: This is the crucial first step for many code injection attacks. If the attacker can bypass the application's input validation, they can inject arbitrary code. * Sub-Attack Vectors: * 1.1.1.1 Exploit Weaknesses in Custom Validation Logic: Attackers look for flaws in the application's custom validation rules (e.g., incorrect regular expressions, logical errors). * 1.1.1.2 Find Edge Cases Not Covered by Validation: Attackers try unusual or unexpected inputs that might not have been considered during development. * 1.1.1.3 Use Obfuscation Techniques to Evade Detection: Attackers use techniques like character encoding, comments, or whitespace manipulation to disguise malicious code and bypass validation. * Mitigation Strategies: (Reinforce the strategies from 1.1) * Thorough Testing: Test the input validation with a wide range of inputs, including boundary conditions, invalid characters, and known attack patterns. * Formal Verification (Advanced): In high-security scenarios, consider using formal methods to verify the correctness of the validation logic. * Multiple Layers of Validation: Implement validation at multiple layers of the application (e.g., client-side, server-side, and within the Roslyn compilation process).

Attack Tree Path: 1.1.2 Leverage Features Intended for Legitimate Use Maliciously [HIGH RISK]

  • Description: This involves using Roslyn's features in ways that were not intended by the application developers, leading to code execution. * Sub-Attack Vectors: * 1.1.2.1 Use #r (Reference) to Load Malicious Assemblies: If the application allows user-controlled #r directives, an attacker could load a malicious assembly. * 1.1.2.2 Use #load to Load Malicious Scripts: Similar to #r, if #load is allowed, an attacker could load a malicious script file. * 1.1.2.3 Exploit Dynamic Compilation Features (e.g., CSharpScript.EvaluateAsync) [CRITICAL]: Directly passing user input to these functions without proper sanitization is a major vulnerability. * 1.1.2.4 Abuse Global Imports/Usings to Inject Dependencies: Less common, but if the application allows modification of global imports, an attacker could inject malicious dependencies. * Mitigation Strategies: * Disable Unnecessary Features: Use CSharpCompilationOptions and CSharpParseOptions to disable features like #r and #load if they are not absolutely required. * Whitelist Allowed Assemblies/Scripts: If #r or #load are necessary, maintain a strict whitelist of allowed assemblies and scripts. * Sandboxing (see 1. above): Run the compilation in a restricted environment to limit the impact of any malicious code. * Careful API Usage: Avoid directly passing user input to CSharpScript.EvaluateAsync or similar functions. Instead, use a carefully controlled template or a domain-specific language (DSL) that limits the expressiveness of user input.

Attack Tree Path: 3. Escalate Privileges After Initial Compromise (Post-Roslyn Exploitation) [CRITICAL]

  • Description: Even if the initial Roslyn exploit is limited (e.g., only allows reading certain files), the attacker will likely try to escalate their privileges to gain broader control over the system.
    • Sub-Attack Vectors:
      • 3.1.1 Use obtained credentials. If the attacker can obtain credentials (e.g., by reading configuration files), they can use them to access other parts of the system.
      • 3.1.2 Exploit other vulnerabilities in the application. The attacker might use the initial Roslyn exploit to find and exploit other vulnerabilities in the application.
      • 3.1.3 Escalate to OS-level privileges. The ultimate goal is often to gain full control of the operating system.
    • Mitigation Strategies:
      • Principle of Least Privilege (Application-Wide): Ensure that all parts of the application run with the minimum necessary privileges. This limits the damage an attacker can do even after a successful exploit.
      • Defense in Depth: Implement multiple layers of security throughout the application and the hosting environment.
      • Regular Security Audits and Penetration Testing: Regularly assess the security of the entire application, not just the Roslyn-specific components.
      • Intrusion Detection and Response: Implement systems to detect and respond to suspicious activity.
      • Secure Configuration: Ensure that the operating system and all software components are securely configured.
      • Patching: Keep the operating system and all software components up-to-date with the latest security patches.