Skip to content

Latest commit

 

History

History
149 lines (123 loc) · 15.9 KB

sec-design-deep-analysis.md

File metadata and controls

149 lines (123 loc) · 15.9 KB

Okay, let's perform a deep security analysis of JSPatch based on the provided design document.

1. Objective, Scope, and Methodology

  • Objective: To conduct a thorough security analysis of the JSPatch framework and its integration into an iOS application, focusing on identifying potential vulnerabilities, assessing their impact, and recommending mitigation strategies. The analysis will cover key components like patch delivery, integrity verification, JavaScript execution, and interaction with Objective-C.
  • Scope:
    • The JSPatch library itself (as available on GitHub: https://github.com/bang590/jspatch).
    • The integration of JSPatch into a hypothetical iOS application, as described in the design document.
    • The patch delivery mechanism (assuming a custom server using HTTPS).
    • The interaction between JavaScript code (patches) and Objective-C code.
    • The security controls mentioned in the design document, both existing and recommended.
    • The build and deployment processes as described.
  • Methodology:
    1. Code Review (Static Analysis): Examine the JSPatch source code on GitHub to understand its internal workings, identify potential vulnerabilities, and assess the implementation of security controls.
    2. Architecture Review: Analyze the provided C4 diagrams and deployment diagrams to understand the system's architecture, data flow, and trust boundaries.
    3. Threat Modeling: Based on the design document, identify potential threats and attack vectors, considering the business risks and security posture.
    4. Vulnerability Analysis: Identify specific vulnerabilities based on the code review, architecture review, and threat modeling.
    5. Mitigation Recommendations: Propose actionable and specific mitigation strategies to address the identified vulnerabilities.
    6. Documentation Review: Analyze provided documentation.

2. Security Implications of Key Components

Let's break down the security implications of the key components identified in the design review:

  • JSPatch Library (Core Logic):

    • Implication: This is the heart of the system and the most critical component. It handles parsing, interpreting, and applying JavaScript patches to Objective-C code. Any vulnerability here can be exploited to execute arbitrary code. The library's interaction with JavaScriptCore is a key area of concern. The way it bridges Objective-C and JavaScript (method swizzling, argument conversion, etc.) is crucial for security.
    • Specific Concerns:
      • Injection Vulnerabilities: Flaws in how the library handles input from the JavaScript patch file could allow for code injection. This includes how strings, numbers, and other data types are converted between JavaScript and Objective-C.
      • Logic Errors: Bugs in the patching logic could lead to incorrect application behavior or crashes, potentially creating denial-of-service vulnerabilities.
      • API Exposure: The specific set of Objective-C APIs exposed to JavaScript is critical. Overly permissive access could allow malicious patches to perform unauthorized actions.
      • Reflection and Method Swizzling: JSPatch heavily relies on Objective-C runtime features like reflection and method swizzling. Incorrect use of these features can lead to instability and vulnerabilities.
      • Error Handling: How the library handles errors during patch application is important. Poor error handling could lead to unexpected states or expose sensitive information.

  • JavaScriptCore Framework:

    • Implication: JSPatch relies on Apple's JavaScriptCore for JavaScript execution. While generally secure, JavaScriptCore itself can have vulnerabilities. JSPatch inherits any risks associated with this framework.
    • Specific Concerns:
      • Exploits in JavaScriptCore: Zero-day vulnerabilities or unpatched known vulnerabilities in JavaScriptCore could be exploited through JSPatch.
      • Memory Corruption: Bugs in JavaScriptCore could lead to memory corruption vulnerabilities, potentially allowing for arbitrary code execution.
      • Side-Channel Attacks: While less likely, sophisticated attacks might exploit side-channel vulnerabilities in JavaScriptCore to leak information.

  • Networking Module (Patch Delivery):

    • Implication: This component is responsible for downloading patches from the server. The security of this process is paramount to prevent Man-in-the-Middle (MitM) attacks and ensure patch integrity.
    • Specific Concerns:
      • Man-in-the-Middle (MitM) Attacks: If HTTPS is not properly implemented (e.g., weak ciphers, no certificate validation), an attacker could intercept and modify patches in transit.
      • Insecure Connections: Using plain HTTP or improperly configured HTTPS would expose the patch data to eavesdropping and tampering.
      • Denial-of-Service (DoS): The patch server could be targeted by DoS attacks, preventing the application from receiving updates.
      • Improper Certificate Pinning Implementation: If certificate pinning is used, but implemented incorrectly, it could be bypassed.

  • Local Storage:

    • Implication: If patches are stored locally, the security of that storage is important. While iOS provides data protection mechanisms, they need to be used correctly.
    • Specific Concerns:
      • Unauthorized Access: If patches are stored in an insecure location, other apps or a jailbroken device might be able to access or modify them.
      • Data Protection Classes: Using the appropriate iOS Data Protection classes (e.g., NSFileProtectionComplete) is crucial to ensure that patches are encrypted at rest.
      • Tampering: If an attacker can modify the stored patch files, they can inject malicious code.

  • Original App Code:

    • Implication: Even with JSPatch, the security of the original Objective-C code is still important. Vulnerabilities in the original code can be exploited even without using JSPatch.
    • Specific Concerns:
      • Standard iOS Vulnerabilities: The original code could contain typical iOS vulnerabilities like buffer overflows, format string bugs, SQL injection (if using a local database), etc.
      • Interaction with Patched Code: Vulnerabilities in the original code could be triggered or exacerbated by patched code.

  • Patch Server:

    • Implication: The security of the server hosting the patches is critical. A compromised server could be used to distribute malicious patches to all users.
    • Specific Concerns:
      • Server-Side Vulnerabilities: The server could be vulnerable to standard web application attacks (e.g., SQL injection, cross-site scripting, remote code execution).
      • Unauthorized Access: Weak authentication or authorization mechanisms could allow attackers to upload malicious patches.
      • Compromised Credentials: If the developer's credentials for accessing the server are compromised, an attacker could gain control.

3. Architecture, Components, and Data Flow (Inferred)

Based on the codebase and documentation, we can infer the following:

  • Architecture: Client-Server. The iOS app (client) downloads JavaScript patches from a developer-controlled server.
  • Components:
    • JSPatch Client: Embedded within the iOS app. Handles downloading, parsing, and applying patches.
    • JSPatch Server: Hosts the JavaScript patch files.
    • JavaScriptCore: Apple's JavaScript engine, used by the JSPatch client.
  • Data Flow:
    1. Developer creates a JavaScript patch file.
    2. Developer signs the patch file (using a private key).
    3. Developer uploads the signed patch file to the Patch Server.
    4. The JSPatch-enabled app (on the user's device) periodically checks for new patches.
    5. The app downloads the patch file from the Patch Server (over HTTPS).
    6. The app verifies the signature of the patch file (using the developer's public key).
    7. If the signature is valid, the JSPatch library parses the JavaScript code.
    8. The JSPatch library uses JavaScriptCore to execute the JavaScript code.
    9. The JavaScript code interacts with the Objective-C code through the bridge provided by JSPatch (using method swizzling and reflection).
    10. The patched code modifies the application's behavior.

4. Specific Security Considerations (Tailored to JSPatch)

  • Arbitrary Code Execution: This is the most significant risk. A compromised patch or a vulnerability in the JSPatch library could allow an attacker to execute arbitrary code on the user's device.
  • Data Exfiltration: Malicious patches could access and exfiltrate sensitive user data.
  • Privilege Escalation: While iOS sandboxing limits the damage, a sophisticated attacker might be able to combine a JSPatch vulnerability with other exploits to gain higher privileges.
  • Denial of Service: Malicious or poorly written patches could crash the application or make it unusable.
  • App Store Rejection: Apple could reject the app if they detect that JSPatch is being used to circumvent their review process or violate their guidelines.
  • Supply Chain Attack: A vulnerability in the JSPatch library itself (on GitHub) could be exploited in all apps that use it.
  • Reputation Damage: A successful attack exploiting JSPatch could severely damage the app's reputation and user trust.

5. Actionable Mitigation Strategies (Tailored to JSPatch)

These strategies are prioritized based on their impact on mitigating the most critical risks:

  1. Secure Patch Delivery and Integrity (Highest Priority):

    • HTTPS with Certificate Pinning: Use HTTPS for all communication with the patch server. Implement certificate pinning to prevent MitM attacks. Use a strong, modern TLS configuration. This is absolutely critical.
    • Digital Signatures: Digitally sign all patch files using a strong cryptographic algorithm (e.g., ECDSA with SHA-256). The private key must be stored securely (ideally in a hardware security module or a secure enclave). The app should verify the signature before applying the patch.
    • Patch Origin Verification: Embed the public key used for signature verification within the app itself (do not download it from the server). This prevents an attacker from substituting a different public key.
    • Regular Key Rotation: Rotate the signing keys periodically to limit the impact of a key compromise.
    • Version Control for Patches: Implement a versioning system for patches to allow for rollback to previous versions if a patch introduces issues.

  2. Input Validation and Sanitization (High Priority):

    • Strict Type Checking: Thoroughly validate all data passed between JavaScript and Objective-C. Ensure that types are as expected and that values are within acceptable ranges.
    • Whitelist Allowed APIs: Maintain a strict whitelist of Objective-C APIs that are exposed to JavaScript. Do not expose any APIs that are not absolutely necessary. Review this whitelist regularly.
    • Context-Aware Input Validation: Validate input based on the context in which it will be used. For example, if a string is expected to be a URL, validate it as a URL.
    • Escape/Encode Output: Properly escape or encode any data from JavaScript that is used in Objective-C contexts (e.g., when displaying data in the UI or interacting with the file system).

  3. Sandboxed JavaScript Execution (High Priority):

    • Review JavaScriptCore Security: Stay informed about any security updates or vulnerabilities related to JavaScriptCore. Apply updates promptly.
    • Consider Web Workers (If Feasible): Explore the possibility of running the JavaScript code within a Web Worker context. This provides an additional layer of isolation, although it might have limitations in terms of accessing Objective-C APIs. This needs careful research as it might not be directly compatible with JSPatch's current architecture.
    • Resource Limits: If possible, set resource limits (e.g., memory, CPU) on the JavaScript execution environment to prevent denial-of-service attacks.

  4. Runtime Monitoring and Anomaly Detection (Medium Priority):

    • Monitor API Calls: Implement runtime monitoring to detect suspicious API calls made by the patched code. This could involve logging API calls and comparing them against a baseline of expected behavior.
    • Data Access Patterns: Monitor data access patterns to detect unusual or unauthorized access to sensitive data.
    • Crash Reporting: Implement robust crash reporting to identify and diagnose issues caused by patches. Ensure that crash reports do not contain sensitive information.
    • Alerting: Set up alerts for any detected anomalies or suspicious behavior.

  5. Secure Development Practices (Medium Priority):

    • Code Reviews: Conduct thorough code reviews of both the original Objective-C code and the JavaScript patches. Focus on security vulnerabilities.
    • SAST and DAST: Use Static Application Security Testing (SAST) tools to scan the Objective-C code for vulnerabilities. Consider using Dynamic Application Security Testing (DAST) tools to test the running application, including the patching mechanism.
    • Secure Coding Training: Provide secure coding training to developers, covering topics like input validation, output encoding, and secure use of cryptographic APIs.
    • Threat Modeling: Regularly conduct threat modeling exercises to identify new potential threats and vulnerabilities.

  6. JSPatch Library Hardening (Medium Priority):

    • Contribute Security Fixes: If you identify any vulnerabilities in the JSPatch library itself, contribute fixes back to the open-source project.
    • Fork and Maintain: Consider forking the JSPatch repository and maintaining your own version with enhanced security controls. This gives you more control over the library's security.
    • Regular Audits: Conduct regular security audits of the JSPatch library code.

  7. Addressing the Questions:

    • Specific Objective-C APIs: A detailed list of exposed APIs is essential. This list should be minimized and rigorously reviewed.
    • Patch Deployment Frequency: Higher frequency increases the risk. More frequent deployments require more robust security controls and automation.
    • User Data Types: The sensitivity of user data dictates the level of protection required. Highly sensitive data (e.g., PII, financial data) requires strong encryption and access controls.
    • Third-Party Integrations: Each third-party integration introduces a new supply chain risk. These integrations need to be carefully assessed.
    • Private Key Management: Private keys should be stored in a Hardware Security Module (HSM) or a secure enclave if possible. If not, use strong encryption and access controls.
    • Networking Module Implementation: Details are needed to assess its security. Specifically, how is HTTPS implemented? Is certificate pinning used? What TLS configuration is used?
    • Logging/Monitoring: Existing infrastructure can be leveraged for runtime monitoring and anomaly detection. If none exists, it should be implemented.

This deep analysis provides a comprehensive overview of the security considerations for using JSPatch. The most critical takeaway is that while JSPatch offers a powerful mechanism for hotpatching, it introduces significant security risks that must be carefully addressed through a combination of secure coding practices, robust security controls, and ongoing monitoring. The recommendations provided are actionable and tailored to the specific challenges of JSPatch, aiming to minimize the attack surface and protect user data.