mitigations.md

Mitigation Strategies Analysis for flexmonkey/blurable

Mitigation Strategy: Strict Input Validation and Sanitization (as it pertains to blurable)

• Description:

  1. Identify Supported Formats: Determine which image formats blurable actually supports. This might require examining the library's source code or documentation.
  2. Implement Format Verification: Before passing any image data to blurable, verify that the image format is among those supported by the library. Use a robust method (e.g., parsing the image header) to confirm the format, not just file extensions.
  3. Set Dimension Limits: Determine the maximum image dimensions that blurable can handle efficiently without causing performance issues or crashes. This might involve testing with various image sizes. Reject any image exceeding these limits before calling blurable.
  4. Implement Rejection Mechanism: If an image is rejected (invalid format or excessive dimensions), ensure that the rejection occurs before any interaction with blurable.

• Threats Mitigated:

  • Malicious Image Exploits (Severity: High): If blurable has vulnerabilities in its image parsing, passing a malformed image could trigger them. Pre-validation prevents this.
  • Denial of Service (DoS) via Large Images (Severity: Medium): blurable might be inefficient or crash when processing extremely large images. Pre-validation of dimensions prevents this.
  • Resource Exhaustion (Severity: Medium): Similar to DoS.

• Impact:

  • Malicious Image Exploits: Risk reduction: Very High.
  • Denial of Service (DoS): Risk reduction: High.
  • Resource Exhaustion: Risk reduction: High.

• Currently Implemented:

  • Format validation using CGImageSource (iOS) in ImageValidator.swift.
  • Dimension limits checked in UploadService.java before processing.

• Missing Implementation:

  • Verification that the format validation logic specifically aligns with the formats supported by blurable.
  • Dimension limits might need adjustment based on blurable's specific limitations.

Mitigation Strategy: Resource Consumption Limits (focused on blurable's processing)

• Description:

  1. Set Timeouts: Specifically when calling blurable's blurring functions, set a strict timeout. This timeout should be based on the expected processing time for the largest allowed image size and the most computationally intensive blur settings.
  2. Implement Timeout Handling: If the timeout is reached while blurable is processing, ensure that the operation is immediately terminated and any resources held by blurable are released. This might involve platform-specific mechanisms to interrupt the blurring process.
  3. Create Blurring Queue and Configure Concurrency: Use a queue to manage calls to blurable. Limit the number of concurrent calls to blurable to prevent resource exhaustion. This is crucial if blurable is not thread-safe or if it consumes significant resources.

• Threats Mitigated:

  • Denial of Service (DoS) via Long-Running Operations (Severity: Medium): blurable might have performance bottlenecks or vulnerabilities that could be exploited to cause long processing times.
  • Resource Exhaustion (Severity: Medium): Even without a full DoS, excessive resource consumption by blurable can impact the application.
  • Application Unresponsiveness (Severity: Medium):

• Impact:

  • Denial of Service (DoS): Risk reduction: High.
  • Resource Exhaustion: Risk reduction: High.
  • Application Unresponsiveness: Risk reduction: High.

• Currently Implemented:

  • Basic timeout (10 seconds) implemented in BlurService.swift.
  • A simple DispatchQueue is used, but without concurrency limits.

• Missing Implementation:

  • The timeout value needs to be specifically tuned based on blurable's performance characteristics.
  • Strict concurrency limits on the DispatchQueue are missing, specifically for calls to blurable.
  • Robust handling of blurable termination on timeout.

Mitigation Strategy: Preventing Information Leakage Through Blurring (controlling blurable's parameters)

• Description:

  1. Define Blurring Profiles: Instead of allowing arbitrary adjustment of blurable's parameters (e.g., radius, blur type), create a set of predefined blurring profiles. Each profile should have fixed parameter values that are passed to blurable.
  2. Restrict User Input: The application's user interface should only allow users to select from these predefined profiles. Do not expose blurable's raw parameters directly to the user.
  3. Audit Blurring Results: Ensure that the parameters passed to blurable consistently produce the intended level of blurring and do not inadvertently reveal information.

• Threats Mitigated:

  • Information Disclosure via Differential Blurring (Severity: Medium): Allowing users to control blurable's parameters directly could lead to inconsistent blurring that reveals information.
  • Inadvertent Information Leakage (Severity: Low/Medium):

• Impact:

  • Information Disclosure: Risk reduction: High.
  • Inadvertent Information Leakage: Risk reduction: High.

• Currently Implemented:

  • No predefined blurring profiles. Users can adjust the blur radius freely, directly affecting the parameter passed to blurable.

• Missing Implementation:

  • Complete redesign of the blurring interface to use predefined profiles, controlling the values passed to blurable.

Mitigation Strategy: Parameter Sanitization and Validation (for blurable's input)

• Description:

  1. Identify Parameters: Identify all parameters that the application passes to blurable.
  2. Define Allowed Values: For each parameter, define the allowed range of values or a whitelist of specific values. This should be based on blurable's documentation and expected behavior.
  3. Implement Validation: Before calling any blurable function, validate all parameters against the allowed values. Use strict type checking.
  4. Reject Invalid Parameters: If any parameter is invalid, reject the entire operation before calling blurable. Do not attempt to modify the parameter.

• Threats Mitigated:

  • Filter Manipulation Attacks (Severity: Medium): Passing unexpected or extreme values to blurable's parameters could cause crashes, unexpected behavior, or potentially exploit vulnerabilities.
  • Unexpected Behavior (Severity: Low):

• Impact:

  • Filter Manipulation Attacks: Risk reduction: High.
  • Unexpected Behavior: Risk reduction: High.

• Currently Implemented:

  • Basic range check for blur radius in BlurSettingsViewController.swift.

• Missing Implementation:

  • Comprehensive validation for all parameters passed to blurable.
  • Stricter type checking.
  • Use of whitelists where appropriate.
  • Centralized validation logic to ensure consistency.