Attack Surface: Model Poisoning/Backdooring
- Description: An attacker replaces a legitimate TTS model with a malicious one, or modifies an existing model to introduce harmful behavior.
- TTS Contribution: The core functionality of Coqui TTS relies on pre-trained or fine-tuned models. These models are the direct target.
- Example: An attacker provides a poisoned model that subtly changes the pronunciation of certain words to spread misinformation, or inserts barely audible commands.
- Impact: Loss of data integrity, manipulation of generated speech, potential execution of arbitrary commands (if output is fed to a system that interprets commands), reputational damage.
- Risk Severity: Critical
- Mitigation Strategies:
- Trusted Sources: Download models only from the official Coqui repository or a meticulously vetted internal source.
- Checksum Verification: Always verify the SHA-256 checksum of downloaded models against the official checksum. Reject any mismatch.
- Signature Verification: If Coqui provides signed models, verify the digital signature before loading.
- Regular Audits: Periodically re-verify the integrity of deployed models.
- Sandboxing (Advanced): Run the model inference in a highly restricted, isolated environment.
Attack Surface: Adversarial Examples (Model Evasion)
- Description: An attacker crafts specific input text designed to cause the TTS model to malfunction, produce unexpected output, or consume excessive resources.
- TTS Contribution: The TTS engine's core function is to process text input and generate audio. This input processing is directly vulnerable.
- Example: An attacker inputs a string of carefully chosen Unicode characters that cause the model to generate extremely high-frequency sounds or enter an infinite loop.
- Impact: Denial-of-service, unexpected audio output, potential hardware damage (extreme cases), resource exhaustion.
- Risk Severity: High
- Mitigation Strategies:
- Input Length Limits: Enforce strict maximum lengths for input text.
- Character Filtering: Restrict the allowed character set. Block unusual Unicode characters.
- Input Normalization: Normalize input text before processing.
- Rate Limiting: Limit the number of TTS requests per user/IP.
- Robustness Training (Advanced): Train the model with adversarial examples.
Attack Surface: Denial-of-Service (DoS) via Resource Exhaustion
- Description: An attacker overwhelms the TTS system with requests, or sends requests designed to consume excessive resources.
- TTS Contribution: TTS processing, especially with deep learning models, is computationally expensive. This makes the TTS engine itself a direct target.
- Example: An attacker sends thousands of simultaneous requests or requests with extremely long input texts.
- Impact: Service unavailability, disruption of service for legitimate users.
- Risk Severity: High
- Mitigation Strategies:
- Rate Limiting (Essential): Implement strict rate limiting per user/IP.
- Input Length Limits (Essential): Enforce strict limits on input text length.
- Resource Quotas: Set resource limits (CPU, memory) for the TTS process/container.
- Timeouts: Implement timeouts for TTS requests.
- Load Balancing: Distribute requests across multiple servers.
- Asynchronous Processing: Use asynchronous task queues.
Attack Surface: Dependency Vulnerabilities
- Description: Vulnerabilities in the libraries that Coqui TTS depends on (e.g., PyTorch, TensorFlow) could be exploited.
- TTS Contribution: Coqui TTS, relies on a complex web of dependencies. These dependencies are a potential source of vulnerabilities directly impacting TTS.
- Example: A vulnerability is discovered in a specific version of PyTorch that allows for remote code execution. An attacker exploits this vulnerability to gain control of the server running Coqui TTS.
- Impact: Remote code execution, system compromise, data breach.
- Risk Severity: High to Critical (depending on the vulnerability)
- Mitigation Strategies:
- Dependency Management: Use a robust dependency management system.
- Vulnerability Scanning: Regularly scan dependencies for known vulnerabilities.
- Prompt Updates: Keep dependencies up-to-date.
- Dependency Pinning: Pin dependency versions (balance with security updates).
- Vendor Advisories: Monitor security advisories from dependency vendors.