WEEK 7: Implement Policy Interceptor and Agent Profiles for FinBot Security Framework

[Jean-Regis-M]

Summary

This week's work focused on implementing the core security infrastructure for the FinBot project by developing the Policy Interceptor and predefined Agent Profiles as outlined in the GSoC proposal. The implementation addresses OWASP ASI02 (Tool Misuse), ASI03 (Excessive Agency), and ASI07 (Prompt Injection) through least-privilege access controls and intent-based security mechanisms.

Changes Made

Core Implementation (finbot/aegis/policy/)

1. __init__.py - Package initialization exporting all policy components
2. agent_profiles.py - Defines six least-agency agent profiles:
   • Data Analyst: Read-only access to financial data tools
   • Report Generator: Limited write access for report generation
   • API Integrator: Controlled access to external API wrappers
   • Security Auditor: Specialized permissions for security scanning tools
   • Workflow Orchestrator: Privileges to manage and coordinate workflows
   • Research Assistant: Broad but monitored access for research tasks
3. interceptor.py - Implements MCPPolicyInterceptor with:
   • Real-time MCP tool call interception
   • Policy enforcement based on agent profiles
   • Resource limit enforcement (rate limiting)
   • Intent capsule creation (stubbed for Week 8)
   • Policy violation logging and metrics collection
   • Integration hooks for memory namespace provenance (stubbed for Week 8)

Week 8 Stubs (Forward Compatibility)

• capsule.py - Stub for IntentCapsule with HMAC signing/validation interface
• memory.py - Stub for MemoryNamespaceManager with provenance tracking interface

Comprehensive Test Suite

• tests/unit/aegis/test_policy_interceptor.py - Full test coverage including:
  • Tool authorization and blocking tests
  • Resource limit enforcement validation
  • Agent profile behavior verification
  • Metrics reporting accuracy
  • Policy violation logging checks

Key Features

• Least-Privilege Access Control: Each agent type operates with precisely defined tool allowances
• Dynamic Policy Enforcement: Interceptor wraps tool execution with real-time policy checks
• Rate Limiting: Configurable resource limits prevent abuse and ensure fair usage
• Audit Ready: Comprehensive logging of all policy decisions for compliance
• Extensible Design: Clean separation of concerns with stubs prepared for Week 8 enhancements
• Security Framework Alignment: Directly addresses OWASP ASIS Top 10 for LLM Applications

Testing Status

✅ All unit tests passing
✅ Edge cases covered (invalid profiles, exceeded limits, unauthorized tool access)
✅ Metrics collection verified
✅ Agent profile combinations tested

Next Steps (Week 8)

In Week 8, the stub files will be replaced with full implementations featuring:

• Cryptographic HMAC signing and validation for intent capsules
• Secure memory namespace isolation with provenance tracking
• Tamper-evident audit log generation
• Integration with the policy interceptor for end-to-end security

Acknowledgments

Special thanks to my mentors @mekaizen and @steadhac for their continuous guidance, insightful feedback, and unwavering support throughout this GSoC journey. Their expertise has been instrumental in shaping this security-focused implementation.

[mekaizen]

Multiple agent profiles define hardcoded default secrets such as:

Do not embed predictable default secrets in code. Load them from configuration or generate cryptographically secure secrets.

import secrets

secret_key = (
settings.get("AEGIS_AGENT_SECRET")
or secrets.token_hex(32)
)

or fail fast
secret = settings.get("AEGIS_AGENT_SECRET")

if not secret:
raise RuntimeError(
"AEGIS_AGENT_SECRET must be configured."
)

secret_key = secret

[Jean-Regis-M]

Thank you for your review and suggestions, @mekaizen! I've updated the agent profiles to remove hardcoded secrets and instead load the secret key from configuration (with a fallback to a cryptographically generated secret for development). The changes are in line with the project's security best practices. Please let me know if you have any further feedback.