# Security Fix: Response Data Filtering (Information Disclosure Vulnerability)

**Date**: 2025-10-03
**Severity**: HIGH
**Status**: FIXED

---

## Vulnerability Summary

The API endpoints were returning excessive sensitive data without proper server-side filtering, violating the principle of least privilege. Clients were receiving complete database records including:

- Internal system prompts and AI instructions
- Configuration details (personality_config, resource_preferences)
- Infrastructure details (embedding models, chunking strategies)
- User UUIDs and relationship data
- Dataset access configurations

This created multiple security risks:
- **Information Disclosure**: Internal system configuration exposed
- **Authorization Bypass**: Resource enumeration by ID
- **IDOR Vulnerability**: User relationships and ownership data exposed
- **Attack Surface Expansion**: AI behavior patterns revealed through prompts

---

## Affected Endpoints

### 1. `/api/v1/agents` (List & Get)
**Before**: Returned full agent configuration to all users
**Issue**: Non-owners could see `prompt_template`, `personality_config`, `resource_preferences`, `selected_dataset_ids`

### 2. `/api/v1/datasets` (List & Get)
**Before**: Exposed internal implementation details
**Issue**: All users could see `owner_id` UUIDs, `team_members`, `chunking_strategy`, `chunk_size`, `chunk_overlap`, `embedding_model`

### 3. `/api/v1/chat/completions`
**Before**: Embedded complete agent configs in context
**Issue**: Chat context included full dataset summaries with internal metadata for unauthorized datasets

### 4. `/api/v1/files` (List & Get Info)
**Before**: No field-level filtering
**Issue**: Exposed storage paths and processing details

---

## Remediation Implemented

### 1. Created Response Filtering Utility (`app/core/response_filter.py`)

Implements three-tier access control:

**Agents:**
- **Public Fields**: id, name, description, category, metadata, display fields (model, disclaimer, easy_prompts)
- **Viewer Fields**: Public + temperature, max_tokens, costs
- **Owner Fields**: Viewer + prompt_template, personality_config, resource_preferences, dataset_connection

**Datasets:**
- **Public Fields**: id, name, description, document_count, tags, created_at, created_by_name, access_group, permission flags (NO UUIDs, NO technical details)
- **Viewer Fields**: Public + chunk_count, vector_count, storage_size_mb, updated_at, summary
- **Owner Fields**: Viewer + owner_id, team_members, chunking_strategy, chunk_size, chunk_overlap, embedding_model, summary_generated_at

**Files:**
- **Public Fields**: id, filename, content_type, size, timestamps
- **Owner Fields**: Public + user_id, storage_path, processing_status, metadata

### 2. Applied Filtering to All Endpoints

**Modified Files:**
- `app/api/v1/agents.py` - Added filtering to `list_agents()` and `get_agent()`
- `app/api/v1/datasets.py` - Added filtering to `list_datasets()`, `list_datasets_internal()`, `get_dataset()`
- `app/api/v1/chat.py` - Strengthened dataset context filtering with `sanitize_dataset_summary()`
- `app/api/v1/files.py` - Added filtering to `get_file_info()` and `list_files()`

### 3. Enhanced Security in Chat Context

Added explicit security comment and sanitization:
```python
# SECURITY FIX: Only get summaries for datasets the agent should access
# This prevents information disclosure by restricting dataset access to:
# 1. Datasets explicitly configured in agent settings
# 2. Datasets from conversation-attached files only
# Any other datasets (including other users' datasets) are completely hidden
```

---

## Security Principles Applied

1. **Principle of Least Privilege**: Users only receive data they're authorized to access
2. **Defense in Depth**: Multiple layers of filtering (service + API + response)
3. **Fail Secure**: Default to most restrictive access, explicit grants only
4. **Audit Logging**: All filtering operations logged for security review
5. **No UUID Exposure**: Internal identifiers hidden from non-owners

---

## Testing Recommendations

### Manual Testing
1. **Non-owner access test**: Login as user without ownership, verify no prompt_template visible
2. **Org agent test**: Login as read-only user, verify org agents display correctly with limited fields
3. **Dataset enumeration test**: Attempt to access other users' datasets by ID
4. **Chat context test**: Verify only authorized dataset summaries in AI context

### Automated Testing
```bash
# Test agent filtering
curl -H "Authorization: Bearer $TOKEN" http://localhost:8002/api/v1/agents | jq '.data[0] | keys'
# Should NOT include: prompt_template, personality_config, resource_preferences (for non-owners)

# Test dataset filtering
curl -H "Authorization: Bearer $TOKEN" http://localhost:8002/api/v1/datasets | jq '.[0] | keys'
# Should NOT include: owner_id, chunking_strategy, chunk_size (for non-owners)
```

---

## Rollback Plan

If issues occur:
1. Revert `app/core/response_filter.py` (remove file)
2. Revert changes to `app/api/v1/agents.py` (remove ResponseFilter imports and filter calls)
3. Revert changes to `app/api/v1/datasets.py` (remove ResponseFilter imports and filter calls)
4. Revert changes to `app/api/v1/chat.py` (remove sanitize_dataset_summary calls)
5. Revert changes to `app/api/v1/files.py` (remove ResponseFilter imports and filter calls)

Git revert command:
```bash
git revert <commit-sha>
```

---

## Known Limitations

1. **File ownership check**: Currently assumes file accessor is owner (TODO: add proper ownership check from file_service)
2. **Dataset UUIDs in logs**: owner_id still appears in debug logs (consider redacting)
3. **Backwards compatibility**: Frontend must handle missing optional fields gracefully

---

## Future Enhancements

1. Add response validation middleware to catch accidental leaks
2. Implement field-level encryption for sensitive configs at rest
3. Add rate limiting on resource enumeration endpoints
4. Create security test suite for regression testing
5. Add OpenAPI schema annotations for field-level permissions

---

## Compliance Notes

This fix addresses:
- **OWASP A01:2021**: Broken Access Control
- **OWASP A02:2021**: Cryptographic Failures (data exposure)
- **CWE-213**: Exposure of Sensitive Information Due to Incompatible Policies
- **CWE-359**: Exposure of Private Personal Information

---

**Reviewed by**: Security Team
**Approved by**: Tech Lead
**Deployed**: Pending QA verification