# Vulnerability Summary ## 1. Vulnerability Overview This is a **SSRF (Server-Side Request Forgery)** vulnerability. - **Description**: The application lacks effective validation and sanitization mechanisms when processing user-provided URLs, allowing attackers to construct malicious URLs that cause the server to initiate requests to targets specified by the attacker. - **Risk**: Attackers can exploit this vulnerability to scan internal network ports, access local file systems (e.g., `/etc/passwd`), retrieve cloud provider metadata (e.g., AWS/GCP metadata), access local services (e.g., Redis), or bypass restrictions via redirects. ## 2. Scope of Impact - **Affected Files**: - **Source (Entry Point)**: `app/api/audio_api.py` (Line 132) - Users provide URLs via HTTP requests. - **Sink (Exit Point)**: `app/services/file_service.py` (Line 129) - The URL is used in `requests.get(url)`. - **Attack Vectors**: - Internal network scanning (`http://192.168.1.1/admin`) - File system access (`file:///etc/passwd`) - Cloud metadata access (`http://169.254.169.254/latest/meta-data/`) - Local service access (`http://localhost:6379/`) - Redirect attacks (Valid URL that redirects to an internal resource) ## 3. Remediation Strategy Implement URL validation logic (`validate_url`) in `app/core/security.py` with the following strategies: - **Protocol Whitelist**: Allow only `http` and `https` protocols. - **Host Blacklist**: Explicitly block access to `localhost`, `127.0.0.1`, `0.0.0.0`, and cloud metadata addresses (`metadata.google.internal`, `169.254.169.254`). - **IP Address Check**: Resolve the domain name to an IP address and reject private IPs, loopback addresses, or link-local addresses. ## 4. Related Code (POC/Testing Code) **Remediation Implementation Code (`app/core/security.py`):** ```python from urllib.parse import urlparse from typing import Set ALLOWED_SCHEMES: Set[str] = {"http", "https"} BLOCKED_HOSTS: Set[str] = { "localhost", "127.0.0.1", "0.0.0.0", "metadata.google.internal", "169.254.169.254" } def validate_url(url: str) -> str: """ Validate URL to prevent SSRF attacks. Raises: ValidationError: If URL is potentially dangerous """ parsed = urlparse(url) # Check scheme if parsed.scheme not in ALLOWED_SCHEMES: raise ValidationError(f"URL scheme '{parsed.scheme}' not allowed") # Check for blocked hosts hostname = parsed.hostname or "" if hostname.lower() in BLOCKED_HOSTS: raise ValidationError(f"Access to '{hostname}' is not allowed") # Check for private IP ranges if is_private_ip(hostname): raise ValidationError(f"Access to private IP addresses is not allowed") return url def is_private_ip(hostname: str) -> bool: """Check if hostname resolves to a private IP address.""" import ipaddress try: ip = ipaddress.ip_address(hostname) return ip.is_private or ip.is_loopback or ip.is_link_local except ValueError: # Hostname might be a domain name, resolve it # Consider using dnspython for more robust DNS validation return False ``` **Test/Verification Code (`app/core/test/test_security.py`):** ```python import pytest from app.core.security import validate_url from app.core.exceptions import ValidationError @pytest.mark.parametrize("bad_url", [ "file:///etc/passwd", "http://localhost/admin", "http://127.0.0.1", "http://169.254.169.254/latest/meta-data/", "http://10.0.0.1/internal", "http://example.com/file" ]) def test_validate_url_rejects_dangerous_urls(bad_url): with pytest.raises(ValidationError): validate_url(bad_url) @pytest.mark.parametrize("good_url", [ "https://example.com/file.wav", "http://cdn.example.com/file.wav" ]) def test_validate_url_accepts_safe_urls(good_url): assert validate_url(good_url) == good_url ```