T05 · Unauthorized Access and Privilege Escalation
- Location
scripts/fetch_url.py:39- Finding
Unrestricted URL Fetching Enables Server-Side Request Forgery
- Content
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Vulnerability Details
File Location:
scripts/fetch_url.py, lines 39–58
Vulnerability Type: Server-Side Request Forgery (SSRF)
Risk Level: HighVulnerable Code
python def fetch_url(url, max_chars=None, timeout=30): """ Fetch and parse web content. Args: url: Web page URL max_chars: Maximum number of returned characters timeout: Request timeout """ headers = { 'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36' } try: response = requests.get(url, headers=headers, timeout=timeout, verify=False)Technical Analysis
The
fetch_urlfunction passes a caller-controlled URL directly torequests.getwithout validating its scheme, hostname, resolved IP address, destination port, or redirect targets.The Requests library follows redirects by default. Consequently, validating only an initial URL would also be insufficient: an external server could redirect the request to a loopback, private, link-local, reserved, or cloud metadata address.
This creates an SSRF primitive in any environment where an untrusted party can provide a URL directly or influence a search result processed by
search_and_fetch.py.Attack Path
- An attacker provides a URL to
scripts/fetch_url.py, or causes a malicious URL to appear in search results processed byscripts/search_and_fetch.py. - The URL references an internal destination directly, such as a loopback/private address, or references an external server that redirects to one.
requests.getsends the request from the Agent host without destination validation.- The response is parsed and returned through the script's text or JSON output.
- The attacker may use the returned content to enumerate internal services or obtain information from resources unavailable from the public network.
...[truncated 625 chars]
- An attacker provides a URL to
- Remediation
View remediation
Remediation Suggestions
- Permit only explicitly supported schemes, normally
httpsand, if necessary,http. - Reject URLs containing embedded credentials, malformed hostnames, unsupported ports, or ambiguous IP representations.
- Resolve the hostname before connecting and reject loopback, private, link-local, multicast, reserved, unspecified, and metadata-service addresses for both IPv4 and IPv6.
- Disable automatic redirects or validate and resolve every redirect destination before following it.
- Protect against DNS rebinding by ensuring the validated address is the address used for the connection.
- Prefer an explicit domain allowlist when the expected destinations are known.
- Route outbound traffic through a controlled proxy or firewall that blocks internal address ranges.
- Apply response-size and streaming limits to prevent excessive memory consumption while retrieving untrusted resources.
- Permit only explicitly supported schemes, normally
