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Description
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
Modes of Introduction:
– Architecture and Design
Likelihood of Exploit:
Related Weaknesses
CWE-441
CWE-610
Consequences
Confidentiality: Read Application Data
Integrity: Execute Unauthorized Code or Commands
Potential Mitigations
CVE References
- CVE-2002-1484
- Web server allows attackers to request a URL from another server, including other ports, which allows proxied scanning.
- CVE-2010-1637
- Web-based mail program allows internal network scanning using a modified POP3 port number.
- CVE-2009-0037
- URL-downloading library automatically follows redirects to file:// and scp:// URLs
