Common Attack Pattern Enumeration and Classification
A Community Resource for Identifying and Understanding Attacks
This attack relies on the attacker using unexpected formats for representing IP addresses. Networked applications may expect network location information in a specific format, such as fully qualified domains names, URL, IP address, or IP Address ranges. The issue that the attacker can exploit is that these design assumptions may not be validated against a variety of different possible encodings and network address location formats. Applications that use naming for creating policy namespaces for managing access control may be susceptible to being queried directly by IP addresses, which is ultimately a more generally authoritative way of communicating on a network.
Alternative IP addresses can be used by the attacker to bypass application access control in order to gain access to data that is only protected by obscuring its location.
In addition this type of attack can be used as a reconnaissance mechanism to provide entry point information that the attacker gathers to penetrate deeper into the system.
An attacker identifies an application server that applies a security policy based on the domain and application name, so the access control policy covers authentication and authorization for anyone accessing http://example.domain:8080/application. However, by putting in the IP address of the host the application authentication and authorization controls may be bypassed http://192.168.0.1:8080/application. The attacker relies on the victim applying policy to the namespace abstraction and not having a default deny policy in place to manage exceptions.
Skill or Knowledge Level: Low
The attacker has only to try IP address combinations.
Ability to communicate with server. Optionally, ability to capture output directly through synchronous communication or other method such as FTP.
Design: Default deny access control policies
Design: Input validation routines should check and enforce both input data types and content against a positive specification. In regards to IP addresses, this should include the authorized manner for the application to represent IP addresses and not accept user specified IP addresses and IP address formats (such as ranges)
Implementation: Perform input validation for all remote content.
Varies with instantiation of attack pattern. Malicious payload may be passed directly from application client, such as the web browser.
[R.4.1] [REF-2] G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. February 2004.
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