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 (FQDNs), URL, IP address, or IP Address ranges. If the location information is not validated against a variety of different possible encodings and formats, the adversary can use an alternate format to bypass application access control.
An adversary identifies an application server that applies a security policy based on the domain and application name. For example, the access control policy covers authentication and authorization for anyone accessing http://example.domain:8080/application. However, by using the IP address of the host instead (http://192.168.0.1:8080/application), the application authentication and authorization controls may be bypassed. The adversary 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 adversary has only to try IP address format combinations.
The adversary needs to have knowledge of an alternative IP address encoding that bypasses the access control policy of an application. Alternatively, the adversary can simply try to brute-force various encoding possibilities.
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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