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CAPEC-4: Using Alternative IP Address Encodings

Using Alternative IP Address Encodings
Definition in a New Window Definition in a New Window
Attack Pattern ID: 4
Abstraction: Detailed
Status: Draft
Completeness: Complete
Presentation Filter:
+ Summary

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.

+ Attack Prerequisites
  • The target software must fail to anticipate all of the possible valid encodings of an IP/web address.

  • The adversary must have the ability to communicate with the server.

+ Typical Severity


+ Typical Likelihood of Exploit

Likelihood: Medium

+ Methods of Attack
  • Injection
  • Protocol Manipulation
  • API Abuse
+ Examples-Instances


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 (, 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.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

The adversary has only to try IP address format combinations.

+ Resources Required

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.

+ Solutions and Mitigations

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.

+ Attack Motivation-Consequences
ScopeTechnical ImpactNote
Gain privileges / assume identity
+ Injection Vector

Malicious input delivered through standard input

+ Payload

Varies with instantiation of attack pattern. Malicious payload may be passed directly from application client, such as the web browser.

+ Activation Zone

Client machine and client network

+ Payload Activation Impact

Enables attacker to view and access unexpected network services.

+ Purposes
  • Penetration
+ CIA Impact
Confidentiality Impact: MediumIntegrity Impact: MediumAvailability Impact: High
+ Technical Context
Architectural Paradigms
+ References
[R.4.1] [REF-2] G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. February 2004.
+ Content History
CAPEC Content TeamThe MITRE Corporation2014-06-23Internal_CAPEC_Team
CAPEC Content TeamThe MITRE Corporation2017-08-04Updated Attack_Prerequisites, Attacker_Skills_or_Knowledge_Required, Description Summary, Examples-Instances, Resources_RequiredInternal

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Page Last Updated or Reviewed: August 04, 2017