CAPEC-34: HTTP Response Splitting

<p>An adversary manipulates and injects malicious content, in the form of secret unauthorized HTTP responses, into a single HTTP response from a vulnerable or compromised back-end HTTP agent (e.g., web server) or into an already spoofed HTTP response from an adversary controlled domain/site.<p><p>See CanPrecede relationships for possible consequences.<p>
Extended Description

Malicious user input is injected into various standard and/or user defined HTTP headers within a HTTP Response through use of Carriage Return (CR), Line Feed (LF), Horizontal Tab (HT), Space (SP) characters as well as other valid/RFC compliant special characters, and unique character encoding.

A single HTTP response ends up being split as two or more HTTP responses by the targeted client HTTP agent parsing the original maliciously manipulated HTTP response. This allows malicious HTTP responses to bypass security controls in order to implement malicious actions and provide malicious content that allows access to sensitive data and to compromise applications and users. This is performed by the abuse of interpretation and parsing discrepancies in different intermediary HTTP agents (load balancer, reverse proxy, web caching proxies, application firewalls, etc.) or client HTTP agents (e.g., web browser) in the path of the malicious HTTP responses.

This attack is usually the result of the usage of outdated or incompatible HTTP protocol versions as well as lack of syntax checking and filtering of user input in the HTTP agents receiving HTTP messages in the path.

This differs from CAPEC-105 HTTP Request Splitting, which is usually an attempt to compromise a back-end HTTP agent via HTTP Request messages. HTTP Response Splitting is an attempt to compromise aclient agent (e.g., web browser)by sending malicious content in HTTP responses from back-end HTTP infrastructure.

HTTP Smuggling (CAPEC-33 and CAPEC-273) is different from HTTP Splitting due to the fact it relies upon discrepancies in the interpretation of various HTTP Headers and message sizes and not solely user input of special characters and character encoding. HTTP Smuggling was established to circumvent mitigations against HTTP Request Splitting techniques.

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This table shows the other attack patterns and high level categories that are related to this attack pattern.

  • A vulnerable or compromised server or domain/site capable of allowing adversary to insert/inject malicious content that will appear in the server's response to target HTTP agents (e.g., proxies and users' web browsers).
  • Differences in the way the two HTTP agents parse and interpret HTTP requests and its headers.
  • HTTP headers capable of being user-manipulated.
  • HTTP agents running on HTTP/1.0 or HTTP/1.1 that allow for Keep Alive mode, Pipelined queries, and Chunked queries and responses.
Skills required

This table shows the other attack patterns and high level categories that are related to this attack pattern.

  • Medium Detailed knowledge on HTTP protocol: request and response messages structure and usage of specific headers.
  • Medium Detailed knowledge on how specific HTTP agents receive, send, process, interpret, and parse a variety of HTTP messages and headers.
  • Medium Possess knowledge on the exact details in the discrepancies between several targeted HTTP agents in path of an HTTP message in parsing its message structure and individual headers.
Taxonomy mappings

Mappings to ATT&CK, OWASP and other frameworks.

Resources required

Tools capable of monitoring HTTP messages, and crafting malicious HTTP messages and/or injecting malicious content into HTTP messages.

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Latest DB Update: Jul. 22, 2024 8:45