Chi tiết CAPEC-207

An adversary removes or disables functionality on the client that the server assumes to be present and trustworthy.

Luồng thực thi

[Probing] The adversary probes, through brute-forcing, reverse-engineering or other similar means, the functionality on the client that server assumes to be present and trustworthy.

• The adversary probes by exploring an application's functionality and its underlying mapping to server-side components.
• The adversary reverse engineers client-side code to identify the functionality that the server relies on for the proper or secure operation.

[Determine which functionality to disable or remove] The adversary tries to determine which functionality to disable or remove through reverse-engineering from the list of functionality identified in the Explore phase.

• The adversary reverse engineers the client-side code to determine which functionality to disable or remove.

[Disable or remove the critical functionality from the client code] Once the functionality has been determined, the adversary disables or removes the critical functionality from the client code to perform malicious actions that the server believes are prohibited.

• The adversary disables or removes the functionality from the client-side code to perform malicious actions, such as sending of dangerous content (such as scripts) to the server.

Điều kiện tiên quyết

The targeted server must assume the client performs important actions to protect the server or the server functionality. For example, the server may assume the client filters outbound traffic or that the client performs all price calculations correctly. Moreover, the server must fail to detect when these assumptions are violated by a client.

Kỹ năng cần thiết

To reverse engineer the client-side code to disable/remove the functionality on the client that the server relies on.
The adversary installs a web tool that allows scripts or the DOM model of web-based applications to be modified before they are executed in a browser. GreaseMonkey and Firebug are two examples of such tools.

Tài nguyên cần thiết

The adversary must have access to a client and be able to modify the client behavior, often through reverse engineering. If the server is assuming specific client functionality, this usually means the server only recognizes a specific client application, rather than a broad class of client applications. Reverse engineering tools would likely be necessary.

Các biện pháp giảm thiểu

Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side.
Design: Ship client-side application with integrity checks (code signing) when possible.
Design: Use obfuscation and other techniques to prevent reverse engineering the client code.

Điểm yếu liên quan

Tài liệu tham khảo

REF-75

Wikipedia
http://en.wikipedia.org/wiki/Greasemonkey

REF-76

Firebug
http://getfirebug.com/

REF-77

Mozilla Firefox Add-ons
https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/

Gửi

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