CAPEC-160 Exploit Script-Based APIs – Attack Pattern Analysis

CAPEC-160 Metadata

Likelihood of Attack

Medium

Typical Severity

Medium

Overview

Summary

Some APIs support scripting instructions as arguments. Methods that take scripted instructions (or references to scripted instructions) can be very flexible and powerful. However, if an attacker can specify the script that serves as input to these methods they can gain access to a great deal of functionality. For example, HTML pages support <script> tags that allow scripting languages to be embedded in the page and then interpreted by the receiving web browser. If the content provider is malicious, these scripts can compromise the client application. Some applications may even execute the scripts under their own identity (rather than the identity of the user providing the script) which can allow attackers to perform activities that would otherwise be denied to them.

Prerequisites

The target application must include the use of APIs that execute scripts. The target application must allow the attacker to provide some or all of the arguments to one of these script interpretation methods and must fail to adequately filter these arguments for dangerous or unwanted script commands.

Execution Flow

Step	Phase	Description	Techniques
1	Explore	[Identify API] Discover an API of interest by exploring application documentation or observing responses to API calls	Search via internet for known, published APIs that support scripting instructions as arguments
2	Experiment	[Test simple script] Adversaries will attempt to give a smaller script as input to the API, such as simply printing to the console, to see if the attack is viable.	Create a general script to be taken as input by the API
3	Exploit	[Give malicious scripting instructions to API] Adversaries will now craft custom scripts to do malicious behavior. Depending on the setup of the application this script could be run with user or admin level priveleges.	Crafting a malicious script to be run on a system based on priveleges and capabilities of the system

Potential Solutions / Mitigations

No specific solutions listed.

Related Weaknesses (CWE)

CWE ID	Description
CWE-346	Origin Validation Error

Related CAPECs

CAPEC ID	Description
CAPEC-113	An adversary manipulates the use or processing of an interface (e.g. Application Programming Interface (API) or System-on-Chip (SoC)) resulting in an adverse impact upon the security of the system implementing the interface. This can allow the adversary to bypass access control and/or execute functionality not intended by the interface implementation, possibly compromising the system which integrates the interface. Interface manipulation can take on a number of forms including forcing the unexpected use of an interface or the use of an interface in an unintended way.

CAPEC ID

Description

CAPEC-113

An adversary manipulates the use or processing of an interface (e.g. Application Programming Interface (API) or System-on-Chip (SoC)) resulting in an adverse impact upon the security of the system implementing the interface. This can allow the adversary to bypass access control and/or execute functionality not intended by the interface implementation, possibly compromising the system which integrates the interface. Interface manipulation can take on a number of forms including forcing the unexpected use of an interface or the use of an interface in an unintended way.

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