CAPEC-250 XML Injection – Attack Pattern Analysis

CAPEC-250 Metadata

Likelihood of Attack

High

Typical Severity

High

Overview

Summary

An attacker utilizes crafted XML user-controllable input to probe, attack, and inject data into the XML database, using techniques similar to SQL injection. The user-controllable input can allow for unauthorized viewing of data, bypassing authentication or the front-end application for direct XML database access, and possibly altering database information.

Prerequisites

XML queries used to process user input and retrieve information stored in XML documents User-controllable input not properly sanitized

Execution Flow

Step	Phase	Description	Techniques
1	Explore	[Survey the Target] Using a browser or an automated tool, an adversary records all instances of user-controllable input used to contruct XML queries	Use an automated tool to record all instances of user-controllable input used to contruct XML queries. Use a browser to manually explore the website and analyze how the application processes inputs.
2	Experiment	[Determine the Structure of Queries] Using manual or automated means, test inputs found for XML weaknesses.	Use XML reserved characters or words, possibly with other input data to attempt to cause unexpected results and identify improper input validation.
3	Exploit	[Inject Content into XML Queries] Craft malicious content containing XML expressions that is not validated by the application and is executed as part of the XML queries.	Use the crafted input to execute unexpected queries that can disclose sensitive database information to the attacker.

Potential Solutions / Mitigations

Strong input validation - All user-controllable input must be validated and filtered for illegal characters as well as content that can be interpreted in the context of an XML data or a query. Use of custom error pages - Attackers can glean information about the nature of queries from descriptive error messages. Input validation must be coupled with customized error pages that inform about an error without disclosing information about the database or application.

Related Weaknesses (CWE)

CWE ID	Description
CWE-20	Improper Input Validation
CWE-74	Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-91	XML Injection (aka Blind XPath Injection)
CWE-707	Improper Neutralization

Related CAPECs

CAPEC ID	Description
CAPEC-248	An adversary looking to execute a command of their choosing, injects new items into an existing command thus modifying interpretation away from what was intended. Commands in this context are often standalone strings that are interpreted by a downstream component and cause specific responses. This type of attack is possible when untrusted values are used to build these command strings. Weaknesses in input validation or command construction can enable the attack and lead to successful exploitation.

CAPEC ID

Description

CAPEC-248

An adversary looking to execute a command of their choosing, injects new items into an existing command thus modifying interpretation away from what was intended. Commands in this context are often standalone strings that are interpreted by a downstream component and cause specific responses. This type of attack is possible when untrusted values are used to build these command strings. Weaknesses in input validation or command construction can enable the attack and lead to successful exploitation.

Taxonomy Mappings

Taxonomy: WASC

Entry ID	Entry Name
23	XML Injection

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