CWE-643 Detail

The product uses external input to dynamically construct an XPath expression used to retrieve data from an XML database, but it does not neutralize or incorrectly neutralizes that input. This allows an attacker to control the structure of the query.

The net effect is that the attacker will have control over the information selected from the XML database and may use that ability to control application flow, modify logic, retrieve unauthorized data, or bypass important checks (e.g. authentication).

Modes Of Introduction

Implementation : REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Language

Class: Not Language-Specific (Undetermined)

Common Consequences

Potential Mitigations

Phases : Implementation
Use parameterized XPath queries (e.g. using XQuery). This will help ensure separation between data plane and control plane.
Phases : Implementation
Properly validate user input. Reject data where appropriate, filter where appropriate and escape where appropriate. Make sure input that will be used in XPath queries is safe in that context.

Detection Methods

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Effectiveness : High

Vulnerability Mapping Notes

Justification : This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comment : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

NotesNotes

This weakness is similar to other weaknesses that enable injection style attacks, such as SQL injection, command injection and LDAP injection. The main difference is that the target of attack here is the XML database.

References

REF-531

XPath Injection
Web Application Security Consortium.
http://projects.webappsec.org/w/page/13247005/XPath%20Injection

REF-62

The Art of Software Security Assessment
Mark Dowd, John McDonald, Justin Schuh.

Submission

Modifications