CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
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ID

CWE-112: Missing XML Validation

Weakness ID: 112
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software accepts XML from an untrusted source but does not validate the XML against the proper schema.
+ Extended Description
Most successful attacks begin with a violation of the programmer's assumptions. By accepting an XML document without validating it against a DTD or XML schema, the programmer leaves a door open for attackers to provide unexpected, unreasonable, or malicious input.
+ Relationships

The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass20Improper Input Validation
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfClassClass20Improper Input Validation
+ Relevant to the view "Seven Pernicious Kingdoms" (CWE-700)
NatureTypeIDName
ChildOfClassClass20Improper Input Validation
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Implementation
+ Applicable Platforms
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
Integrity

Technical Impact: Unexpected State

+ Demonstrative Examples

Example 1

The following code loads and parses an XML file.

(bad)
Example Language: Java 
// Read DOM
try {
...
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setValidating( false );
....
c_dom = factory.newDocumentBuilder().parse( xmlFile );

} catch(Exception ex) {
...

}

The XML file is loaded without validating it against a known XML Schema or DTD.

Example 2

The following code creates a DocumentBuilder object to be used in building an XML document.

(bad)
Example Language: Java 
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
builderFactory.setNamespaceAware(true);
DocumentBuilder builder = builderFactory.newDocumentBuilder();

The DocumentBuilder object does not validate an XML document against a schema, making it possible to create an invalid XML document.

+ Potential Mitigations

Phase: Architecture and Design

Strategy: Input Validation

Always validate XML input against a known XML Schema or DTD. It is not possible for an XML parser to validate all aspects of a document's content because a parser cannot understand the complete semantics of the data. However, a parser can do a complete and thorough job of checking the document's structure and therefore guarantee to the code that processes the document that the content is well-formed.
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness exists independent of other weaknesses)
+ Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfCategoryCategory990SFP Secondary Cluster: Tainted Input to Command
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
7 Pernicious KingdomsMissing XML Validation
Software Fault PatternsSFP24Tainted input to command
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
7 Pernicious Kingdoms
Modifications
Modification DateModifierOrganizationSource
2008-07-01Sean EidemillerCigital
added/updated demonstrative examples
2008-07-01Eric DalciCigital
updated Demonstrative_Example, Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-11-24CWE Content TeamMITRE
updated Description, Other_Notes
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples
2009-10-29CWE Content TeamMITRE
updated Description
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-06-27CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2013-02-21CWE Content TeamMITRE
updated Potential_Mitigations
2014-02-18CWE Content TeamMITRE
updated Related_Attack_Patterns
2014-06-23CWE Content TeamMITRE
updated Demonstrative_Examples, Other_Notes, Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Demonstrative_Examples, Relationships, Taxonomy_Mappings
2017-01-19CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Causal_Nature, Relationships

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Page Last Updated: November 14, 2017