名前: Improper Restriction of XML External Entity Reference

The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.

一般情報

背景の詳細

導入モード

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

適用可能なプラットフォーム

言語

クラス： Not Language-Specific (Undetermined)
名前： XML (Undetermined)

テクノロジー

クラス： Not Technology-Specific (Undetermined)
クラス： Web Based (Undetermined)

一般的な結果

スコープ	影響	可能性
Confidentiality	Read Application Data, Read Files or Directories 注記：If the attacker is able to include a crafted DTD and a default entity resolver is enabled, the attacker may be able to access arbitrary files on the system. By submitting an XML file that defines an external entity with a file:// URI, an attacker can cause the processing application to read the contents of a local file. For example, a URI such as "file:///c:/winnt/win.ini" designates (in Windows) the file C:\Winnt\win.ini, or file:///etc/passwd designates the password file in Unix-based systems. Once the content of the URI is read, it is fed back into the application that is processing the XML. This application may echo back the data (e.g., in an error message), thereby exposing the file contents.
Integrity	Bypass Protection Mechanism 注記：An attacker may supply a crafted DTD using URIs with schemes such as http://, forcing the application to make outgoing HTTP requests to servers that the attacker cannot reach directly, which can be used to bypass firewall restrictions; hide the source of attacks such as port scanning; or otherwise leverage the server's trust relationship with other entities.
Availability	DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory) 注記：The product could consume excessive CPU cycles or memory using a URI that points to a large file, or a device that always returns data such as /dev/random. Alternately, the URI could reference a file that contains many nested or recursive entity references to further slow down parsing.

観察された例

参考文献	説明
CVE-2022-42745	Recruiter software allows reading arbitrary files using XXE
CVE-2005-1306	A browser control can allow remote attackers to determine the existence of files via Javascript containing XML script.
CVE-2012-5656	XXE during SVG image conversion
CVE-2012-2239	XXE in PHP application allows reading the application's configuration file.
CVE-2012-3489	XXE in database server
CVE-2012-4399	XXE in rapid web application development framework allows reading arbitrary files.
CVE-2012-3363	XXE via XML-RPC request.
CVE-2012-0037	XXE in office document product using RDF.
CVE-2011-4107	XXE in web-based administration tool for database.
CVE-2010-3322	XXE in product that performs large-scale data analysis.
CVE-2009-1699	XXE in XSL stylesheet functionality in a common library used by some web browsers.

潜在的な緩和策

Phases : Implementation // System Configuration
Many XML parsers and validators can be configured to disable external entity expansion.

検出方法

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.)
有効性 : High

脆弱性マッピングノート

理由 : 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.
コメント : 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.

ノート

CWE-918 (SSRF) and CWE-611 (XXE) are closely related, because they both involve web-related technologies and can launch outbound requests to unexpected destinations. However, XXE can be performed client-side, or in other contexts in which the software is not acting directly as a server, so the "Server" portion of the SSRF acronym does not necessarily apply.

参考文献

REF-496

XML External Entity (XXE) Processing
OWASP.
https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Processing

REF-497

XML External Entity Attacks (XXE)
Sascha Herzog.
https://mohemiv.com/files/XML_Exteral_Entity_Attack.pdf

REF-498

XXE (Xml eXternal Entity) Attack
Gregory Steuck.
https://seclists.org/bugtraq/2002/Oct/420/

REF-1534

Automated Technical Debt Measure, Version 2
OMG.
https://www.omg.org/spec/ATDM2/1.0/PDF

登録情報

名前	組織	日付	リリース日	Version
Anonymous Tool Vendor (under NDA)		2007-05-07 +00:00	2007-05-07 +00:00	Draft 6

変更履歴

名前	組織	日付	コメント
Eric Dalci	Cigital	2008-07-01 +00:00	updated Time_of_Introduction
CWE Content Team	MITRE	2008-09-08 +00:00	updated Description, Relationships, Observed_Example, Other_Notes, Taxonomy_Mappings
CWE Content Team	MITRE	2010-02-16 +00:00	updated Taxonomy_Mappings
CWE Content Team	MITRE	2010-09-27 +00:00	updated Background_Details, Other_Notes
CWE Content Team	MITRE	2011-03-29 +00:00	updated Name
CWE Content Team	MITRE	2011-06-01 +00:00	updated Common_Consequences
CWE Content Team	MITRE	2012-05-11 +00:00	updated Relationships
CWE Content Team	MITRE	2013-02-21 +00:00	updated Alternate_Terms, Applicable_Platforms, Background_Details, Common_Consequences, Description, Name, Observed_Examples, Potential_Mitigations, References, Relationship_Notes, Relationships, Taxonomy_Mappings
CWE Content Team	MITRE	2014-07-30 +00:00	updated Relationships, Taxonomy_Mappings
CWE Content Team	MITRE	2015-12-07 +00:00	updated Relationships
CWE Content Team	MITRE	2017-11-08 +00:00	updated Modes_of_Introduction, References, Relationships, Relevant_Properties
CWE Content Team	MITRE	2018-03-27 +00:00	updated Relationships
CWE Content Team	MITRE	2019-01-03 +00:00	updated Related_Attack_Patterns
CWE Content Team	MITRE	2019-06-20 +00:00	updated Name, Type
CWE Content Team	MITRE	2019-09-19 +00:00	updated Relationships
CWE Content Team	MITRE	2020-02-24 +00:00	updated Applicable_Platforms, Relationships
CWE Content Team	MITRE	2020-08-20 +00:00	updated Relationships
CWE Content Team	MITRE	2020-12-10 +00:00	updated Relationships
CWE Content Team	MITRE	2021-07-20 +00:00	updated Relationships
CWE Content Team	MITRE	2021-10-28 +00:00	updated Relationships
CWE Content Team	MITRE	2022-06-28 +00:00	updated Relationships
CWE Content Team	MITRE	2023-01-31 +00:00	updated Alternate_Terms, Common_Consequences, Description
CWE Content Team	MITRE	2023-04-27 +00:00	updated Detection_Factors, References, Relationships
CWE Content Team	MITRE	2023-06-29 +00:00	updated Mapping_Notes
CWE Content Team	MITRE	2023-10-26 +00:00	updated Observed_Examples
CWE Content Team	MITRE	2025-09-09 +00:00	updated References
CWE Content Team	MITRE	2025-12-11 +00:00	updated Applicable_Platforms, Background_Details, Common_Consequences, Description, Diagram, Relationships, Weakness_Ordinalities
CWE Content Team	MITRE	2026-10-28 +00:00	updated References

CWE-611 詳細

CWE-611