名前: Dynamic Variable Evaluation

In a language where the user can influence the name of a variable at runtime, if the variable names are not controlled, an attacker can read or write to arbitrary variables, or access arbitrary functions.

一般情報

背景の詳細

導入モード

Implementation

適用可能なプラットフォーム

言語

名前： PHP (Undetermined)
名前： Perl (Undetermined)

一般的な結果

スコープ	影響	可能性
Confidentiality Integrity Availability	Modify Application Data, Execute Unauthorized Code or Commands, Varies by Context 注記：An attacker could gain unauthorized read or write access to internal program variables and possibly execute arbitrary code. The resultant vulnerabilities depend on the behavior of the application, both at the crossover point and in any control/data flow that is reachable by the related variables or functions.

観察された例

参考文献	説明
CVE-2009-0422	Chain: Dynamic variable evaluation allows resultant remote file inclusion and path traversal.
CVE-2007-2431	Chain: dynamic variable evaluation in PHP program used to modify critical, unexpected $_SERVER variable for resultant XSS.
CVE-2006-4904	Chain: dynamic variable evaluation in PHP program used to conduct remote file inclusion.
CVE-2006-4019	Dynamic variable evaluation in mail program allows reading and modifying attachments and preferences of other users.

潜在的な緩和策

Phases : Implementation
Refactor the code to avoid dynamic variable evaluation whenever possible.
Phases : Implementation
Use only allowlists of acceptable variable or function names.
Phases : Implementation
For function names, ensure that you are only calling functions that accept the proper number of arguments, to avoid unexpected null arguments.

脆弱性マッピングノート

理由 : This CWE entry is at the Variant 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

Under-studied, probably under-reported. Few researchers look for this issue; most public reports are for PHP, although other languages are affected. This issue is likely to grow in PHP as developers begin to implement functionality in place of register_globals.

参考文献

REF-517

Dynamic Evaluation Vulnerabilities in PHP applications
Steve Christey.
https://seclists.org/fulldisclosure/2006/May/35

REF-518

A Study In Scarlet: Exploiting Common Vulnerabilities in PHP Applications
Shaun Clowes.
https://securereality.com.au/study-in-scarlett/

登録情報

名前	組織	日付	リリース日	Version
CWE Content Team	MITRE	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 Applicable_Platforms, Relationships
CWE Content Team	MITRE	2008-10-14 +00:00	updated Background_Details, Description
CWE Content Team	MITRE	2011-03-29 +00:00	updated Description
CWE Content Team	MITRE	2011-06-01 +00:00	updated Common_Consequences
CWE Content Team	MITRE	2012-05-11 +00:00	updated Common_Consequences, Relationships
CWE Content Team	MITRE	2012-10-30 +00:00	updated Potential_Mitigations
CWE Content Team	MITRE	2013-02-21 +00:00	updated Common_Consequences, Observed_Examples, Potential_Mitigations, Relationships, Weakness_Ordinalities
CWE Content Team	MITRE	2014-07-30 +00:00	updated Relationships
CWE Content Team	MITRE	2017-11-08 +00:00	updated References
CWE Content Team	MITRE	2020-02-24 +00:00	updated Relationships
CWE Content Team	MITRE	2020-06-25 +00:00	updated Potential_Mitigations
CWE Content Team	MITRE	2023-04-27 +00:00	updated References, Relationships, Type
CWE Content Team	MITRE	2023-06-29 +00:00	updated Mapping_Notes
CWE Content Team	MITRE	2026-10-28 +00:00	updated Common_Consequences, Description

CWE-627 詳細

CWE-627