CWE-1236 詳細

The product saves user-provided information into a Comma-Separated Value (CSV) file, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as a command when the file is opened by a spreadsheet product.

背景の詳細

導入モード

Implementation : The weakness is in the implementation of a software's CSV export feature, in particular how it formats formula entries as the output gets flattened into a text file.

適用可能なプラットフォーム

言語

クラス： Not Language-Specific (Undetermined)

オペレーティングシステム

クラス： Not OS-Specific (Undetermined)

アーキテクチャ

クラス： Not Architecture-Specific (Undetermined)

テクノロジー

名前： Other (Undetermined)

一般的な結果

観察された例

潜在的な緩和策

Phases : Implementation
When generating CSV output, ensure that formula-sensitive metacharacters are effectively escaped or removed from all data before storage in the resultant CSV. Risky characters include '=' (equal), '+' (plus), '-' (minus), and '@' (at).
Phases : Implementation
If a field starts with a formula character, prepend it with a ' (single apostrophe), which prevents Excel from executing the formula.
Phases : Architecture and Design
Certain implementations of spreadsheet software might disallow formulas from executing if the file is untrusted, or if the file is not authored by the current user.

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.

参考文献

REF-21

CSV Injection
OWASP.
https://owasp.org/www-community/attacks/CSV_Injection

REF-22

Data Extraction to Command Execution CSV Injection
Jamie Rougvie.
https://www.veracode.com/blog/secure-development/data-extraction-command-execution-csv-injection

REF-23

The Absurdly Underestimated Dangers of CSV Injection
George Mauer.
https://georgemauer.net/2017/10/07/csv-injection.html

REF-24

Comma Separated Vulnerabilities
James Kettle.
https://rstforums.com/forum/topic/82690-comma-separated-vulnerabilities/

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