界: Input Validation and Representation

输入验证与表示问题是由元字符、交替编码和数字表示引起的。安全问题源于信任输入。这些问题包括：“Buffer Overflows”、“Cross-Site Scripting”攻击、“SQL Injection”等其他问题。

Insecure Sanitizer Policy

Java/JSP

Abstract

使用用户控制或不可信赖的数据来定义 HTML sanitizer 策略可能会允许攻击者避开清除要求并发起 cross-site scripting (XSS) 攻击。

Explanation

概括性术语“输入处理”描述了输入数据的验证、清除、筛选和编码/解码等功能。Cross-site scripting、SQL injection 和 process control 漏洞是由于输入处理不正确或者缺少输入处理造成的。除了输入验证之外，通常还会实现输入的清除，它会将输入转换为可接受的形式。HTML 清除是指清理和擦除用户输入，以便仅允许那些被视为安全的标签、属性和元素。
实施彻底的 HTML 清除策略十分困难；成功实施的关键是了解使用数据的上下文。每个上下文都有其各自的漏洞，应具体情况具体分析。使用 HTML sanitizer（例如 OWASP HTML sanitizer）防止 Web 应用程序中出现 XSS 漏洞是明智的，但实施不当会导致虚假安全。
示例 1：以下 Java 代码使用用户控制的输入变量 elements 构建 HTML sanitizer 策略：


...
String elements = prop.getProperty("AllowedElements");
...
public static final PolicyFactory POLICY_DEFINITION = new HtmlPolicyBuilder()
															.allowElements(elements)
															.toFactory();

....

恶意用户可能会通过将危险元素（如 <script>）提供给 elements 而使 HTML sanitizer 策略接受这些元素。

References

[1] OWASP Cross-Site Scripting (XSS) Prevention Cheat Sheet

[2] Understanding Malicious Content Mitigation for Web Developers CERT

[3] HTML 4.01 Specification W3

[4] Standards Mapping - Common Weakness Enumeration CWE ID 79, CWE ID 80

[5] Standards Mapping - Common Weakness Enumeration Top 25 2019 [2] CWE ID 079

[6] Standards Mapping - Common Weakness Enumeration Top 25 2020 [1] CWE ID 079

[7] Standards Mapping - Common Weakness Enumeration Top 25 2021 [2] CWE ID 079

[8] Standards Mapping - Common Weakness Enumeration Top 25 2022 [2] CWE ID 079

[9] Standards Mapping - Common Weakness Enumeration Top 25 2023 [2] CWE ID 079

[10] Standards Mapping - Common Weakness Enumeration Top 25 2024 [1] CWE ID 079

[11] Standards Mapping - DISA Control Correlation Identifier Version 2 CCI-001310

[12] Standards Mapping - FIPS200 SI

[13] Standards Mapping - General Data Protection Regulation (GDPR) Insufficient Data Protection

[14] Standards Mapping - NIST Special Publication 800-53 Revision 4 SI-10 Information Input Validation (P1), SI-15 Information Output Filtering (P0)

[15] Standards Mapping - NIST Special Publication 800-53 Revision 5 SI-10 Information Input Validation, SI-15 Information Output Filtering

[16] Standards Mapping - OWASP Application Security Verification Standard 4.0 5.3.3 Output Encoding and Injection Prevention Requirements (L1 L2 L3), 5.3.6 Output Encoding and Injection Prevention Requirements (L1 L2 L3)

[17] Standards Mapping - OWASP Mobile 2014 M7 Client Side Injection

[18] Standards Mapping - OWASP Mobile 2024 M4 Insufficient Input/Output Validation

[19] Standards Mapping - OWASP Top 10 2004 A4 Cross Site Scripting

[20] Standards Mapping - OWASP Top 10 2007 A1 Cross Site Scripting (XSS)

[21] Standards Mapping - OWASP Top 10 2010 A2 Cross-Site Scripting (XSS)

[22] Standards Mapping - OWASP Top 10 2013 A5 Security Misconfiguration

[23] Standards Mapping - OWASP Top 10 2017 A6 Security Misconfiguration

[24] Standards Mapping - OWASP Top 10 2021 A05 Security Misconfiguration

[25] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 Requirement 6.5.4

[26] Standards Mapping - Payment Card Industry Data Security Standard Version 1.2 Requirement 6.3.1.1, Requirement 6.5.1

[27] Standards Mapping - Payment Card Industry Data Security Standard Version 2.0 Requirement 6.5.7

[28] Standards Mapping - Payment Card Industry Data Security Standard Version 3.0 Requirement 6.5.7

[29] Standards Mapping - Payment Card Industry Data Security Standard Version 3.1 Requirement 6.5.7

[30] Standards Mapping - Payment Card Industry Data Security Standard Version 3.2 Requirement 6.5.7

[31] Standards Mapping - Payment Card Industry Data Security Standard Version 3.2.1 Requirement 6.5.7

[32] Standards Mapping - Payment Card Industry Data Security Standard Version 4.0 Requirement 6.2.4

[33] Standards Mapping - Payment Card Industry Data Security Standard Version 4.0.1 Requirement 6.2.4

[34] Standards Mapping - Payment Card Industry Software Security Framework 1.0 Control Objective 4.2 - Critical Asset Protection

[35] Standards Mapping - Payment Card Industry Software Security Framework 1.1 Control Objective 4.2 - Critical Asset Protection, Control Objective B.3.1 - Terminal Software Attack Mitigation, Control Objective B.3.1.1 - Terminal Software Attack Mitigation

[36] Standards Mapping - Payment Card Industry Software Security Framework 1.2 Control Objective 4.2 - Critical Asset Protection, Control Objective B.3.1 - Terminal Software Attack Mitigation, Control Objective B.3.1.1 - Terminal Software Attack Mitigation, Control Objective C.3.2 - Web Software Attack Mitigation

[37] Standards Mapping - SANS Top 25 2009 Insecure Interaction - CWE ID 079

[38] Standards Mapping - SANS Top 25 2010 Insecure Interaction - CWE ID 079

[39] Standards Mapping - SANS Top 25 2011 Insecure Interaction - CWE ID 079

[40] Standards Mapping - Security Technical Implementation Guide Version 3.1 APP3510 CAT I, APP3580 CAT I

[41] Standards Mapping - Security Technical Implementation Guide Version 3.4 APP3510 CAT I, APP3580 CAT I

[42] Standards Mapping - Security Technical Implementation Guide Version 3.5 APP3510 CAT I, APP3580 CAT I

[43] Standards Mapping - Security Technical Implementation Guide Version 3.6 APP3510 CAT I, APP3580 CAT I

[44] Standards Mapping - Security Technical Implementation Guide Version 3.7 APP3510 CAT I, APP3580 CAT I

[45] Standards Mapping - Security Technical Implementation Guide Version 3.9 APP3510 CAT I, APP3580 CAT I

[46] Standards Mapping - Security Technical Implementation Guide Version 3.10 APP3510 CAT I, APP3580 CAT I

[47] Standards Mapping - Security Technical Implementation Guide Version 5.3 APSC-DV-002530 CAT II

[48] Standards Mapping - Security Technical Implementation Guide Version 6.1 APSC-DV-002530 CAT II

[49] Standards Mapping - Web Application Security Consortium Version 2.00 Cross-Site Scripting (WASC-08)

[50] Standards Mapping - Web Application Security Consortium 24 + 2 Cross-Site Scripting

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