界: Input Validation and Representation

輸入驗證和表示法問題是由中繼字元、替代編碼和數值表示法引起的。信任輸入會導致安全問題。問題包括：「Buffer Overflows」、「Cross-Site Scripting」攻擊、「SQL Injection」及其他許多問題。

Denial of Service: Format String

Java/JSP

Abstract

允許使用者輸入以控制格式參數，可讓攻擊者能夠使系統拋出異常或洩漏資訊。

Explanation

攻擊者也許能夠修改 Format String 引數，使系統拋出異常。如果此異常處於未捕捉到的狀態，則可能使應用程式當機。或者，如果在其他引數中使用了敏感資訊，攻擊者便可能變更 Format String 以擷取此資訊。

範例 1：以下程式碼允許使用者指定 Formatter.format() 的 Format String 引數。


  ...
  Formatter formatter = new Formatter(Locale.US);
  String format = "The customer: %s %s has the balance %4$." + userInput + "f";
  formatter.format(format, firstName, lastName, accountNo, balance);
  ...

此程式的目的是讓使用者指定其顯示餘額的小數點。但事實上，對於這點，並沒有任何限制。如果使用者可指定任何內容，將可能導致異常，例如拋出 java.util.MissingFormatArgumentException，由於這不在 try 區塊中，所以可能導致應用程式失敗。
在此範例中，更嚴重的是，如果攻擊者可指定使用者輸入「2f %3$s %4$.2」，則 Format String 將會是「The customer: %s %s has the balance %4$.2f %3$s %4$.2」。然後，這將會導致敏感的 accountNo 包含到產生的字串中。

References

[1] IDS06-J. Exclude unsanitized user input from format strings CERT

[2] Standards Mapping - Common Weakness Enumeration CWE ID 730

[3] Standards Mapping - DISA Control Correlation Identifier Version 2 CCI-001094, CCI-001310

[4] Standards Mapping - NIST Special Publication 800-53 Revision 4 SC-5 Denial of Service Protection (P1), SI-10 Information Input Validation (P1)

[5] Standards Mapping - NIST Special Publication 800-53 Revision 5 SC-5 Denial of Service Protection, SI-10 Information Input Validation

[6] Standards Mapping - OWASP API 2023 API8 Security Misconfiguration

[7] Standards Mapping - OWASP Mobile 2014 M1 Weak Server Side Controls

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

[9] Standards Mapping - OWASP Mobile Application Security Verification Standard 2.0 MASVS-CODE-4

[10] Standards Mapping - OWASP Top 10 2004 A9 Application Denial of Service

[11] Standards Mapping - OWASP Top 10 2013 A1 Injection

[12] Standards Mapping - OWASP Top 10 2017 A1 Injection

[13] Standards Mapping - OWASP Top 10 2021 A03 Injection

[14] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 Requirement 6.5.9

[15] Standards Mapping - Payment Card Industry Data Security Standard Version 3.0 Requirement 6.5.6

[16] Standards Mapping - Payment Card Industry Data Security Standard Version 3.1 Requirement 6.5.6

[17] Standards Mapping - Payment Card Industry Data Security Standard Version 3.2 Requirement 6.5.6

[18] Standards Mapping - Payment Card Industry Data Security Standard Version 3.2.1 Requirement 6.5.6

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

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

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

[22] 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

[23] 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

[24] Standards Mapping - Security Technical Implementation Guide Version 3.1 APP6080 CAT II

[25] Standards Mapping - Security Technical Implementation Guide Version 3.4 APP6080 CAT II

[26] Standards Mapping - Security Technical Implementation Guide Version 3.5 APP6080 CAT II

[27] Standards Mapping - Security Technical Implementation Guide Version 3.6 APP6080 CAT II

[28] Standards Mapping - Security Technical Implementation Guide Version 3.7 APP6080 CAT II

[29] Standards Mapping - Security Technical Implementation Guide Version 3.9 APP6080 CAT II

[30] Standards Mapping - Security Technical Implementation Guide Version 3.10 APP6080 CAT II

[31] Standards Mapping - Security Technical Implementation Guide Version 4.2 APSC-DV-002400 CAT II

[32] Standards Mapping - Security Technical Implementation Guide Version 4.3 APSC-DV-002400 CAT II

[33] Standards Mapping - Security Technical Implementation Guide Version 4.4 APSC-DV-002400 CAT II

[34] Standards Mapping - Security Technical Implementation Guide Version 4.5 APSC-DV-002400 CAT II

[35] Standards Mapping - Security Technical Implementation Guide Version 4.6 APSC-DV-002400 CAT II

[36] Standards Mapping - Security Technical Implementation Guide Version 4.7 APSC-DV-002400 CAT II

[37] Standards Mapping - Security Technical Implementation Guide Version 4.8 APSC-DV-002400 CAT II

[38] Standards Mapping - Security Technical Implementation Guide Version 4.9 APSC-DV-002400 CAT II

[39] Standards Mapping - Security Technical Implementation Guide Version 4.10 APSC-DV-002400 CAT II

[40] Standards Mapping - Security Technical Implementation Guide Version 4.11 APSC-DV-002400 CAT II

[41] Standards Mapping - Security Technical Implementation Guide Version 4.1 APSC-DV-002400 CAT II

[42] Standards Mapping - Security Technical Implementation Guide Version 5.1 APSC-DV-002400 CAT II

[43] Standards Mapping - Security Technical Implementation Guide Version 5.2 APSC-DV-002400 CAT II

[44] Standards Mapping - Security Technical Implementation Guide Version 5.3 APSC-DV-002400 CAT II, APSC-DV-002530 CAT II

[45] Standards Mapping - Security Technical Implementation Guide Version 6.1 APSC-DV-002400 CAT II, APSC-DV-002530 CAT II

[46] Standards Mapping - Web Application Security Consortium Version 2.00 Denial of Service (WASC-10)

[47] Standards Mapping - Web Application Security Consortium 24 + 2 Denial of Service

desc.dataflow.java.denial_of_service_format_string