Reino: Security Features

La seguridad de un software no es un software de seguridad. Nos preocupamos de cuestiones como la autenticación, el control de acceso, la confidencialidad, la criptografía y la gestión de privilegios.

Key Management: Empty HMAC Key

Abstract

Las claves de HMAC vacías pueden poner en riesgo la seguridad del sistema de una forma que no es fácil de resolver.

Explanation

Nunca es una buena idea utilizar una clave HMAC vacía. La intensidad criptográfica de HMAC depende del tamaño de la clave secreta, que se utiliza para calcular y verificar los valores de autenticación de mensajes. El uso de una clave vacía debilita la intensidad criptográfica de la función HMAC.
Ejemplo 1: El siguiente código utiliza una clave vacía para el cálculo de HMAC:


...
DATA: lo_hmac TYPE Ref To cl_abap_hmac,
             Input_string type string.

CALL METHOD cl_abap_hmac=>get_instance
  EXPORTING
    if_algorithm = 'SHA3'
    if_key       = space
  RECEIVING
    ro_object    = lo_hmac.

" update HMAC with input
lo_hmac->update( if_data = input_string ).

" finalise hmac
lo_digest->final( ).

...

Puede ser que el código mostrado en el Example 1 se ejecute correctamente, pero cualquiera con acceso a él puede darse cuenta de que utiliza una clave HMAC vacía. Una vez que se haya distribuido el programa, no hay forma de cambiar la clave HMAC vacía, a menos que el programa tenga instaladas las revisiones. Un empleado malintencionado con acceso a esta información puede utilizarla para comprometer la función HMAC. Además, el código en el Example 1 es vulnerable a las falsificaciones y a los ataques de recuperación de claves.

References

[1] RFC 2104 - HMAC: Keyed-Hashing for Message Authentication Internet Engineering Task Force (IETF)

[2] New Results on NMAC/HMAC when Instantiated with Popular Hash Functions Journal of Universal Computer Science (J.UCS)

[3] Standards Mapping - Common Weakness Enumeration CWE ID 321

[4] Standards Mapping - Common Weakness Enumeration Top 25 2019 [13] CWE ID 287, [19] CWE ID 798

[5] Standards Mapping - Common Weakness Enumeration Top 25 2020 [14] CWE ID 287, [20] CWE ID 798

[6] Standards Mapping - Common Weakness Enumeration Top 25 2021 [14] CWE ID 287, [16] CWE ID 798

[7] Standards Mapping - Common Weakness Enumeration Top 25 2022 [14] CWE ID 287, [15] CWE ID 798

[8] Standards Mapping - Common Weakness Enumeration Top 25 2023 [13] CWE ID 287, [18] CWE ID 798

[9] Standards Mapping - DISA Control Correlation Identifier Version 2 CCI-002450

[10] Standards Mapping - FIPS200 IA

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

[12] Standards Mapping - NIST Special Publication 800-53 Revision 4 SC-12 Cryptographic Key Establishment and Management (P1), SC-13 Cryptographic Protection (P1)

[13] Standards Mapping - NIST Special Publication 800-53 Revision 5 SC-12 Cryptographic Key Establishment and Management, SC-13 Cryptographic Protection

[14] Standards Mapping - OWASP Application Security Verification Standard 4.0 2.6.3 Look-up Secret Verifier Requirements (L2 L3), 2.7.1 Out of Band Verifier Requirements (L1 L2 L3), 2.7.2 Out of Band Verifier Requirements (L1 L2 L3), 2.7.3 Out of Band Verifier Requirements (L1 L2 L3), 2.8.4 Single or Multi Factor One Time Verifier Requirements (L2 L3), 2.8.5 Single or Multi Factor One Time Verifier Requirements (L2 L3), 2.9.1 Cryptographic Software and Devices Verifier Requirements (L2 L3), 2.10.2 Service Authentication Requirements (L2 L3), 2.10.4 Service Authentication Requirements (L2 L3), 3.5.2 Token-based Session Management (L2 L3), 3.7.1 Defenses Against Session Management Exploits (L1 L2 L3), 6.2.1 Algorithms (L1 L2 L3), 6.4.1 Secret Management (L2 L3), 6.4.2 Secret Management (L2 L3), 9.2.3 Server Communications Security Requirements (L2 L3), 10.2.3 Malicious Code Search (L3)

[15] Standards Mapping - OWASP Mobile 2014 M6 Broken Cryptography

[16] Standards Mapping - OWASP Mobile 2024 M10 Insufficient Cryptography

[17] Standards Mapping - OWASP Mobile Application Security Verification Standard 2.0 MASVS-CRYPTO-2

[18] Standards Mapping - OWASP Top 10 2004 A8 Insecure Storage

[19] Standards Mapping - OWASP Top 10 2007 A8 Insecure Cryptographic Storage

[20] Standards Mapping - OWASP Top 10 2010 A7 Insecure Cryptographic Storage

[21] Standards Mapping - OWASP Top 10 2013 A6 Sensitive Data Exposure

[22] Standards Mapping - OWASP Top 10 2017 A3 Sensitive Data Exposure

[23] Standards Mapping - OWASP Top 10 2021 A02 Cryptographic Failures

[24] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 Requirement 6.5.8, Requirement 8.4

[25] Standards Mapping - Payment Card Industry Data Security Standard Version 1.2 Requirement 6.3.1.3, Requirement 6.5.8, Requirement 8.4

[26] Standards Mapping - Payment Card Industry Data Security Standard Version 2.0 Requirement 6.3.1, Requirement 6.5.3, Requirement 8.4

[27] Standards Mapping - Payment Card Industry Data Security Standard Version 3.0 Requirement 6.3.1, Requirement 6.5.3, Requirement 8.2.1

[28] Standards Mapping - Payment Card Industry Data Security Standard Version 3.1 Requirement 6.3.1, Requirement 6.5.3, Requirement 8.2.1

[29] Standards Mapping - Payment Card Industry Data Security Standard Version 3.2 Requirement 6.3.1, Requirement 6.5.3, Requirement 8.2.1

[30] Standards Mapping - Payment Card Industry Data Security Standard Version 3.2.1 Requirement 6.3.1, Requirement 6.5.3, Requirement 8.2.1

[31] Standards Mapping - Payment Card Industry Data Security Standard Version 4.0 Requirement 6.2.4, Requirement 6.5.3, Requirement 6.5.6, Requirement 8.3.2

[32] Standards Mapping - Payment Card Industry Software Security Framework 1.0 Control Objective 7.2 - Use of Cryptography

[33] Standards Mapping - Payment Card Industry Software Security Framework 1.1 Control Objective 7.2 - Use of Cryptography, Control Objective B.2.3 - Terminal Software Design

[34] Standards Mapping - Payment Card Industry Software Security Framework 1.2 Control Objective 7.2 - Use of Cryptography, Control Objective B.2.3 - Terminal Software Design

[35] Standards Mapping - SANS Top 25 2009 Porous Defenses - CWE ID 259

[36] Standards Mapping - Security Technical Implementation Guide Version 3.1 APP3210.1 CAT II, APP3350 CAT I

[37] Standards Mapping - Security Technical Implementation Guide Version 3.4 APP3210.1 CAT II, APP3350 CAT I

[38] Standards Mapping - Security Technical Implementation Guide Version 3.5 APP3210.1 CAT II, APP3350 CAT I

[39] Standards Mapping - Security Technical Implementation Guide Version 3.6 APP3210.1 CAT II, APP3350 CAT I

[40] Standards Mapping - Security Technical Implementation Guide Version 3.7 APP3210.1 CAT II, APP3350 CAT I

[41] Standards Mapping - Security Technical Implementation Guide Version 3.9 APP3210.1 CAT II, APP3350 CAT I

[42] Standards Mapping - Security Technical Implementation Guide Version 3.10 APP3210.1 CAT II, APP3350 CAT I

[43] Standards Mapping - Security Technical Implementation Guide Version 4.2 APSC-DV-002010 CAT II

[44] Standards Mapping - Security Technical Implementation Guide Version 4.3 APSC-DV-002010 CAT II

[45] Standards Mapping - Security Technical Implementation Guide Version 4.4 APSC-DV-002010 CAT II

[46] Standards Mapping - Security Technical Implementation Guide Version 4.5 APSC-DV-002010 CAT II

[47] Standards Mapping - Security Technical Implementation Guide Version 4.6 APSC-DV-002010 CAT II

[48] Standards Mapping - Security Technical Implementation Guide Version 4.7 APSC-DV-002010 CAT II

[49] Standards Mapping - Security Technical Implementation Guide Version 4.8 APSC-DV-002010 CAT II

[50] Standards Mapping - Security Technical Implementation Guide Version 4.9 APSC-DV-002010 CAT II

[51] Standards Mapping - Security Technical Implementation Guide Version 4.10 APSC-DV-002010 CAT II

[52] Standards Mapping - Security Technical Implementation Guide Version 4.11 APSC-DV-002010 CAT II

[53] Standards Mapping - Security Technical Implementation Guide Version 4.1 APSC-DV-002010 CAT II

[54] Standards Mapping - Security Technical Implementation Guide Version 5.1 APSC-DV-002010 CAT II

[55] Standards Mapping - Security Technical Implementation Guide Version 5.2 APSC-DV-002010 CAT II

[56] Standards Mapping - Security Technical Implementation Guide Version 5.3 APSC-DV-002010 CAT II

[57] Standards Mapping - Web Application Security Consortium Version 2.00 Information Leakage (WASC-13)

desc.structural.abap.key_management_empty_hmac_key

Abstract

Las claves de HMAC vacías pueden poner en riesgo la seguridad del sistema de una forma que no es fácil de resolver.

Explanation


...
using (HMAC hmac = HMAC.Create("HMACSHA512"))
{
  string hmacKey = "";
  byte[] keyBytes = Encoding.ASCII.GetBytes(hmacKey);
  hmac.Key = keyBytes;
  ...
}
...

Puede ser que el código del Example 1 se ejecute correctamente, pero cualquiera con acceso a él puede darse cuenta de que utiliza una clave HMAC vacía. Una vez que se haya distribuido el programa, no hay forma de cambiar la clave HMAC vacía, a menos que el programa tenga instaladas las revisiones. Un empleado malintencionado con acceso a esta información puede utilizarla para comprometer la función HMAC. Además, el código en el Example 1 es vulnerable a las falsificaciones y a los ataques de recuperación de claves.