Improper Following of a Certificate's Chain of Trust

Opis

The product does not follow, or incorrectly follows, the chain of trust for a certificate back to a trusted root certificate.

There are several ways in which the chain of trust might be broken, including but not limited to:

- Any certificate in the chain is self-signed, unless it is the root.

- Not every intermediate certificate is checked, starting from the original certificate all the way up to the root certificate.

- An intermediate, CA-signed certificate does not have the expected Basic Constraints or other important extensions.

- The root certificate has been compromised or authorized to the wrong party.

Skutki

• Non-Repudiation

  Hide Activities

  Exploitation of this flaw can lead to the trust of data that may have originated with a spoofed source.

• Integrity, Confidentiality, Availability, Access Control

  Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands

  Data, requests, or actions taken by the attacking entity can be carried out as a spoofed benign entity.

Zapobieganie

• Architecture and Design

  Ensure that proper certificate checking is included in the system design.

• Implementation

  Understand, and properly implement all checks necessary to ensure the integrity of certificate trust integrity.

• Implementation

  If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the full chain of trust.

Przykłady podatności

• CVE-2016-2402 Server allows bypass of certificate pinning by sending a chain of trust that includes a trusted CA that is not pinned.
• CVE-2008-4989 Verification function trusts certificate chains in which the last certificate is self-signed.
• CVE-2012-5821 Chain: Web browser uses a TLS-related function incorrectly, preventing it from verifying that a server's certificate is signed by a trusted certification authority (CA).
• CVE-2009-3046 Web browser does not check if any intermediate certificates are revoked.
• CVE-2009-0265 chain: DNS server does not correctly check return value from the OpenSSL EVP_VerifyFinal function allows bypass of validation of the certificate chain.
• CVE-2009-0124 chain: incorrect check of return value from the OpenSSL EVP_VerifyFinal function allows bypass of validation of the certificate chain.
• CVE-2002-0970 File-transfer software does not validate Basic Constraints of an intermediate CA-signed certificate.
• CVE-2002-0862 Cryptographic API, as used in web browsers, mail clients, and other software, does not properly validate Basic Constraints.

Słabość nadrzędna

• CWE-295 Improper Certificate Validation
• CWE-573 Improper Following of Specification by Caller

Kiedy powstaje

• Implementation — When the product uses certificate pinning, the developer might not properly validate all relevant components of the certificate before pinning the certificate. This can make it difficult or expensive to test after the pinning is complete.
• Implementation — REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Dotyczy

Not Language-Specific, Not Technology-Specific, Web Based

Źródła

1. The CLASP Application Security Process — Secure Software, Inc., 2005
2. The Most Dangerous Code in the World: Validating SSL Certificates in Non-Browser Software — Martin Georgiev, Subodh Iyengar, Suman Jana, Rishita Anubhai, Dan Boneh, Vitaly Shmatikov, 2012
3. 24 Deadly Sins of Software Security — Michael Howard, David LeBlanc, John Viega, "Sin 23: Improper Use of PKI, Especially SSL." Page 347, McGraw-Hill, 2010