Reliance on a Single Factor in a Security Decision

Opis

A protection mechanism relies exclusively, or to a large extent, on the evaluation of a single condition or the integrity of a single object or entity in order to make a decision about granting access to restricted resources or functionality.

Inne nazwy

Separation of Privilege

Some people and publications use the term "Separation of Privilege" to describe this weakness, but this term has dual meanings in current usage. While this entry is closely associated with the original definition of "Separation of Privilege" by Saltzer and Schroeder, others use the same term to describe poor compartmentalization (CWE-653). Because there are multiple interpretations, use of the "Separation of Privilege" term is discouraged.

Skutki

• Access Control

  Gain Privileges or Assume Identity

  If the single factor is compromised (e.g. by theft or spoofing), then the integrity of the entire security mechanism can be violated with respect to the user that is identified by that factor.

• Non-Repudiation

  Hide Activities

  It can become difficult or impossible for the product to be able to distinguish between legitimate activities by the entity who provided the factor, versus illegitimate activities by an attacker.

Zapobieganie

• Architecture and Design

  Use multiple simultaneous checks before granting access to critical operations or granting critical privileges. A weaker but helpful mitigation is to use several successive checks (multiple layers of security).

• Architecture and Design

  Use redundant access rules on different choke points (e.g., firewalls).

Przykłady podatności

• CVE-2022-35248 Chat application skips validation when Central Authentication Service (CAS) is enabled, effectively removing the second factor from two-factor authentication

Słabość nadrzędna

• CWE-657 Violation of Secure Design Principles
• CWE-693 Protection Mechanism Failure

Słabości podrzędne

• CWE-308 Use of Single-factor Authentication
• CWE-309 Use of Password System for Primary Authentication

Kiedy powstaje

• Architecture and Design
• Implementation
• Operation

Dotyczy

Not Language-Specific

Uwagi

This entry is closely associated with the term "Separation of Privilege." This term is used in several different ways in the industry, but they generally combine two closely related principles: compartmentalization (CWE-653) and using only one factor in a security decision (this entry). Proper compartmentalization implicitly introduces multiple factors into a security decision, but there can be cases in which multiple factors are required for authentication or other mechanisms that do not involve compartmentalization, such as performing all required checks on a submitted certificate. It is likely that CWE-653 and CWE-654 will provoke further discussion.

Źródła

1. The Protection of Information in Computer Systems — Jerome H. Saltzer, Michael D. Schroeder, Proceedings of the IEEE 63, 1975
2. Separation of Privilege — Sean Barnum, Michael Gegick, 2005