Description

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.

Modes of Introduction:

– Architecture and Design

Related Weaknesses

CWE-657
CWE-693

Consequences

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.

Potential Mitigations

Phase: Architecture and Design

Description: 

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).

Phase: Architecture and Design

Description: 

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

CVE References