CWE

Reliance on a Single Factor in a Security Decision

ID: 654		Date: (C)2012-05-14   (M)2022-10-10
Type: weakness		Status: DRAFT
Abstraction Type: Base

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.

Applicable Platforms
Language Class: All

Time Of Introduction

• Architecture and Design
• Implementation
• Operation

Related Attack Patterns

• CAPEC-274

Common Consequences

Scope	Technical Impact	Notes
Access_Control	Gain privileges / 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.

Detection Methods
None

Potential Mitigations

Phase	Strategy	Description	Effectiveness	Notes
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).
		Use redundant access rules on different choke points (e.g., firewalls).

Relationships

Related CWE	Type	View	Chain
CWE-654 ChildOf CWE-907	Category	CWE-888

Demonstrative Examples   (Details)

1. Password-only authentication is perhaps the most well-known example of use of a single factor. Anybody who knows a user's password can impersonate that user.
2. When authenticating, use multiple factors, such as "something you know" (such as a password) and "something you have" (such as a hardware-based one-time password generator, or a biometric device).

White Box Definitions
None

Black Box Definitions
None

Taxynomy Mappings
None

References:

1. Jerome H. Saltzer Michael D. Schroeder .The Protection of Information in Computer Systems. Proceedings of the IEEE 63. Published on September, 1975.
2. Sean Barnum Michael Gegick .Separation of Privilege. Published on 2005-12-06.