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.

Primary

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.

Architecture and Design

Implementation

Operation

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.

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).

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.

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).

CVE-2022-35248
Chat application skips validation when Central Authentication Service
(CAS) is enabled, effectively removing the second factor from
two-factor authentication
https://www.cve.org/CVERecord?id=CVE-2022-35248

Part 4-1
Req SD-3

Part 4-1
Req SD-4

Part 4-1
Req SI-1

Allowed
This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

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.

Pascal Meunier
Purdue University
2008-01-18
Draft 8
2008-01-30

Eric Dalci
Cigital
2008-07-01
updated Time_of_Introduction

CWE Content Team
MITRE
2008-09-08
updated Alternate_Terms, Common_Consequences, Relationships, Other_Notes, Weakness_Ordinalities

CWE Content Team
MITRE
2009-01-12
updated Description, Name

CWE Content Team
MITRE
2009-05-27
updated Relationships

CWE Content Team
MITRE
2010-04-05
updated Related_Attack_Patterns

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences, Maintenance_Notes, Other_Notes

CWE Content Team
MITRE
2012-05-11
updated Relationships

CWE Content Team
MITRE
2012-10-30
updated Potential_Mitigations

CWE Content Team
MITRE
2013-02-21
updated Potential_Mitigations

CWE Content Team
MITRE
2014-07-30
updated Relationships

CWE Content Team
MITRE
2017-11-08
updated Applicable_Platforms, Causal_Nature

CWE Content Team
MITRE
2020-02-24
updated Relationships

CWE Content Team
MITRE
2020-08-20
updated Related_Attack_Patterns

CWE Content Team
MITRE
2020-12-10
updated Relationships

CWE Content Team
MITRE
2021-03-15
updated Alternate_Terms, Maintenance_Notes

CWE Content Team
MITRE
2022-10-13
updated References

CWE Content Team
MITRE
2023-04-27
updated References, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2023-10-26
updated Observed_Examples

"Mapping CWE to 62443" Sub-Working Group
CWE-CAPEC ICS/OT SIG
2023-04-25
Suggested mappings to ISA/IEC 62443.

Design Principle Violation: Reliance on a Single Factor in a Security Decision