CWE

Key Exchange without Entity Authentication

ID: 322		Date: (C)2012-05-14   (M)2022-10-10
Type: weakness		Status: DRAFT
Abstraction Type: Base

Description

The software performs a key exchange with an actor without verifying the identity of that actor.

Extended Description

Performing a key exchange will preserve the integrity of the information sent between two entities, but this will not guarantee that the entities are who they claim they are. This may enable a set of "man-in-the-middle" attacks. Typically, this involves a victim client that contacts a malicious server that is impersonating a trusted server. If the client skips authentication or ignores an authentication failure, the malicious server may request authentication information from the user. The malicious server can then use this authentication information to log in to the trusted server using the victim's credentials, sniff traffic between the victim and trusted server, etc.

Likelihood of Exploit: High

Applicable Platforms
Language Class: All

Time Of Introduction

• Architecture and Design

Common Consequences

Scope	Technical Impact	Notes
Access_Control	Bypass protection mechanism	No authentication takes place in this process, bypassing an assumed protection of encryption.
Confidentiality	Read application data	The encrypted communication between a user and a trusted host may be subject to a "man-in-the-middle" sniffing attack.

Detection Methods
None

Potential Mitigations

Phase	Strategy	Description	Effectiveness	Notes
Architecture and Design		Ensure that proper authentication is included in the system design.
Implementation		Understand and properly implement all checks necessary to ensure the identity of entities involved in encrypted communications.

Relationships

Related CWE	Type	View	Chain
CWE-322 ChildOf CWE-903	Category	CWE-888

Demonstrative Examples   (Details)

1. Many systems have used Diffie-Hellman key exchange without authenticating the entities exchanging keys, leading to man-in-the-middle attacks. Many people using SSL/TLS skip the authentication (often unknowingly).

White Box Definitions
None

Black Box Definitions
None

Taxynomy Mappings

Taxynomy	Id	Name	Fit
CLASP		Key exchange without entity authentication

References:

1. Michael Howard David LeBlanc John Viega .24 Deadly Sins of Software Security. McGraw-Hill. Section:'"Sin 23: Improper Use of PKI, Especially SSL." Page 347'. Published on 2010.
2. Mark Dowd John McDonald Justin Schuh .The Art of Software Security Assessment 1st Edition. Addison Wesley. Section:'Chapter 2, "Untrustworthy Credentials", Page 37.'. Published on 2006.