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Missing Authentication for Critical Function

ID: 306Date: (C)2012-05-14   (M)2019-01-08
Type: weaknessStatus: DRAFT
Abstraction Type: Variant


The software does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

Likelihood of Exploit: Medium to High

Applicable Platforms
Language Class: Language-independent

Time Of Introduction

  • Architecture and Design

Related Attack Patterns

Common Consequences

ScopeTechnical ImpactNotes
Gain privileges / assume identity
Exposing critical functionality essentially provides an attacker with the privilege level of that functionality. The consequences will depend on the associated functionality, but they can range from reading or modifying sensitive data, access to administrative or other privileged functionality, or possibly even execution of arbitrary code.

Detection Methods

Manual Analysis
This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.
Specifically, manual static analysis is useful for evaluating the correctness of custom authentication mechanisms.
Automated Static Analysis
Automated static analysis is useful for detecting commonly-used idioms for authentication. A tool may be able to analyze related configuration files, such as .htaccess in Apache web servers, or detect the usage of commonly-used authentication libraries.
Generally, automated static analysis tools have difficulty detecting custom authentication schemes. In addition, the software's design may include some functionality that is accessible to any user and does not require an established identity; an automated technique that detects the absence of authentication may report false positives.

Potential Mitigations

Architecture and Design
 Divide the software into anonymous, normal, privileged, and administrative areas. Identify which of these areas require a proven user identity, and use a centralized authentication capability.
Identify all potential communication channels, or other means of interaction with the software, to ensure that all channels are appropriately protected. Developers sometimes perform authentication at the primary channel, but open up a secondary channel that is assumed to be private. For example, a login mechanism may be listening on one network port, but after successful authentication, it may open up a second port where it waits for the connection, but avoids authentication because it assumes that only the authenticated party will connect to the port.
In general, if the software or protocol allows a single session or user state to persist across multiple connections or channels, authentication and appropriate credential management need to be used throughout.
Architecture and Design
 For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Architecture and Design
 Where possible, avoid implementing custom authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment. These may make it easier to provide a clear separation between authentication tasks and authorization tasks.
In environments such as the World Wide Web, the line between authentication and authorization is sometimes blurred. If custom authentication routines are required instead of those provided by the server, then these routines must be applied to every single page, since these pages could be requested directly.
Architecture and Design
Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator [R.306.3].

This is separate from "bypass" issues in which authentication exists, but is faulty.

Related CWETypeViewChain
CWE-306 ChildOf CWE-898 Category CWE-888  

Demonstrative Examples   (Details)

  1. In the following Java example the method createBankAccount is used to create a BankAccount object for a bank management application.

Observed Examples

  1. CVE-2002-1810 : MFV. Access TFTP server without authentication and obtain configuration file with sensitive plaintext information.
  2. CVE-2008-6827 : Agent software running at privileges does not authenticate incoming requests over an unprotected channel, allowing a Shatter" attack.
  3. CVE-2004-0213 : Product enforces restrictions through a GUI but not through privileged APIs.

For more examples, refer to CVE relations in the bottom box.

White Box Definitions

Black Box Definitions

Taxynomy Mappings

PLOVER  No Authentication for Critical Function


  1. Mark Dowd John McDonald Justin Schuh .The Art of Software Security Assessment 1st Edition. Addison Wesley. Section:'Chapter 2, "Common Vulnerabilities of Authentication," Page 36'. Published on 2006.
  2. Frank Kim .Top 25 Series - Rank 19 - Missing Authentication for Critical Function. SANS Software Security Institute. 2010-02-23.
  3. OWASP .OWASP Enterprise Security API (ESAPI) Project.

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