Missing Authentication for Critical Function

Description

This vulnerability occurs when a software feature that performs a sensitive action or uses significant system resources does not verify the user's identity before executing. Attackers can exploit this to trigger critical functions without any credentials.

Extended Description

Missing authentication for critical functions is a common security flaw where developers protect the main application entry point but forget to verify identity for specific, powerful features within it. These unprotected functions might include administrative actions like user account deletion, financial transactions, data exports, or system configuration changes. Since no login check or session validation is performed, attackers can directly call these functions, often by manipulating URLs, API requests, or hidden form fields, leading to immediate compromise. To prevent this, implement consistent authentication checks across all application layers for any function that performs privileged operations or consumes high resources. Use a centralized security mechanism or middleware to enforce identity verification, avoiding scattered checks that are easy to miss. Always apply the principle of least privilege, ensuring every request is authenticated and authorized, not just those coming from the expected user interface.

Common Consequences 1

Scope: Access ControlOther

Impact: Gain Privileges or Assume IdentityVaries by Context

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, accessing administrative or other privileged functionality, or possibly even executing arbitrary code.

Detection Methods 8

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 AnalysisLimited

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.

Manual Static Analysis - Binary or BytecodeSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Dynamic Analysis with Automated Results InterpretationSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Web Application Scanner Web Services Scanner Database Scanners

Dynamic Analysis with Manual Results InterpretationSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Host Application Interface Scanner Fuzz Tester Framework-based Fuzzer

Manual Static Analysis - Source CodeSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections)

Automated Static Analysis - Source CodeSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer

Architecture or Design ReviewHigh

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Formal Methods / Correct-By-Construction ``` Cost effective for partial coverage: ``` Attack Modeling

Potential Mitigations 5

Phase: 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, including those channels that are assumed to be accessible only by authorized parties. 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.

Phase: 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 Client-Side Enforcement of Server-Side Security. 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.

Phase: Architecture and Design

Where possible, avoid implementing custom, "grow-your-own" authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment. These capabilities may avoid common weaknesses that are unique to authentication; support automatic auditing and tracking; and 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.

Phase: Architecture and Design

Strategy: 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 [REF-45].

Phase: ImplementationSystem ConfigurationOperation

When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data [REF-1297] [REF-1298] [REF-1302].

Demonstrative Examples 3

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

Code Example:Bad
Java
java

However, there is no authentication mechanism to ensure that the user creating this bank account object has the authority to create new bank accounts. Some authentication mechanisms should be used to verify that the user has the authority to create bank account objects.

The following Java code includes a boolean variable and method for authenticating a user. If the user has not been authenticated then the createBankAccount will not create the bank account object.

Code Example:

Good

Java

java

// authenticate user,*

java

ID : DX-153

In 2022, the OT:ICEFALL study examined products by 10 different Operational Technology (OT) vendors. The researchers reported 56 vulnerabilities and said that the products were "insecure by design" [REF-1283]. If exploited, these vulnerabilities often allowed adversaries to change how the products operated, ranging from denial of service to changing the code that the products executed. Since these products were often used in industries such as power, electrical, water, and others, there could even be safety implications.

Multiple vendors did not use any authentication for critical functionality in their OT products.

ID : DX-155

In 2021, a web site operated by PeopleGIS stored data of US municipalities in Amazon Web Service (AWS) Simple Storage Service (S3) buckets.

Code Example:Bad
Other
other

While it was not publicly disclosed how the data was protected after discovery, multiple options could have been considered.

Code Example:Good
Other
other

Observed Examples 17

CVE-2024-11680File-sharing PHP product does not check if user is logged in during requests for PHP library files under an includes/ directory, allowing configuration changes, code execution, and other impacts.

CVE-2022-31260Chain: a digital asset management program has an undisclosed backdoor in the legacy version of a PHP script (Hidden Functionality) that could allow an unauthenticated user to export metadata (Missing Authentication for Critical Function)

CVE-2022-29951TCP-based protocol in Programmable Logic Controller (PLC) has no authentication.

CVE-2022-29952Condition Monitor firmware uses a protocol that does not require authentication.

CVE-2022-30276SCADA-based protocol for bridging WAN and LAN traffic has no authentication.

CVE-2022-30313Safety Instrumented System uses proprietary TCP protocols with no authentication.

CVE-2022-30317Distributed Control System (DCS) uses a protocol that has no authentication.

CVE-2021-21972Chain: Cloud computing virtualization platform does not require authentication for upload of a tar format file (Missing Authentication for Critical Function), then uses .. path traversal sequences (Relative Path Traversal) in the file to access unexpected files, as exploited in the wild per CISA KEV.

CVE-2020-10263Bluetooth speaker does not require authentication for the debug functionality on the UART port, allowing root shell access

CVE-2021-23147WiFi router does not require authentication for its UART port, allowing adversaries with physical access to execute commands as root

CVE-2021-37415IT management product does not perform authentication for some REST API requests, as exploited in the wild per CISA KEV.

CVE-2020-13927Default setting in workflow management product allows all API requests without authentication, as exploited in the wild per CISA KEV.

CVE-2002-1810MFV. Access TFTP server without authentication and obtain configuration file with sensitive plaintext information.

CVE-2008-6827Agent software running at privileges does not authenticate incoming requests over an unprotected channel, allowing a Shatter" attack.

CVE-2004-0213Product enforces restrictions through a GUI but not through privileged APIs.

CVE-2020-15483monitor device allows access to physical UART debug port without authentication

CVE-2019-9201Programmable Logic Controller (PLC) does not have an authentication feature on its communication protocols.

References 10

The Art of Software Security Assessment

Mark Dowd, John McDonald, and Justin Schuh

Addison Wesley

2006

ID: REF-62

Top 25 Series - Rank 19 - Missing Authentication for Critical Function

Frank Kim

SANS Software Security Institute

23-02-2010

https://www.sans.org/blog/top-25-series-rank-19-missing-authentication-for-critical-function/(2025-07-29)

ID: REF-257

OWASP Enterprise Security API (ESAPI) Project

OWASP

https://owasp.org/www-project-enterprise-security-api/(2025-07-24)

ID: REF-45

OT:ICEFALL: The legacy of "insecure by design" and its implications for certifications and risk management

Forescout Vedere Labs

20-06-2022

https://www.forescout.com/resources/ot-icefall-report/

ID: REF-1283

Over 80 US Municipalities' Sensitive Information, Including Resident's Personal Data, Left Vulnerable in Massive Data Breach

WizCase

20-07-2021

https://www.wizcase.com/blog/us-municipality-breach-report/

ID: REF-1295

1,000 GB of local government data exposed by Massachusetts software company

Jonathan Greig

22-07-2021

https://www.zdnet.com/article/1000-gb-of-local-government-data-exposed-by-massachusetts-software-company/

ID: REF-1296

AWS Foundational Security Best Practices controls

Amazon

2022

https://docs.aws.amazon.com/securityhub/latest/userguide/securityhub-controls-reference.html(2023-04-07)

ID: REF-1297

Authentication and authorization in Azure App Service and Azure Functions

Microsoft

23-11-2021

https://learn.microsoft.com/en-us/azure/app-service/overview-authentication-authorization(2022-10-11)

ID: REF-1298

Authentication and authorization use cases

Google Cloud

11-10-2022

https://cloud.google.com/docs/authentication/use-cases(2022-10-11)

ID: REF-1302

State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation

Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, and Rama S. Moorthy

07-2014

https://www.ida.org/-/media/feature/publications/s/st/stateoftheart-resources-soar-for-software-vulnerability-detection-test-and-evaluation/p-5061.ashx(2025-09-05)

ID: REF-1479

Likelihood of Exploit

High

Applicable Platforms

Languages:

Not Language-Specific : Undetermined

Technologies:

Cloud Computing : UndeterminedICS/OT : Often

Modes of Introduction

Architecture and Design

Operation

Related Attack Patterns

Related Weaknesses

ChildOf:

Improper Authentication (CWE-287)

ChildOf:

Improper Authentication (CWE-287)

Taxonomy Mapping

PLOVER
Software Fault Patterns
ISA/IEC 62443
ISA/IEC 62443
ISA/IEC 62443
ISA/IEC 62443
ISA/IEC 62443