Base weakness

Draft

CWE-306: Missing Authentication for Critical Function

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

1,379

Recorded CVEs

With this primary weakness

KEVs

In the CISA KEV catalog

High

Likelihood of exploit

Per MITRE

Base

Abstraction

MITRE classification

Overview

CWE-306 (Missing Authentication for Critical Function) is a base-level software weakness catalogued by MITRE in the Common Weakness Enumeration (CWE). It describes a recurring type of mistake that can lead to exploitable security vulnerabilities.

Real-world CVEs

How to prevent it

Practical mitigations for CWE-306, grouped by where in the lifecycle they apply.

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.

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, "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.

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 [REF-45].

Implementation

System Configuration

Operation

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].

Code examples

Illustrative examples from MITRE showing how the weakness appears in code.

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

Vulnerable example

java

public BankAccount createBankAccount(String accountNumber, String accountType,

Safe example

java

private boolean isUserAuthentic = false;

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.

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

Vulnerable example

other

A security researcher found 86 S3 buckets that could be accessed without authentication (CWE-306) and stored data unencrypted (CWE-312). These buckets exposed over 1000 GB of data and 1.6 million files including physical addresses, phone numbers, tax documents, pictures of driver's license IDs, etc. [REF-1296] [REF-1295]

Safe example

other

The sensitive information could have been protected by ensuring that the buckets did not have public read access, e.g., by enabling the s3-account-level-public-access-blocks-periodic rule to Block Public Access. In addition, the data could have been encrypted at rest using the appropriate S3 settings, e.g., by enabling server-side encryption using the s3-bucket-server-side-encryption-enabled setting. Other settings are available to further prevent bucket data from being leaked. [REF-1297]

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

Illustrative examples

Real CVEs that MITRE cites as examples of this weakness.

CVE-2024-11680
CISA KEV
— File-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-2021-21972
CISA KEV
— Chain: Cloud computing virtualization platform does not require authentication for upload of a tar format file (CWE-306), then uses .. path traversal sequences (CWE-23) in the file to access unexpected files, as exploited in the wild per CISA KEV.
CVE-2021-37415
CISA KEV
— IT management product does not perform authentication for some REST API requests, as exploited in the wild per CISA KEV.
CVE-2020-13927
CISA KEV
— Default setting in workflow management product allows all API requests without authentication, as exploited in the wild per CISA KEV.
CVE-2022-31260 — Chain: a digital asset management program has an undisclosed backdoor in the legacy version of a PHP script (CWE-912) that could allow an unauthenticated user to export metadata (CWE-306)
CVE-2022-29951 — TCP-based protocol in Programmable Logic Controller (PLC) has no authentication.
CVE-2022-29952 — Condition Monitor firmware uses a protocol that does not require authentication.
CVE-2022-30276 — SCADA-based protocol for bridging WAN and LAN traffic has no authentication.
CVE-2022-30313 — Safety Instrumented System uses proprietary TCP protocols with no authentication.
CVE-2022-30317 — Distributed Control System (DCS) uses a protocol that has no authentication.
CVE-2020-10263 — Bluetooth speaker does not require authentication for the debug functionality on the UART port, allowing root shell access
CVE-2021-23147 — WiFi router does not require authentication for its UART port, allowing adversaries with physical access to execute commands as root
CVE-2002-1810 — MFV. Access TFTP server without authentication and obtain configuration file with sensitive plaintext information.
CVE-2008-6827 — Agent software running at privileges does not authenticate incoming requests over an unprotected channel, allowing a Shatter" attack.
CVE-2004-0213 — Product enforces restrictions through a GUI but not through privileged APIs.
CVE-2020-15483 — monitor device allows access to physical UART debug port without authentication
CVE-2019-9201 — Programmable Logic Controller (PLC) does not have an authentication feature on its communication protocols.

CWE-306: Missing Authentication for Critical Function

Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

Applies to

How to prevent it

How to detect it

Manual Analysis

Automated Static Analysis

Manual Static Analysis - Binary or Bytecode

Dynamic Analysis with Automated Results Interpretation

Dynamic Analysis with Manual Results Interpretation

Manual Static Analysis - Source Code

Automated Static Analysis - Source Code

Architecture or Design Review

Code examples

Illustrative examples

Terminology & mappings

Mapped taxonomies

Attack patterns

Frequently asked questions

What is CWE-306?

What CVEs are caused by CWE-306?

How do you prevent CWE-306?

How is CWE-306 detected?

What are the consequences of CWE-306?

Is CWE-306 actively exploited?

References

Stay ahead of CWE-306

Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

Applies to

How to prevent it

How to detect it

Manual Analysis

Automated Static Analysis

Manual Static Analysis - Binary or Bytecode

Dynamic Analysis with Automated Results Interpretation

Dynamic Analysis with Manual Results Interpretation

Manual Static Analysis - Source Code

Automated Static Analysis - Source Code

Architecture or Design Review

Code examples

Illustrative examples

Related weaknesses

Parent

Child

Terminology & mappings

Mapped taxonomies

Attack patterns

Frequently asked questions

What is CWE-306?

What CVEs are caused by CWE-306?

How do you prevent CWE-306?

How is CWE-306 detected?

What are the consequences of CWE-306?

Is CWE-306 actively exploited?

References

Stay ahead of CWE-306