CWE-306: Missing Authentication for Critical Function
Missing Authentication for Critical Function
Weakness ID: 306 (Weakness Variant)
Status: Draft
Description
Description Summary
The software does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
Time of Introduction
Architecture and Design
Applicable Platforms
Languages
Language-independent
Common Consequences
Scope
Effect
Access Control
Other
Technical Impact: Gain privileges / assume
identity; Other
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.
Likelihood of Exploit
Medium to High
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.
These may be more effective than strictly automated techniques. This
is especially the case with weaknesses that are related to design and
business rules.
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.
Effectiveness: Limited
Demonstrative Examples
Example 1
In the following Java example the method createBankAccount is used
to create a BankAccount object for a bank management
application.
(Bad Code)
Example
Language: Java
public BankAccount createBankAccount(String accountNumber, String
accountType,
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.
(Good Code)
Example
Language: Java
private boolean isUserAuthentic = false;
// authenticate user,
// if user is authenticated then set variable to true
// otherwise set variable to false
public boolean authenticateUser(String username, String password)
{
...
}
public BankAccount createNewBankAccount(String accountNumber,
String accountType,
Product enforces restrictions through a GUI but
not through privileged APIs.
Potential Mitigations
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. 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 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.
Phase: 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.
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 [R.306.3].
[R.306.1] [REF-7] Mark Dowd, John McDonald
and Justin Schuh. "The Art of Software Security Assessment". Chapter 2, "Common Vulnerabilities of Authentication," Page
36. 1st Edition. Addison Wesley. 2006.
Description
