CWE-665: Improper Initialization

Description

The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

This can have security implications when the associated resource is expected to have certain properties or values, such as a variable that determines whether a user has been authenticated or not.

Abstraction: ClassAn abstract weakness, independent of any specific language or technology.
Likelihood of exploit: Medium
Status: Draft

Common consequences

Confidentiality
Read Memory; Read Application Data
When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Access Control
Bypass Protection Mechanism
If security-critical decisions rely on a variable having a 0 or equivalent value, and the programming language performs this initialization on behalf of the programmer, then a bypass of security may occur.
Availability
DoS: Crash, Exit, or Restart
The uninitialized data may contain values that cause program flow to change in ways that the programmer did not intend. For example, if an uninitialized variable is used as an array index in C, then its previous contents may produce an index that is outside the range of the array, possibly causing a crash or an exit in...

Potential mitigations

RequirementsLanguage Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable's type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.
Architecture and Design
Identify all variables and data stores that receive information from external sources, and apply input validation to make sure that they are only initialized to expected values.
Implementation
Explicitly initialize all your variables and other data stores, either during declaration or just before the first usage.
Implementation
Pay close attention to complex conditionals that affect initialization, since some conditions might not perform the initialization.
Implementation
Avoid race conditions (CWE-362) during initialization routines.
Build and Compilation
Run or compile your product with settings that generate warnings about uninitialized variables or data.

Related weaknesses

Parent weaknesses

CWE-664Improper Control of a Resource Through its Lifetime

Child weaknesses

CAPEC attack patterns that exploit it

Description

The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

This can have security implications when the associated resource is expected to have certain properties or values, such as a variable that determines whether a user has been authenticated or not.

Common consequences

Confidentiality

Read Memory; Read Application Data

When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.

Access Control

Bypass Protection Mechanism

If security-critical decisions rely on a variable having a 0 or equivalent value, and the programming language performs this initialization on behalf of the programmer, then a bypass of security may occur.

Availability

DoS: Crash, Exit, or Restart

The uninitialized data may contain values that cause program flow to change in ways that the programmer did not intend. For example, if an uninitialized variable is used as an array index in C, then its previous contents may produce an index that is outside the range of the array, possibly causing a crash or an exit in...

Potential mitigations

RequirementsLanguage Selection

Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable's type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.

Architecture and Design

Identify all variables and data stores that receive information from external sources, and apply input validation to make sure that they are only initialized to expected values.

Implementation

Explicitly initialize all your variables and other data stores, either during declaration or just before the first usage.

Implementation

Pay close attention to complex conditionals that affect initialization, since some conditions might not perform the initialization.

Implementation

Avoid race conditions (CWE-362) during initialization routines.

Build and Compilation

Run or compile your product with settings that generate warnings about uninitialized variables or data.