CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
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ID

CWE-453: Insecure Default Variable Initialization

Weakness ID: 453
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software, by default, initializes an internal variable with an insecure or less secure value than is possible.
+ Relationships

The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass665Improper Initialization
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory452Initialization and Cleanup Errors
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and Design
Implementation
Operation
+ Applicable Platforms
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

PHP (Sometimes Prevalent)

Class: Language-Independent (Undetermined Prevalence)

+ Common Consequences

The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
Integrity

Technical Impact: Modify Application Data

An attacker could gain access to and modify sensitive data or system information.
+ Demonstrative Examples

Example 1

This code attempts to login a user using credentials from a POST request:

(bad code)
Example Language: PHP 
// $user and $pass automatically set from POST request
if (login_user($user,$pass)) {
$authorized = true;

}
...

if ($authorized) {
generatePage();

}

Because the $authorized variable is never initialized, PHP will automatically set $authorized to any value included in the POST request if register_globals is enabled. An attacker can send a POST request with an unexpected third value 'authorized' set to 'true' and gain authorized status without supplying valid credentials.

Here is a fixed version:

(bad code)
Example Language: PHP 
$user = $_POST['user'];
$pass = $_POST['pass'];
$authorized = false;
if (login_user($user,$pass)) {
$authorized = true;

}
...

This code avoids the issue by initializing the $authorized variable to false and explicitly retrieving the login credentials from the $_POST variable. Regardless, register_globals should never be enabled and is disabled by default in current versions of PHP.

+ Potential Mitigations

Phase: System Configuration

Disable or change default settings when they can be used to abuse the system. Since those default settings are shipped with the product they are likely to be known by a potential attacker who is familiar with the product. For instance, default credentials should be changed or the associated accounts should be disabled.
+ Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView884CWE Cross-section
MemberOfCategoryCategory966SFP Secondary Cluster: Other Exposures
+ Notes

Maintenance

This overlaps other categories, probably should be split into separate items.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERInsecure default variable initialization
+ Content History
Submissions
Submission DateSubmitterOrganization
PLOVER
Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Applicable_Platforms, Relationships, Other_Notes, Taxonomy_Mappings
2010-06-21CWE Content TeamMITRE
updated Maintenance_Notes, Other_Notes
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms

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Page Last Updated: January 18, 2018