The software does not initialize critical variables, which causes the execution environment to use unexpected values.
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)
Nature
Type
ID
Name
ChildOf
Base - a weakness that is described in an abstract fashion, but with sufficient details to infer specific methods for detection and prevention. More general than a Variant weakness, but more specific than a Class weakness.
Base - a weakness that is described in an abstract fashion, but with sufficient details to infer specific methods for detection and prevention. More general than a Variant weakness, but more specific than a Class weakness.
Base - a weakness that is described in an abstract fashion, but with sufficient details to infer specific methods for detection and prevention. More general than a Variant weakness, but more specific than a Class weakness.
Base - a weakness that is described in an abstract fashion, but with sufficient details to infer specific methods for detection and prevention. More general than a Variant weakness, but more specific than a Class weakness.
Variant - a weakness that is described at a very low level of detail, typically limited to a specific language or technology. More specific than a Base weakness.
Variant - a weakness that is described at a very low level of detail, typically limited to a specific language or technology. More specific than a Base weakness.
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.
Phase
Note
Implementation
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.
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.
Scope
Impact
Likelihood
Integrity Other
Technical Impact: Unexpected State; Quality Degradation; Varies by Context
The uninitialized data may be invalid, causing logic errors within the program. In some cases, this could result in a security problem.
Demonstrative Examples
Example 1
Here, an uninitialized field in a Java class is used in a seldom-called method, which would cause a NullPointerException to be thrown.
(bad code)
Example Language: Java
private User user; public void someMethod() {
// Do something interesting. ...
// Throws NPE if user hasn't been properly initialized. String username = user.getName();
}
Example 2
This code first authenticates a user, then allows a delete command if the user is an administrator.
(bad code)
Example Language: PHP
if (authenticate($username,$password) && setAdmin($username)){
$isAdmin = true;
} /.../
if ($isAdmin){
deleteUser($userToDelete);
}
The $isAdmin variable is set to true if the user is an admin, but is uninitialized otherwise. If PHP's register_globals feature is enabled, an attacker can set uninitialized variables like $isAdmin to arbitrary values, in this case gaining administrator privileges by setting $isAdmin to true.
Example 3
In the following Java code the BankManager class uses the user variable of the class User to allow authorized users to perform bank manager tasks. The user variable is initialized within the method setUser that retrieves the User from the User database. The user is then authenticated as unauthorized user through the method authenticateUser.
(bad code)
Example Language: Java
public class BankManager {
// user allowed to perform bank manager tasks private User user = null; private boolean isUserAuthentic = false;
// constructor for BankManager class public BankManager() {
...
}
// retrieve user from database of users public User getUserFromUserDatabase(String username){
...
}
// set user variable using username public void setUser(String username) {
this.user = getUserFromUserDatabase(username);
}
// authenticate user public boolean authenticateUser(String username, String password) {
if (username.equals(user.getUsername()) && password.equals(user.getPassword())) {
isUserAuthentic = true;
} return isUserAuthentic;
}
// methods for performing bank manager tasks ...
}
However, if the method setUser is not called before authenticateUser then the user variable will not have been initialized and will result in a NullPointerException. The code should verify that the user variable has been initialized before it is used, as in the following code.
(good code)
Example Language: Java
public class BankManager {
// user allowed to perform bank manager tasks private User user = null; private boolean isUserAuthentic = false;
// constructor for BankManager class public BankManager(String username) {
user = getUserFromUserDatabase(username);
}
// retrieve user from database of users public User getUserFromUserDatabase(String username) {...}
// authenticate user public boolean authenticateUser(String username, String password) {
if (user == null) {
System.out.println("Cannot find user " + username);
Array variable not initialized in PHP application, leading to resultant SQL injection.
Potential Mitigations
Phase: Implementation
Check that critical variables are initialized.
Phase: Testing
Use a static analysis tool to spot non-initialized variables.
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.
Nature
Type
ID
Name
MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.
View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).
This weakness is a major factor in a number of resultant weaknesses, especially in web applications that allow global variable initialization (such as PHP) with libraries that can be directly requested.
Research Gap
It is highly likely that a large number of resultant weaknesses have missing initialization as a primary factor, but researcher reports generally do not provide this level of detail.
Taxonomy Mappings
Mapped Taxonomy Name
Node ID
Fit
Mapped Node Name
PLOVER
Missing Initialization
Software Fault Patterns
SFP1
Glitch in computation
CERT C Secure Coding
ERR30-C
CWE More Abstract
Set errno to zero before calling a library function known to set errno, and check errno only after the function returns a value indicating failure
CERT Perl Secure Coding
DCL04-PL
Exact
Always initialize local variables
CERT Perl Secure Coding
DCL33-PL
Imprecise
Declare identifiers before using them
References
[REF-62] Mark Dowd, John McDonald
and Justin Schuh. "The Art of Software Security Assessment". Chapter 7, "Variable Initialization", Page 312. 1st Edition. Addison Wesley. 2006.
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March 29, 2018
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Description
Relevant to the view "Research Concepts" (CWE-1000)
