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Description
The product does not initialize critical variables, which causes the execution environment to use unexpected values.
Relationships
This table 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 still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
Base - a weakness
that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
Variant - a weakness
that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
Base - a weakness
that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
Variant - a weakness
that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
This table 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 "CISQ Quality Measures (2020)" (CWE-1305)
Nature
Type
ID
Name
ChildOf
Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
This table 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 "CISQ Data Protection Measures" (CWE-1340)
Nature
Type
ID
Name
ChildOf
Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the 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
This listing shows 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
Class: Not Language-Specific (Undetermined Prevalence)
Common Consequences
This table 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
This function attempts to extract a pair of numbers from a user-supplied string.
(bad code)
Example Language: C
void parse_data(char *untrusted_input){
int m, n, error; error = sscanf(untrusted_input, "%d:%d", &m, &n); if ( EOF == error ){
die("Did not specify integer value. Die evil hacker!\n");
} /* proceed assuming n and m are initialized correctly */
}
This code attempts to extract two integer values out of a formatted, user-supplied input. However, if an attacker were to provide an input of the form:
(attack code)
123:
then only the m variable will be initialized. Subsequent use of n may result in the use of an uninitialized variable (CWE-457).
Example 2
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 3
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 4
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);
} else {
if (password.equals(user.getPassword())) {
isUserAuthentic = true;
}
} return isUserAuthentic;
}
// methods for performing bank manager tasks ...
}
Example 5
This example will leave test_string in an unknown condition when i is the same value as err_val, because test_string is not initialized (CWE-456). Depending on where this code segment appears (e.g. within a function body), test_string might be random if it is stored on the heap or stack. If the variable is declared in static memory, it might be zero or NULL. Compiler optimization might contribute to the unpredictability of this address.
(bad code)
Example Language: C
char *test_string;
if (i != err_val)
{
test_string = "Hello World!";
}
printf("%s", test_string);
When the printf() is reached, test_string might be an unexpected address, so the printf might print junk strings (CWE-457).
To fix this code, there are a couple approaches to
making sure that test_string has been properly set once
it reaches the printf().
One solution would be to set test_string to an
acceptable default before the conditional:
(good code)
Example Language: C
char *test_string = "Done at the beginning";
if (i != err_val)
{
test_string = "Hello World!";
}
printf("%s", test_string);
Another solution is to ensure that each
branch of the conditional - including the default/else
branch - could ensure that test_string is set:
Chain: The return value of a function returning a pointer is not checked for success (CWE-252) resulting in the later use of an uninitialized variable (CWE-456) and a null pointer dereference (CWE-476)
Chain: Use of an unimplemented network socket operation pointing to an uninitialized handler function (CWE-456) causes a crash because of a null pointer dereference (CWE-476).
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.
Detection Methods
Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Effectiveness: High
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
[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.
Description
This table 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 "CISQ Quality Measures (2020)" (CWE-1305)
