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Home > CWE List > CWE-1023: Incomplete Comparison with Missing Factors (4.18)
ID
CWE Glossary Definition

CWE-1023: Incomplete Comparison with Missing Factors

Weakness ID: 1023
Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class 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.
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Description
The product performs a comparison between entities that must consider multiple factors or characteristics of each entity, but the comparison does not include one or more of these factors.
Extended Description
An incomplete comparison can lead to resultant weaknesses, e.g., by operating on the wrong object or making a security decision without considering a required factor.
Common Consequences
Section HelpThis 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.
Impact Details

Alter Execution Logic; Bypass Protection Mechanism

Scope: Integrity, Access Control

Potential Mitigations
Phase(s) Mitigation

Testing
Thoroughly test the comparison scheme before deploying code into production. Perform positive testing as well as negative testing.
Relationships
Section Help 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" (View-1000)
Nature Type ID Name
ChildOf Pillar Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things. 697 Incorrect Comparison
ParentOf Base 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. 184 Incomplete List of Disallowed Inputs
ParentOf Variant 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. 187 Partial String Comparison
ParentOf Base 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. 478 Missing Default Case in Multiple Condition Expression
ParentOf Base 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. 839 Numeric Range Comparison Without Minimum Check
Modes Of Introduction
Section HelpThe 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
Section HelpThis 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)

Demonstrative Examples

Example 1


Consider an application in which Truck objects are defined to be the same if they have the same make, the same model, and were manufactured in the same year.

(bad code)
Example Language: Java
public class Truck {
private String make;
private String model;
private int year;

public boolean equals(Object o) {
if (o == null) return false;
if (o == this) return true;
if (!(o instanceof Truck)) return false;

Truck t = (Truck) o;

return (this.make.equals(t.getMake()) && this.model.equals(t.getModel()));
}
}

Here, the equals() method only checks the make and model of the Truck objects, but the year of manufacture is not included.



Example 2


This example defines a fixed username and password. The AuthenticateUser() function is intended to accept a username and a password from an untrusted user, and check to ensure that it matches the username and password. If the username and password match, AuthenticateUser() is intended to indicate that authentication succeeded.

(bad code)
Example Language: C
/* Ignore CWE-259 (hard-coded password) and CWE-309 (use of password system for authentication) for this example. */

char *username = "admin";
char *pass = "password";

int AuthenticateUser(char *inUser, char *inPass) {
if (strncmp(username, inUser, strlen(inUser))) {
logEvent("Auth failure of username using strlen of inUser");
return(AUTH_FAIL);
}
if (! strncmp(pass, inPass, strlen(inPass))) {
logEvent("Auth success of password using strlen of inUser");
return(AUTH_SUCCESS);
}
else {
logEvent("Auth fail of password using sizeof");
return(AUTH_FAIL);
}
}

int main (int argc, char **argv) {
int authResult;

if (argc < 3) {
ExitError("Usage: Provide a username and password");
}
authResult = AuthenticateUser(argv[1], argv[2]);
if (authResult == AUTH_SUCCESS) {
DoAuthenticatedTask(argv[1]);
}
else {
ExitError("Authentication failed");
}
}

In AuthenticateUser(), the strncmp() call uses the string length of an attacker-provided inPass parameter in order to determine how many characters to check in the password. So, if the attacker only provides a password of length 1, the check will only examine the first byte of the application's password before determining success.

As a result, this partial comparison leads to improper authentication (CWE-287).

Any of these passwords would still cause authentication to succeed for the "admin" user:

(attack code)
p
pa
pas
pass

This significantly reduces the search space for an attacker, making brute force attacks more feasible.

The same problem also applies to the username, so values such as "a" and "adm" will succeed for the username.

While this demonstrative example may not seem realistic, see the Observed Examples for CVE entries that effectively reflect this same weakness.



Selected Observed Examples

Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

Reference Description
PHP remote file inclusion in web application that filters "http" and "https" URLs, but not "ftp".
Product does not prevent access to restricted directories due to partial string comparison with a public directory
Weakness Ordinalities
Ordinality Description
Primary
(where the weakness exists independent of other weaknesses)
Memberships
Section HelpThis 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 CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1397 Comprehensive Categorization: Comparison
Vulnerability Mapping Notes
Usage ALLOWED-WITH-REVIEW
(this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason Abstraction

Rationale

This CWE entry is a Class and might have Base-level children that would be more appropriate

Comments

Examine children of this entry to see if there is a better fit
Content History
Submissions
Submission Date Submitter Organization
2018年01月04日
(CWE 3.1, 2018年03月29日) 		CWE Content Team MITRE
Modifications
Modification Date Modifier Organization
2023年10月26日 CWE Content Team MITRE
updated Observed_Examples
2023年06月29日 CWE Content Team MITRE
updated Mapping_Notes
2023年04月27日 CWE Content Team MITRE
updated Relationships
2023年01月31日 CWE Content Team MITRE
updated Description
2021年03月15日 CWE Content Team MITRE
updated Demonstrative_Examples
2020年02月24日 CWE Content Team MITRE
updated Description, Relationships, Type
2019年01月03日 CWE Content Team MITRE
updated Relationships
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Page Last Updated: September 09, 2025

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