CWE

Common Weakness Enumeration

A community-developed list of SW & HW weaknesses that can become vulnerabilities

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ID

CWE-561: Dead Code

Weakness ID: 561
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: BaseBase - 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.
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+ Description
The product contains dead code, which can never be executed.
+ Extended Description
Dead code is code that can never be executed in a running program. The surrounding code makes it impossible for a section of code to ever be executed.
+ Relationships
Section HelpThis 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)
NatureTypeIDName
ChildOfClassClass - 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.1164Irrelevant Code
CanFollowBaseBase - 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.570Expression is Always False
CanFollowBaseBase - 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.571Expression is Always True
Section HelpThis 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 "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1006Bad Coding Practices
+ 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.
PhaseNote
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)

+ 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.
ScopeImpactLikelihood
Other

Technical Impact: Quality Degradation

Dead code that results from code that can never be executed is an indication of problems with the source code that needs to be fixed and is an indication of poor quality.
Other

Technical Impact: Reduce Maintainability

+ Demonstrative Examples

Example 1

The condition for the second if statement is impossible to satisfy. It requires that the variables be non-null. However, on the only path where s can be assigned a non-null value, there is a return statement.

(bad code)
Example Language: C++ 
String s = null;
if (b) {
s = "Yes";
return;
}

if (s != null) {
Dead();
}

Example 2

In the following class, two private methods call each other, but since neither one is ever invoked from anywhere else, they are both dead code.

(bad code)
Example Language: Java 
public class DoubleDead {
private void doTweedledee() {
doTweedledumb();
}
private void doTweedledumb() {
doTweedledee();
}
public static void main(String[] args) {
System.out.println("running DoubleDead");
}
}

(In this case it is a good thing that the methods are dead: invoking either one would cause an infinite loop.)

Example 3

The field named glue is not used in the following class. The author of the class has accidentally put quotes around the field name, transforming it into a string constant.

(bad code)
Example Language: Java 
public class Dead {
String glue;

public String getGlue() {
return "glue";
}
}
+ Observed Examples
ReferenceDescription
chain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversary-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint).
+ Potential Mitigations

Phase: Implementation

Remove dead code before deploying the application.

Phase: Testing

Use a static analysis tool to spot dead code.
+ Weakness Ordinalities
OrdinalityDescription
Indirect
(where the weakness is a quality issue that might indirectly make it easier to introduce security-relevant weaknesses or make them more difficult to detect)
+ Detection Methods

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Attack Modeling

Effectiveness: High

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Binary / Bytecode Quality Analysis
  • Compare binary / bytecode to application permission manifest

Effectiveness: High

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Automated Monitored Execution

Effectiveness: SOAR Partial

Automated Static Analysis

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Permission Manifest Analysis

Effectiveness: SOAR Partial

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Source Code Quality Analyzer
Cost effective for partial coverage:
  • Warning Flags
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: High

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Manual Source Code Review (not inspections)
Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source

Effectiveness: High

+ 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.
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.747CERT C Secure Coding Standard (2008) Chapter 14 - Miscellaneous (MSC)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.883CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)
MemberOfViewView - 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).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.886SFP Primary Cluster: Unused entities
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1130CISQ Quality Measures (2016) - Maintainability
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1186SEI CERT Perl Coding Standard - Guidelines 50. Miscellaneous (MSC)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1307CISQ Quality Measures - Maintainability
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1412Comprehensive Categorization: Poor Coding Practices
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CERT C Secure CodingMSC07-CDetect and remove dead code
SEI CERT Perl Coding StandardMSC00-PLExactDetect and remove dead code
Software Fault PatternsSFP2Unused Entities
OMG ASCMMASCMM-MNT-20
+ References
[REF-960] Object Management Group (OMG). "Automated Source Code Maintainability Measure (ASCMM)". ASCMM-MNT-20. 2016-01. <https://www.omg.org/spec/ASCMM/>. URL validated: 2023-04-07.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
Anonymous Tool Vendor (under NDA)
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Description, Relationships, Other_Notes, Taxonomy_Mappings
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples
2009-07-27CWE Content TeamMITRE
updated Demonstrative_Examples
2009-10-29CWE Content TeamMITRE
updated Common_Consequences, Other_Notes
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-06-23CWE Content TeamMITRE
updated Observed_Examples
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2019-01-03CWE Content TeamMITRE
updated Common_Consequences, References, Relationships, Taxonomy_Mappings, Weakness_Ordinalities
2019-06-20CWE Content TeamMITRE
updated Type
2020-02-24CWE Content TeamMITRE
updated Applicable_Platforms, Observed_Examples, Relationships
2020-08-20CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated Relationships
2021-07-20CWE Content TeamMITRE
updated Observed_Examples
2023-01-31CWE Content TeamMITRE
updated Description
2023-04-27CWE Content TeamMITRE
updated References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
2024-02-29
(CWE 4.14, 2024-02-29)
CWE Content TeamMITRE
updated Demonstrative_Examples
Page Last Updated: February 29, 2024