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Common Weakness Enumeration

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Home > CWE List > CWE-391: Unchecked Error Condition (4.16)  
ID

CWE-391: Unchecked Error Condition

Weakness ID: 391
Vulnerability Mapping: PROHIBITED This CWE ID must not be used to map to real-world vulnerabilities
Abstraction: 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.
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+ Description
[PLANNED FOR DEPRECATION. SEE MAINTENANCE NOTES AND CONSIDER CWE-252, CWE-248, OR CWE-1069.] Ignoring exceptions and other error conditions may allow an attacker to induce unexpected behavior unnoticed.
+ 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.
Scope Impact Likelihood
Integrity
Other

Technical Impact: Varies by Context; Unexpected State; Alter Execution Logic

+ Potential Mitigations

Phase: Requirements

The choice between a language which has named or unnamed exceptions needs to be done. While unnamed exceptions exacerbate the chance of not properly dealing with an exception, named exceptions suffer from the up call version of the weak base class problem.

Phase: Requirements

A language can be used which requires, at compile time, to catch all serious exceptions. However, one must make sure to use the most current version of the API as new exceptions could be added.

Phase: Implementation

Catch all relevant exceptions. This is the recommended solution. Ensure that all exceptions are handled in such a way that you can be sure of the state of your system at any given moment.
+ 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" (CWE-1000)
Nature Type ID Name
ChildOf 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. 754 Improper Check for Unusual or Exceptional Conditions
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 "Software Development" (CWE-699)
Nature Type ID Name
MemberOf Category Category - a CWE entry that contains a set of other entries that share a common characteristic. 389 Error Conditions, Return Values, Status Codes
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 "Architectural Concepts" (CWE-1008)
Nature Type ID Name
MemberOf Category Category - a CWE entry that contains a set of other entries that share a common characteristic. 1020 Verify Message Integrity
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 "CISQ Quality Measures (2020)" (CWE-1305)
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. 703 Improper Check or Handling of Exceptional Conditions
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 "CISQ Data Protection Measures" (CWE-1340)
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. 703 Improper Check or Handling of Exceptional Conditions
+ 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 REALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ 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)

+ Likelihood Of Exploit
Medium
+ Demonstrative Examples

Example 1

The following code excerpt ignores a rarely-thrown exception from doExchange().

(bad code)
Example Language: Java 
try {
doExchange();
}
catch (RareException e) {

// this can never happen
}

If a RareException were to ever be thrown, the program would continue to execute as though nothing unusual had occurred. The program records no evidence indicating the special situation, potentially frustrating any later attempt to explain the program's behavior.


+ 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
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. 388 7PK - Errors
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 728 OWASP Top Ten 2004 Category A7 - Improper Error Handling
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 743 CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 746 CERT C Secure Coding Standard (2008) Chapter 13 - Error Handling (ERR)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 876 CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 877 CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 880 CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 962 SFP Secondary Cluster: Unchecked Status Condition
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1159 SEI CERT C Coding Standard - Guidelines 05. Floating Point (FLP)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1167 SEI CERT C Coding Standard - Guidelines 12. Error Handling (ERR)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1171 SEI CERT C Coding Standard - Guidelines 50. POSIX (POS)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1181 SEI CERT Perl Coding Standard - Guidelines 03. Expressions (EXP)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1405 Comprehensive Categorization: Improper Check or Handling of Exceptional Conditions
+ Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reasons: Potential Deprecation, Frequent Misuse, Frequent Misinterpretation

Rationale:

This entry is slated for deprecation; it has multiple widespread interpretations by CWE analysts. It combines information from three different taxonomies, but each taxonomy is talking about a slightly different issue.

Comments:

Consider CWE-252, CWE-1069, CWE-248, or other entries under CWE-754: Improper Check for Unusual or Exceptional Conditions or CWE-755: Improper Handling of Exceptional Conditions.
Suggestions:
CWE-ID Comment
CWE-252 Unchecked Return Value
CWE-1069 Empty Exception Block
CWE-248 Uncaught Exception
+ Notes

Other

When a programmer ignores an exception, they implicitly state that they are operating under one of two assumptions:

  • This method call can never fail.
  • It doesn't matter if this call fails.

Maintenance

This entry is slated for deprecation; it has multiple widespread interpretations by CWE analysts. It currently combines information from three different taxonomies, but each taxonomy is talking about a slightly different issue. CWE analysts might map to this entry based on any of these issues. 7PK has "Empty Catch Block" which has an association with empty exception block (CWE-1069); in this case, the exception has performed the check, but does not handle. In PLOVER there is "Unchecked Return Value" which is CWE-252, but unlike "Empty Catch Block" there isn't even a check of the issue - and "Unchecked Error Condition" implies lack of a check. For CLASP, "Uncaught Exception" (CWE-248) is associated with incorrect error propagation - uncovered in CWE 3.2 and earlier, at least. There are other issues related to error handling and checks.
+ Taxonomy Mappings
Mapped Taxonomy Name Node ID Fit Mapped Node Name
PLOVER Unchecked Return Value
7 Pernicious Kingdoms Empty Catch Block
CLASP Uncaught exception
OWASP Top Ten 2004 A7 CWE More Specific Improper Error Handling
CERT C Secure Coding ERR00-C Adopt and implement a consistent and comprehensive error-handling policy
CERT C Secure Coding ERR33-C CWE More Abstract Detect and handle standard library errors
CERT C Secure Coding ERR34-C CWE More Abstract Detect errors when converting a string to a number
CERT C Secure Coding FLP32-C Imprecise Prevent or detect domain and range errors in math functions
CERT C Secure Coding POS54-C CWE More Abstract Detect and handle POSIX library errors
SEI CERT Perl Coding Standard EXP31-PL Imprecise Do not suppress or ignore exceptions
Software Fault Patterns SFP4 Unchecked Status Condition
+ References
[REF-18] Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. URL validated: 2024-11-17.
+ Content History
+ Submissions
Submission Date Submitter Organization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification Date Modifier Organization
2008-07-01 Eric Dalci Cigital
updated Time_of_Introduction
2008-08-01 KDM Analytics
added/updated white box definitions
2008-08-15 Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08 CWE Content Team MITRE
updated Maintenance_Notes, Relationships, Other_Notes, Taxonomy_Mappings
2008-11-24 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2009-05-27 CWE Content Team MITRE
updated Demonstrative_Examples
2009-07-17 KDM Analytics
Improved the White_Box_Definition
2009-07-27 CWE Content Team MITRE
updated White_Box_Definitions
2011-06-01 CWE Content Team MITRE
updated Common_Consequences
2011-06-27 CWE Content Team MITRE
updated Common_Consequences
2011-09-13 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2012-05-11 CWE Content Team MITRE
updated Relationships
2012-10-30 CWE Content Team MITRE
updated Potential_Mitigations
2014-06-23 CWE Content Team MITRE
updated Other_Notes
2014-07-30 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2017-11-08 CWE Content Team MITRE
updated Applicable_Platforms, Modes_of_Introduction, Relationships, Taxonomy_Mappings, White_Box_Definitions
2019-01-03 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2019-06-20 CWE Content Team MITRE
updated Description, Maintenance_Notes
2020-02-24 CWE Content Team MITRE
updated References
2020-08-20 CWE Content Team MITRE
updated Relationships
2020-12-10 CWE Content Team MITRE
updated Relationships
2021-03-15 CWE Content Team MITRE
updated Description, Relationships
2021-07-20 CWE Content Team MITRE
updated Relationships
2023-04-27 CWE Content Team MITRE
updated Detection_Factors, Relationships, Time_of_Introduction
2023-06-29 CWE Content Team MITRE
updated Mapping_Notes
2024-02-29
(CWE 4.14, 2024-02-29)
CWE Content Team MITRE
updated Mapping_Notes
Page Last Updated: November 19, 2024