CWE

Common Weakness Enumeration

A Community-Developed List of Software & Hardware Weakness Types

CWE Top 25 Most Dangerous Weaknesses
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ID

CWE-756: Missing Custom Error Page

Weakness ID: 756
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The software does not return custom error pages to the user, possibly exposing sensitive information.
+ 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.755Improper Handling of Exceptional Conditions
ParentOfVariantVariant - 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.7J2EE Misconfiguration: Missing Custom Error Page
ParentOfVariantVariant - 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.12ASP.NET Misconfiguration: Missing Custom Error Page
CanPrecedeBaseBase - 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.209Generation of Error Message Containing Sensitive Information
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.389Error Conditions, Return Values, Status Codes
+ 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
Confidentiality

Technical Impact: Read Application Data

Attackers can leverage the additional information provided by a default error page to mount attacks targeted on the framework, database, or other resources used by the application.
+ Demonstrative Examples

Example 1

In the snippet below, an unchecked runtime exception thrown from within the try block may cause the container to display its default error page (which may contain a full stack trace, among other things).

(bad code)
Example Language: Java 
Public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
...
} catch (ApplicationSpecificException ase) {
logger.error("Caught: " + ase.toString());
}
}

Example 2

The mode attribute of the <customErrors> tag in the Web.config file defines whether custom or default error pages are used.

In the following insecure ASP.NET application setting, custom error message mode is turned off. An ASP.NET error message with detailed stack trace and platform versions will be returned.

(bad code)
Example Language: ASP.NET 
<customErrors mode="Off" />

A more secure setting is to set the custom error message mode for remote users only. No defaultRedirect error page is specified. The local user on the web server will see a detailed stack trace. For remote users, an ASP.NET error message with the server customError configuration setting and the platform version will be returned.

(good code)
Example Language: ASP.NET 
<customErrors mode="RemoteOnly" />

Another secure option is to set the mode attribute of the <customErrors> tag to use a custom page as follows:

(good code)
Example Language: ASP.NET 
<customErrors mode="On" defaultRedirect="YourErrorPage.htm" />
+ 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
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.963SFP Secondary Cluster: Exposed Data
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2009-03-03CWE Content TeamMITRE
New entry for reorganization of CWE-703.
+ Modifications
Modification DateModifierOrganization
2010-09-27CWE Content TeamMITRE
updated Description
2010-12-13CWE Content TeamMITRE
updated Description
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Relationships, Type
2021-03-15CWE Content TeamMITRE
updated Demonstrative_Examples
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Page Last Updated: July 20, 2021