CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
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ID

CWE-578: EJB Bad Practices: Use of Class Loader

Weakness ID: 578
Abstraction: Variant
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The program violates the Enterprise JavaBeans (EJB) specification by using the class loader.
+ Extended Description
The Enterprise JavaBeans specification requires that every bean provider follow a set of programming guidelines designed to ensure that the bean will be portable and behave consistently in any EJB container. In this case, the program violates the following EJB guideline: "The enterprise bean must not attempt to create a class loader; obtain the current class loader; set the context class loader; set security manager; create a new security manager; stop the JVM; or change the input, output, and error streams." The specification justifies this requirement in the following way: "These functions are reserved for the EJB container. Allowing the enterprise bean to use these functions could compromise security and decrease the container's ability to properly manage the runtime environment."
+ Relationships

The table(s) below 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 general than a Base weakness.573Improper Following of Specification by Caller
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More general than a Base weakness.573Improper Following of Specification by Caller
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and Design
Implementation
+ Applicable Platforms
The listings below show 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

Java (Undetermined Prevalence)

+ Common Consequences

The table below 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
Integrity
Availability
Other

Technical Impact: Execute Unauthorized Code or Commands; Varies by Context

+ Demonstrative Examples

Example 1

The following Java example is a simple stateless Enterprise JavaBean that retrieves the interest rate for the number of points for a mortgage. The interest rates for various points are retrieved from an XML document on the local file system, and the EJB uses the Class Loader for the EJB class to obtain the XML document from the local file system as an input stream.

(bad code)
Example Language: Java 
@Stateless
public class InterestRateBean implements InterestRateRemote {
private Document interestRateXMLDocument = null;

public InterestRateBean() {
try {

// get XML document from the local filesystem as an input stream

// using the ClassLoader for this class
ClassLoader loader = this.getClass().getClassLoader();
InputStream in = loader.getResourceAsStream(Constants.INTEREST_RATE_FILE);


DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
interestRateXMLDocument = db.parse(interestRateFile);
} catch (IOException ex) {...}
}
public BigDecimal getInterestRate(Integer points) {
return getInterestRateFromXML(points);
}

/* member function to retrieve interest rate from XML document on the local file system */

private BigDecimal getInterestRateFromXML(Integer points) {...}
}

This use of the Java Class Loader class within any kind of Enterprise JavaBean violates the restriction of the EJB specification against obtaining the current class loader as this could compromise the security of the application using the EJB.

Example 2

An EJB is also restricted from creating a custom class loader and creating a class and instance of a class from the class loader, as shown in the following example.

(bad code)
Example Language: Java 
@Stateless
public class LoaderSessionBean implements LoaderSessionRemote {
public LoaderSessionBean() {
try {
ClassLoader loader = new CustomClassLoader();
Class c = loader.loadClass("someClass");
Object obj = c.newInstance();
/* perform some task that uses the new class instance member variables or functions */
...
} catch (Exception ex) {...}
}

public class CustomClassLoader extends ClassLoader {

}
}
+ Potential Mitigations

Phases: Architecture and Design; Implementation

Do not use the Class Loader when writing EJBs.
+ 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.
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1001SFP Secondary Cluster: Use of an Improper API
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
Software Fault PatternsSFP3Use of an improper API
+ Content History
Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes
2009-10-29CWE Content TeamMITRE
updated Description, Other_Notes
2009-12-28CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-06-27CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings

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Page Last Updated: March 29, 2018