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-537: Information Exposure Through Java Runtime Error Message

Weakness ID: 537
Abstraction: Variant
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
In many cases, an attacker can leverage the conditions that cause unhandled exception errors in order to gain unauthorized access to the system.
+ 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
ChildOfBaseBase - a weakness that is described in an abstract fashion, but with sufficient details to infer specific methods for detection and prevention. More general than a Variant weakness, but more specific than a Class weakness.210Information Exposure Through Self-generated Error Message
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfBaseBase - a weakness that is described in an abstract fashion, but with sufficient details to infer specific methods for detection and prevention. More general than a Variant weakness, but more specific than a Class weakness.210Information Exposure Through Self-generated Error Message
+ 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
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

Technical Impact: Read Application Data

+ Demonstrative Examples

Example 1

In the following Java example the class InputFileRead enables an input file to be read using a FileReader object. In the constructor of this class a default input file path is set to some directory on the local file system and the method setInputFile must be called to set the name of the input file to be read in the default directory. The method readInputFile will create the FileReader object and will read the contents of the file. If the method setInputFile is not called prior to calling the method readInputFile then the File object will remain null when initializing the FileReader object. A Java RuntimeException will be raised, and an error message will be output to the user.

(bad code)
Example Language: Java 
public class InputFileRead {
private File readFile = null;
private FileReader reader = null;
private String inputFilePath = null;
private final String DEFAULT_FILE_PATH = "c:\\somedirectory\\";

public InputFileRead() {
inputFilePath = DEFAULT_FILE_PATH;
}

public void setInputFile(String inputFile) {

/* Assume appropriate validation / encoding is used and privileges / permissions are preserved */
}

public void readInputFile() {
try {
reader = new FileReader(readFile);
...
} catch (RuntimeException rex) {
System.err.println("Error: Cannot open input file in the directory " + inputFilePath);
System.err.println("Input file has not been set, call setInputFile method before calling readInputFile");


} catch (FileNotFoundException ex) {...}
}
}

However, the error message output to the user contains information regarding the default directory on the local file system. This information can be exploited and may lead to unauthorized access or use of the system. Any Java RuntimeExceptions that are handled should not expose sensitive information to the user.

Example 2

In the example below, the BankManagerLoginServlet servlet class will process a login request to determine if a user is authorized to use the BankManager Web service. The doPost method will retrieve the username and password from the servlet request and will determine if the user is authorized. If the user is authorized the servlet will go to the successful login page. Otherwise, the servlet will raise a FailedLoginException and output the failed login message to the error page of the service.

(bad code)
Example Language: Java 
public class BankManagerLoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {

// Get username and password from login page request
String username = request.getParameter("username");
String password = request.getParameter("password");
// Authenticate user
BankManager bankMgr = new BankManager();
boolean isAuthentic = bankMgr.authenticateUser(username, password);
// If user is authenticated then go to successful login page
if (isAuthentic) {
request.setAttribute("login", new String("Login Successful."));
getServletContext().getRequestDispatcher("/BankManagerServiceLoggedIn.jsp"). forward(request, response);
}
else {

// Otherwise, raise failed login exception and output unsuccessful login message to error page
throw new FailedLoginException("Failed Login for user " + username + " with password " + password);
}
} catch (FailedLoginException ex) {

// output failed login message to error page
request.setAttribute("error", new String("Login Error"));
request.setAttribute("message", ex.getMessage());
getServletContext().getRequestDispatcher("/ErrorPage.jsp").forward(request, response);
}
}

However, the output message generated by the FailedLoginException includes the user-supplied password. Even if the password is erroneous, it is probably close to the correct password. Since it is printed to the user's page, anybody who can see the screen display will be able to see the password. Also, if the page is cached, the password might be written to disk.

+ Potential Mitigations

Phase: Implementation

Do not expose sensitive error information to the user.
+ 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.963SFP Secondary Cluster: Exposed Data
+ Content History
Submissions
Submission DateSubmitterOrganization
Anonymous Tool Vendor (under NDA)
Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2010-02-16CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Demonstrative_Examples, Name
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Taxonomy_Mappings
Previous Entry Names
Change DatePrevious Entry Name
2011-03-29Information Leak Through Java Runtime Error Message

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Page Last Updated: March 29, 2018