541
Applicable Platforms
Language : Java (Prevalence = Undetermined)
Common Consequences
Scope Impact Likelihood
Confidentiality Read Application Data
Potential Mitigations
Phase: Implementation
Do not expose sensitive error information to the user.
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.
Example Language: Java (Bad)
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
CWE Version 4.14
CWE-538: Insertion of Sensitive Information into Externally-Accessible File or Directory
CWE-538: Insertion of Sensitive Information
into Externally-Accessible File or Directory 1248
servlet will raise a FailedLoginException and output the failed login message to the error page of
the service.
Example Language: Java (Bad)
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.
MemberOf Relationships
This MemberOf relationships table shows additional CWE Catgeories 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 Page
MemberOf 963 SFP Secondary Cluster: Exposed Data 888 2400
MemberOf 1349 OWASP Top Ten 2021 Category A05:2021 - Security
Misconfiguration
1344 2493
MemberOf 1417 Comprehensive Categorization: Sensitive Information
Exposure
1400 2548
CWE-538: Insertion of Sensitive Information into Externally-Accessible File or
Directory
Weakness ID : 538
Structure : Simple
Abstraction : Base
Description
The product places sensitive information into files or directories that are accessible to actors who
are allowed to have access to the files, but not to the sensitive information.
Relationships
CWE Version 4.14
CWE-538: Insertion of Sensitive Information into Externally-Accessible File or Directory
CWE-538: Insertion of Sensitive Information
into Externally-Accessible File or Directory