Exposure of Sensitive Information to an Unauthorized Actor

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.


Description

There are many different kinds of mistakes that introduce information exposures. The severity of the error can range widely, depending on the context in which the product operates, the type of sensitive information that is revealed, and the benefits it may provide to an attacker. Some kinds of sensitive information include:

private, personal information, such as personal messages, financial data, health records, geographic location, or contact details

system status and environment, such as the operating system and installed packages

business secrets and intellectual property

network status and configuration

the product's own code or internal state

metadata, e.g. logging of connections or message headers

indirect information, such as a discrepancy between two internal operations that can be observed by an outsider

Information might be sensitive to different parties, each of which may have their own expectations for whether the information should be protected. These parties include:

the product's own users

people or organizations whose information is created or used by the product, even if they are not direct product users

the product's administrators, including the admins of the system(s) and/or networks on which the product operates

the developer

Information exposures can occur in different ways:

the code

explicitly inserts

sensitive information into resources or messages that are intentionally made accessible to unauthorized actors, but should not contain the information - i.e., the information should have been "scrubbed" or "sanitized"

a different weakness or mistake

indirectly inserts

the sensitive information into resources, such as a web script error revealing the full system path of the program.

the code manages resources that intentionally contain sensitive information, but the resources are

unintentionally made accessible

to unauthorized actors. In this case, the information exposure is resultant - i.e., a different weakness enabled the access to the information in the first place.

It is common practice to describe any loss of confidentiality as an "information exposure," but this can lead to overuse of CWE-200 in CWE mapping. From the CWE perspective, loss of confidentiality is a technical impact that can arise from dozens of different weaknesses, such as insecure file permissions or out-of-bounds read. CWE-200 and its lower-level descendants are intended to cover the mistakes that occur in behaviors that explicitly manage, store, transfer, or cleanse sensitive information.

Demonstrations

The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

The following code checks validity of the supplied username and password and notifies the user of a successful or failed login.

my $username=param('username');
my $password=param('password');

if (IsValidUsername($username) == 1)
{
  if (IsValidPassword($username, $password) == 1)
  {
    print "Login Successful";
  }
  else
  {
    print "Login Failed - incorrect password";
  }
}
else
{
  print "Login Failed - unknown username";
}

In the above code, there are different messages for when an incorrect username is supplied, versus when the username is correct but the password is wrong. This difference enables a potential attacker to understand the state of the login function, and could allow an attacker to discover a valid username by trying different values until the incorrect password message is returned. In essence, this makes it easier for an attacker to obtain half of the necessary authentication credentials.

While this type of information may be helpful to a user, it is also useful to a potential attacker. In the above example, the message for both failed cases should be the same, such as:

"Login Failed - incorrect username or password"

Example Two

This code tries to open a database connection, and prints any exceptions that occur.

try {
  openDbConnection();
}
//print exception message that includes exception message and configuration file location
catch (Exception $e) {
  echo 'Caught exception: ', $e->getMessage(), '\n';
  echo 'Check credentials in config file at: ', $Mysql_config_location, '\n';
}

If an exception occurs, the printed message exposes the location of the configuration file the script is using. An attacker can use this information to target the configuration file (perhaps exploiting a Path Traversal weakness). If the file can be read, the attacker could gain credentials for accessing the database. The attacker may also be able to replace the file with a malicious one, causing the application to use an arbitrary database.

Example Three

In the example below, the method getUserBankAccount retrieves a bank account object from a database using the supplied username and account number to query the database. If an SQLException is raised when querying the database, an error message is created and output to a log file.

public BankAccount getUserBankAccount(String username, String accountNumber) {

  BankAccount userAccount = null;
  String query = null;
  try {
    if (isAuthorizedUser(username)) {
      query = "SELECT * FROM accounts WHERE owner = "
      + username + " AND accountID = " + accountNumber;
      DatabaseManager dbManager = new DatabaseManager();
      Connection conn = dbManager.getConnection();
      Statement stmt = conn.createStatement();
      ResultSet queryResult = stmt.executeQuery(query);
      userAccount = (BankAccount)queryResult.getObject(accountNumber);
    }
  } catch (SQLException ex) {
    String logMessage = "Unable to retrieve account information from database,\nquery: " + query;
    Logger.getLogger(BankManager.class.getName()).log(Level.SEVERE, logMessage, ex);
  }
  return userAccount;

}

The error message that is created includes information about the database query that may contain sensitive information about the database or query logic. In this case, the error message will expose the table name and column names used in the database. This data could be used to simplify other attacks, such as SQL injection (CWE-89) to directly access the database.

Example Four

This code stores location information about the current user:

locationClient = new LocationClient(this, this, this);
locationClient.connect();
currentUser.setLocation(locationClient.getLastLocation());
...

catch (Exception e) {
  AlertDialog.Builder builder = new AlertDialog.Builder(this);
  builder.setMessage("Sorry, this application has experienced an error.");
  AlertDialog alert = builder.create();
  alert.show();
  Log.e("ExampleActivity", "Caught exception: " + e + " While on User:" + User.toString());
}

When the application encounters an exception it will write the user object to the log. Because the user object contains location information, the user's location is also written to the log.

Example Five

The following is an actual MySQL error statement:

Warning: mysql_pconnect(): Access denied for user: 'root@localhost' (Using password: N1nj4) in /usr/local/www/wi-data/includes/database.inc on line 4

The error clearly exposes the database credentials.

Example Six

This code displays some information on a web page.

Social Security Number: <%= ssn %></br>Credit Card Number: <%= ccn %>

The code displays a user's credit card and social security numbers, even though they aren't absolutely necessary.

Example Seven

The following program changes its behavior based on a debug flag.

<% if (Boolean.getBoolean("debugEnabled")) {

  %>
  User account number: <%= acctNo %>
  <%
  } %>

The code writes sensitive debug information to the client browser if the "debugEnabled" flag is set to true .

Example Eight

This code uses location to determine the user's current US State location.

First the application must declare that it requires the ACCESS_FINE_LOCATION permission in the application's manifest.xml:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

During execution, a call to getLastLocation() will return a location based on the application's location permissions. In this case the application has permission for the most accurate location possible:

locationClient = new LocationClient(this, this, this);
locationClient.connect();
Location userCurrLocation;
userCurrLocation = locationClient.getLastLocation();
deriveStateFromCoords(userCurrLocation);

While the application needs this information, it does not need to use the ACCESS_FINE_LOCATION permission, as the ACCESS_COARSE_LOCATION permission will be sufficient to identify which US state the user is in.

See Also

SFP Secondary Cluster: Exposed Data

This category identifies Software Fault Patterns (SFPs) within the Exposed Data cluster (SFP23).

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses

CWE entries in this view are listed in the 2020 CWE Top 25 Most Dangerous Software Weaknesses.

Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors

CWE entries in this view are listed in the 2019 CWE Top 25 Most Dangerous Software Errors.


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