Critical Data Element Declared Public

Description

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 example declares a critical variable public, making it accessible to anyone with access to the object in which it is contained.

public: char* password;

Instead, the critical data should be declared private.

private: char* password;

Even though this example declares the password to be private, there are other possible issues with this implementation, such as the possibility of recovering the password from process memory (CWE-257).

Example Two

The following example shows a basic user account class that includes member variables for the username and password as well as a public constructor for the class and a public method to authorize access to the user account.

#define MAX_PASSWORD_LENGTH 15
#define MAX_USERNAME_LENGTH 15

class UserAccount
{

  public:

    UserAccount(char *username, char *password)
    {
      if ((strlen(username) > MAX_USERNAME_LENGTH) ||
      (strlen(password) > MAX_PASSWORD_LENGTH)) {
        ExitError("Invalid username or password");
      }
      strcpy(this->username, username);
      strcpy(this->password, password);
    }



  int authorizeAccess(char *username, char *password)
  {

    if ((strlen(username) > MAX_USERNAME_LENGTH) ||
    (strlen(password) > MAX_PASSWORD_LENGTH)) {
      ExitError("Invalid username or password");
    }
    // if the username and password in the input parameters are equal to

    // the username and password of this account class then authorize access
    if (strcmp(this->username, username) ||
    strcmp(this->password, password))
      return 0;

    // otherwise do not authorize access
    else
      return 1;


  }

  char username[MAX_USERNAME_LENGTH+1];
  char password[MAX_PASSWORD_LENGTH+1];

};

However, the member variables username and password are declared public and therefore will allow access and changes to the member variables to anyone with access to the object. These member variables should be declared private as shown below to prevent unauthorized access and changes.

class UserAccount
{
public:
  ...


private:
  char username[MAX_USERNAME_LENGTH+1];
  char password[MAX_PASSWORD_LENGTH+1];
};

See Also