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Hard coding sensitive information, such as passwords or encryption keys can expose the information to attackers. Anyone who has access to the executable or dynamic library files can examine them for strings or other critical data, revealing the sensitive information. Leaking data protected by International Traffic in Arms Regulations (ITAR) or the Health Insurance Portability and Accountability Act (HIPAA) can also have legal consequences. Consequently, programs must not hard code sensitive information.

Hard coding sensitive information also increases the need to manage and accommodate changes to the code. For example, changing a hard-coded password in a deployed program may require distribution of a patch [Chess 2007].

Noncompliant Code Example (Hard-Coded Database Password)

The user name and password fields in the SQL connection request are hard coded in this noncompliant code example:This noncompliant code example must authenticate to a remote service with a code, using the authenticate() function declared below. It passes the authentication code to this function as a string literal.

/* Returns nonzero if authenticated */
int authenticate(const char* code);

int main() public final Connection getConnection() throws SQLException {
  return DriverManager.getConnection(
  if (!authenticate("correct code")) {
    "jdbc:mysql://localhost/dbName", 
      "username", "password");
}

Note that the one- and two-argument java.sql.DriverManager.getConnection() methods can also be used incorrectly.

Compliant Solution

printf("Authentication error\n");
    return -1;
  }

  printf("Authentication successful\n");
  // ...Work with system...
  return 0;
}

The authentication code exists in the program's binary executable and can be easily discovered.

Implementation Details (Unix)

Many Unix platforms provide a strings utility that prints out all of the ASCII strings in a binary file. Here is the output of running strings on this program, on an Ubuntu 16.04 platform:

% strings a.out
...
AUATL
[]A\A]A^A_
correct code
Authentication error
Authentication successful
...
%

Compliant Solution (C23, memset_explicit())

This compliant solution requires the user to supply the authentication code, and securely erases it when done, using memset_explicit().This compliant solution reads the user name and password from a configuration file located in a secure directory:

public final Connection getConnection() throws SQLException {
  String username;
  String password;
  // Username and password are read at runtime from a secure config file
  return DriverManager.getConnection(
      "jdbc:mysql://localhost/dbName", username, password);
}

It is also permissible to prompt the user for the user name and password at runtime.

/* Returns nonzero if authenticated */
int authenticate(const char* code);

int main() {
#define CODE_LEN 50
  char code[CODE_LEN];
  printf("Please enter your authentication code:\n");
  fgets(code, sizeof(code), stdin);
  int flag = authenticate(code);
  memset_explicit(code, 0, sizeof(code));
  if (!flag) {
    printf("Access denied\n");
    return -1;
  }
  printf("Access granted\n");
  // ...Work with system...
  return 0;
}

Alternatively, the program could read the authentication code from a file, letting file system security protect the file and the code from untrusted users.When possible, sensitive information such as passwords should be stored in character arrays rather than strings because the Java Virtual Machine may retain strings long after they are no longer needed. However, this example uses strings because DriverManager.getConnection() requires them.

Risk Assessment

Hard coding sensitive information exposes that information to attackers. The severity of this rule can vary depending on the kind of information that is disclosed. Frequently, the information disclosed is password or key information, which can lead to remote exploitation. Consequently, a high severity rating is given but may be adjusted downwards according to the nature of the sensitive data. 

Automated Detection

Related Guidelines

Bibliography

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MSC40-C. Do not violate constraints Rule 48. Miscellaneous (MSC) Rule 50. POSIX (POS)