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Many applications need to handle sensitive data either in memory or on disk. If this sensitive data is not protected properly, it might lead to loss of secrecy or integrity of the data. It is very difficult (or expensive) to completely secure all the sensitive data. Users tend to use the same passwords everywhere. So even if your program is a simple game which game that stores the user's profile information and requires the user to enter a password, the user might choose the same password he uses for his or she uses for an online bank account for your game program. Now the user's bank account is only as secure as your program enables it to be.

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Do not hard code sensitive data in programs.

This is considered very bad programming practice because it enforces the requirement of the development environment to be secureSee MSC41-C. Never hard code sensitive information for details.

Disable memory dumps.

Memory dumps are automatically created when your program crashes. These memory dumps  They can contain information stored in any part of program memory. Therefore, memory dumps should be disabled before an application is shipped to users. See recommendation MEM06-C. Ensure that sensitive data is not written out to disk for details.

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Sensitive data that is stored in memory can get written to disk when a page is swapped out of the physical memory. (See next point for details with respect to details about keeping sensitive data on disk.) You may be able to "lock" your data to keep it from swapping out. Your program will generally need administrative privileges to do this so successfully, but it never hurts to try. See recommendation MEM06-C. Ensure that sensitive data is not written out to disk for details.

Do not store sensitive data in plaintext (either on disk or in memory).

See recommendation MEM06-C. Ensure that sensitive data is not written out to disk.

While using a password, consider storing its hash instead of plaintext. Use the hash for comparisons and other purposes. The following code [Viega 2001] illustrates this:

int validate(char *username) {
  char *password;
  char *checksum;
  password = read_password();
  checksum = compute_checksum(password);
  erase(password);  /* securelySecurely erase password */
  return !strcmp(checksum, get_stored_checksum(username));
}

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1. If encrypting or hashing sensitive data, do not implement your own encryption functions (or library). Use proven secure crypto libraries, which have been extensively tested for security.
2. If using standard crypto libraries, be aware that there are they have certain requirements (documented with the library) for the key sizes and other properties. Choose keys satisfying that satisfy these conditions.
3. Do not store the encryption keys (you can derive the key from the hash of the user's password or any other cryptographic mechanism, provided the above condition holds). If the key is to be stored, store it securely.

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1. Be aware of compiler optimization when erasing memory. (See recommendation MSC06-C. Be aware Beware of compiler optimization when dealing with sensitive dataoptimizations.)
2. Use secure erase methods specified in US U.S. Department of Defense Standard 5220 [DOD 5220] or Peter Gutmann's paper [Gutmann 1996].

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If sensitive data is not handled correctly in a program, an attacker can gain access to it.

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Automated Detection

Related Guidelines

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Related Guidelines

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Bibliography

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