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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 that stores the user's profile information and requires the user to enter a password, the user might choose the same password he 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.

There are simple steps you can take to secure sensitive data in your programs.

Prefer the system's authentication dialog (or any other mechanism provided by the OS) for authentication to privileged services.

If you are accessing some privileged service already installed on the system, most likely that service will have some mechanism to take a password from the user. Before asking the user for a user name and password from your application, check if the service itself authenticates the user in some way. If so, let the service handle the authentication because doing so would at least not increase the footprint of the sensitive data.

Do not hard code sensitive data in programs.

See MSC41-C. Never hard code sensitive information for details.

Disable memory dumps.

Memory dumps are automatically created when your program crashes. 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 MEM06-C. Ensure that sensitive data is not written out to disk for details.

Do not store sensitive data beyond its time of use in a program.

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 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 so successfully, but it never hurts to try. See 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 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:

int validate(char *username) {
  char *password;
  char *checksum;
  password = read_password();
  checksum = compute_checksum(password);
  erase(password);  /* Securely erase password */
  return !strcmp(checksum, get_stored_checksum(username));
}
If you must store sensitive data, encrypt it first.
  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 they have certain requirements (documented with the library) for the key sizes and other properties. Choose keys 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.
Securely erase sensitive data from disk and memory.
  1. Be aware of compiler optimization when erasing memory. (See MSC06-C. Beware of compiler optimizations.)
  2. Use secure erase methods specified in U.S. Department of Defense Standard 5220 [DOD 5220] or Peter Gutmann's paper [Gutmann 1996].

Risk Assessment

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

Recommendation

Severity

Likelihood

Remediation Cost

Priority

Level

MSC18-C

Medium

Probable

Medium

P8

L2

Related Vulnerabilities

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

Automated Detection

ToolVersionCheckerDescription
CodeSonar
5.0p0

HARDCODED.AUTH

HARDCODED.KEY

HARDCODED.SALT

MISC.CRYPTO.NOPAD

MISC.PWD.PLAIN

Hardcoded Authentication

Hardcoded Crypto Key

Hardcoded Crypto Salt

Encryption without Padding

Plaintext Storage of Password

Polyspace Bug Finder

R2018a

Sensitive heap memory not cleared before release

Uncleared sensitive data in stack

Unsafe standard encryption function

Constant cipher key

Constant block cipher initialization vector

Predictable cipher key

Predictable block cipher initialization vector

Sensitive data not cleared or released by memory routine

Variable in stack is not cleared and contains sensitive data

Function is not reentrant or uses a risky encryption algorithm

Encryption or decryption key is constant instead of randomized or  generated from a weak random number generator

Initialization vector is constant instead of randomized

Encryption or decryption key is generated from a weak random number generator

Initialization vector is generated from a weak random number generator

Related Guidelines

CERT Oracle Secure Coding Standard for JavaMSC03-J. Never hard code sensitive information
SEI CERT C Coding StandardMSC41-C. Never hard code sensitive information
MITRE CWECWE-259, Use of Hard-coded Password
CWE-261, Weak Cryptography for Passwords
CWE-311, Missing encryption of sensitive data
CWE-319, Cleartext Transmission of Sensitive Information
CWE-321, Use of Hard-coded Cryptographic Key
CWE-326, Inadequate encryption strength
CWE-798, Use of hard-coded credentials

Bibliography



5 Comments

  1. For this part: 

    If you must store sensitive data, encrypt it first.

    I suggest adding reference to CWE 326 as well.

  2. Hi,


    There is a rule for Java which is  MSC03-J. Never hard code sensitive information



    As i know and saw, it is possible to find information since an exe or dll. It is likely more difficult.


    Don't you think we should have the same rule for C ?


    Jérôme

    1. You're right. I've added a C rule: MSC41-C. Never hard code sensitive information, based on the Java rule. Comments welcome.