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On Windows platforms, the BcryptGenRandomBCryptGenRandom() function can be used to generate cryptographically strong random numbers. The Microsoft Developer Network BCryptGenRandom() reference [MSDN] states:

The default random number provider implements an algorithm for generating random numbers that complies with the NIST SP800-90 standard, specifically the CTR_DRBG portion of that standard.

#include <Windows.h>
#include <bcrypt.h>
#include <stdio.h>

#pragma comment(lib, "Bcrypt")

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void func(void) {
  BCRYPT_ALG_HANDLE Prov;
  int Buffer;
  if (!BCRYPT_SUCCESS(
          BCryptOpenAlgorithmProvider(&Prov, BCRYPT_RNG_ALGORITHM,
                                      NULL, 0))) {
    /* handle error */
  }
  if (!BCRYPT_SUCCESS(BCryptGenRandom(Prov, (PUCHAR) (&Buffer),
                                      sizeof(Buffer), 0))) {
    /* handle error */
  }
  printf("Random number: %d\n", Buffer);
  BCryptCloseAlgorithmProvider(Prov, 0);
}

Risk Assessment

The use of the rand() function can result in predictable random numbers.

Automated Detection

Related Vulnerabilities

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

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Key here for mapping notes

CWE-327 and MSC30-C

• CWE-327 forbids “broken or risky cryptographic algorithms” but does not specify what constitutes such an algo.

• Per CERT judgement, rand() qualifies, so:

• CWE-327 = Union( MSC30-C, list) where list =

• Invocation of broken/risky crypto algorithms besides rand()

CWE-338 and MSC30-C

CWE-338 = Union( MSC30-C, list) where list =

• Use of a weak PRNG besides standard C rand().

CWE-330 and MSC30-C

Independent( MSC30-C, MSC32-C, CON33-C)

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MSC30-C, MSC32-C and CON33-C are independent, they have no intersections. They each specify distinct errors regarding PRNGs.

CWE-676 and MSC30-C

• Independent( ENV33-C, CON33-C, STR31-C, EXP33-C, MSC30-C, ERR34-C)

• MSC30-C implies that rand() is dangerous.

• CWE-676 = Union( MSC30-C, list) where list =

• Invocation of other dangerous functions, besides rand().

Bibliography

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