alpine 3.6
access weakness #481


Weakness Breakdown


An access weakness occurs when software does not properly implement permissions that could have unintended consequences if exploited by malicious actors. An example of this weakness is when a default username and password are set by the developer but do not get changed by the system administrator.

Warning code(s):

Ensure that umask is given most restrictive possible setting.

File Name:



The highlighted line of code below is the trigger point of this particular Alpine 3.6 access weakness.

     fprintf(stderr, "dlopen(): %s\n", dlerror());
  signal(SIGABRT, print_diagnostics);

  // Look up public symbols
  int (*pam_sm_authenticate)(pam_handle_t *, int, int, const char **) =
      (int (*)(pam_handle_t *, int, int, const char **))
      dlsym(pam_module, "pam_sm_authenticate");
  assert(pam_sm_authenticate != NULL);

  // Look up private test-only API
  void (*set_time)(time_t t) =
      (void (*)(time_t))dlsym(pam_module, "set_time");
  int (*compute_code)(uint8_t *, int, unsigned long) =
      (int (*)(uint8_t*, int, unsigned long))dlsym(pam_module, "compute_code");

  for (int otp_mode = 0; otp_mode < 8; ++otp_mode) {
    // Create a secret file with a well-known test vector
    char fn[] = "/tmp/.google_authenticator_XXXXXX";
    mode_t orig_umask = umask(S_IRWXG|S_IRWXO); // Only for the current user.
    int fd = mkstemp(fn);
    assert(fd >= 0);
    static const uint8_t secret[] = "2SH3V3GDW7ZNMGYE";
    assert(write(fd, secret, sizeof(secret)-1) == sizeof(secret)-1);
    assert(write(fd, "\n\" TOTP_AUTH", 12) == 12);
    uint8_t binary_secret[sizeof(secret)];
    size_t binary_secret_len = base32_decode(secret, binary_secret,

    // Set up test argc/argv parameters to let the PAM module know where to
    // find our secret file
    const char *targv[] = { malloc(strlen(fn) + 8), NULL, NULL, NULL, NULL };
    strcat(strcpy((char *)targv[0], "secret="), fn);
    int targc;
    int expected_good_prompts_shown;
    int expected_bad_prompts_shown;

    switch (otp_mode) {
    case 0:
      puts("\nRunning tests, querying for verification code");
      conv_mode = TWO_PROMPTS;
      targc = 1;
      expected_good_prompts_shown = expected_bad_prompts_shown = 1;
    case 1: 

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