The product performs a comparison that only examines a portion of a factor before determining whether there is a match, such as a substring, leading to resultant weaknesses.
For example, an attacker might succeed in authentication by providing a small password that matches the associated portion of the larger, correct password.
Threat Mapped score: 3.0
Industry: Finiancial
Threat priority: P2 - Serious (High)
CVE: CVE-2014-6394
Product does not prevent access to restricted directories due to partial string comparison with a public directory
CVE: CVE-2004-1012
Argument parser of an IMAP server treats a partial command "body[p" as if it is "body.peek", leading to index error and out-of-bounds corruption.
CVE: CVE-2004-0765
Web browser only checks the hostname portion of a certificate when the hostname portion of the URI is not a fully qualified domain name (FQDN), which allows remote attackers to spoof trusted certificates.
CVE: CVE-2002-1374
One-character password by attacker checks only against first character of real password.
CVE: CVE-2000-0979
One-character password by attacker checks only against first character of real password.
N/A
N/A
| Phase | Note |
|---|---|
| Implementation | N/A |
Intro: This example defines a fixed username and password. The AuthenticateUser() function is intended to accept a username and a password from an untrusted user, and check to ensure that it matches the username and password. If the username and password match, AuthenticateUser() is intended to indicate that authentication succeeded.
Body: In AuthenticateUser(), the strncmp() call uses the string length of an attacker-provided inPass parameter in order to determine how many characters to check in the password. So, if the attacker only provides a password of length 1, the check will only examine the first byte of the application's password before determining success.
/* Ignore CWE-259 (hard-coded password) and CWE-309 (use of password system for authentication) for this example. */ char *username = "admin"; char *pass = "password"; int AuthenticateUser(char *inUser, char *inPass) { if (strncmp(username, inUser, strlen(inUser))) { logEvent("Auth failure of username using strlen of inUser"); return(AUTH_FAIL); } if (! strncmp(pass, inPass, strlen(inPass))) { logEvent("Auth success of password using strlen of inUser"); return(AUTH_SUCCESS); } else { logEvent("Auth fail of password using sizeof"); return(AUTH_FAIL); } } int main (int argc, char **argv) { int authResult; if (argc < 3) { ExitError("Usage: Provide a username and password"); } authResult = AuthenticateUser(argv[1], argv[2]); if (authResult == AUTH_SUCCESS) { DoAuthenticatedTask(argv[1]); } else { ExitError("Authentication failed"); } }