CWE-307: Improper Restriction of Excessive Authentication Attempts
Improper Restriction of Excessive Authentication Attempts
Weakness ID: 307 (Weakness Base)
Status: Draft
Description
Description Summary
The software does not implement sufficient measures to prevent multiple failed authentication attempts within in a short time frame, making it more susceptible to brute force attacks.
Time of Introduction
Architecture and Design
Applicable Platforms
Languages
Language-independent
Common Consequences
Scope
Effect
Access Control
Technical Impact: Bypass protection
mechanism
An attacker could perform an arbitrary number of authentication
attempts using different passwords, and eventually gain access to the
targeted account.
Demonstrative Examples
Example 1
In January 2009, an attacker was able to gain administrator access
to a Twitter server because the server did not restrict the number of login
attempts. The attacker targeted a member of Twitter's support team and was
able to successfully guess the member's password using a brute force attack
by guessing a large number of common words. Once the attacker gained access
as the member of the support staff, he used the administrator panel to gain
access to 33 accounts that belonged to celebrities and politicians.
Ultimately, fake Twitter messages were sent that appeared to come from the
compromised accounts.
However, there is no limit on parallel connections, so this does not
increase the amount of time an attacker needs to complete an
attack.
Example 4
In the following C/C++ example the validateUser method opens a
socket connection, reads a username and password from the socket and
attempts to authenticate the username and password.
(Bad Code)
Example Languages: C and C++
int validateUser(char *host, int port)
{
int socket = openSocketConnection(host, port);
if (socket < 0) {
printf("Unable to open socket connection");
return(FAIL);
}
int isValidUser = 0;
char username[USERNAME_SIZE];
char password[PASSWORD_SIZE];
while (isValidUser == 0) {
if (getNextMessage(socket, username, USERNAME_SIZE)
> 0) {
if (getNextMessage(socket, password, PASSWORD_SIZE)
> 0) {
The validateUser method will continuously check for a valid username
and password without any restriction on the number of authentication
attempts made. The method should limit the number of authentication
attempts made to prevent brute force attacks as in the following example
code.
(Good Code)
Example Languages: C and C++
int validateUser(char *host, int port)
{
...
int count = 0;
while ((isValidUser == 0) && (count <
MAX_ATTEMPTS)) {
if (getNextMessage(socket, username, USERNAME_SIZE)
> 0) {
if (getNextMessage(socket, password, PASSWORD_SIZE)
> 0) {
Description
