CAPEC-49
Password Brute Forcing
An adversary tries every possible value for a password until they succeed. A brute force attack, if feasible computationally, will always be successful because it will essentially go through all possible passwords given the alphabet used (lower case letters, upper case letters, numbers, symbols, etc.) and the maximum length of the password.
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A system will be particularly vulnerable to this type of an attack if it does not have a proper enforcement mechanism in place to ensure that passwords selected by users are strong passwords that comply with an adequate password policy. In practice a pure brute force attack on passwords is rarely used, unless the password is suspected to be weak. Other password cracking methods exist that are far more effective (e.g. dictionary attacks, rainbow tables, etc.). Knowing the password policy on the system can make a brute force attack more efficient. For instance, if the policy states that all passwords must be of a certain level, there is no need to check smaller candidates.
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Explain the attack pattern CAPEC-49: Password Brute Forcing: how it unfolds, what it needs and how to prevent and detect it in my systems. Use https://capec.mitre.org/data/definitions/49.html and https://cve.bz/cve/capec/49?via=ask-ai-copy, which lists recent CVEs with the weaknesses it exploits. Cite the sources.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this attack pattern's id and public links.
How the attack unfolds
Explore
The attacker looks for a way in.
[Determine application's/system's password policy] Determine the password policies of the target application/system.
3 techniques
- Determine minimum and maximum allowed password lengths.
- Determine format of allowed passwords (whether they are required or allowed to contain numbers, special characters, etc.).
- Determine account lockout policy (a strict account lockout policy will prevent brute force attacks).
Exploit
They carry out the attack.
[Brute force password] Given the finite space of possible passwords dictated by the password policy determined in the previous step, try all possible passwords for a known user ID until application/system grants access.
2 techniques
- Manually or automatically enter all possible passwords through the application/system's interface. In most systems, start with the shortest and simplest possible passwords, because most users tend to select such passwords if allowed to do so.
- Perform an offline dictionary attack or a rainbow table attack against a known password hash.
Prerequisites
An adversary needs to know a username to target.
The system uses password based authentication as the one factor authentication mechanism.
An application does not have a password throttling mechanism in place. A good password throttling mechanism will make it almost impossible computationally to brute force a password as it may either lock out the user after a certain number of incorrect attempts or introduce time out periods. Both of these would make a brute force attack impractical.
Skills required
- Low skill
A brute force attack is very straightforward. A variety of password cracking tools are widely available.
Resources required
A powerful enough computer for the job with sufficient CPU, RAM and HD. Exact requirements will depend on the size of the brute force job and the time requirement for completion. Some brute forcing jobs may require grid or distributed computing (e.g. DES Challenge).
Signs of an attack
Many incorrect login attempts are detected by the system.
Consequences
| Impact | Affects | Note |
|---|---|---|
| Gain Privileges | Confidentiality, Access Control, Authorization | |
| Read Data | Confidentiality | |
| Modify Data | Integrity |
Mitigations
Implement a password throttling mechanism. This mechanism should take into account both the IP address and the log in name of the user.
Put together a strong password policy and make sure that all user created passwords comply with it. Alternatively automatically generate strong passwords for users.
Passwords need to be recycled to prevent aging, that is every once in a while a new password must be chosen.
Weaknesses it exploits
- CWE-257 Storing Passwords in a Recoverable Format
- CWE-262 Not Using Password Aging
- CWE-263 Password Aging with Long Expiration
- CWE-307 Improper Restriction of Excessive Authentication Attempts
- CWE-308 Use of Single-factor Authentication
- CWE-309 Use of Password System for Primary Authentication
- CWE-521 Weak Password Requirements
- CWE-654 Reliance on a Single Factor in a Security Decision
Recent CVEs with these weaknesses
- 5.4CVE-2026-113968
A logic issue was addressed with improved state management. This issue is fixed in iOS 18.7.12 and iPadOS 18.7.12, iOS 26.7.3 and iPadOS 26.7.3, iOS 27.2.1 and iPadOS 27.2.1, macOS Golden Gate 27.2.1, macOS Sequoia 15.8.3, macOS Tahoe 26.7…
- 5.4CVE-2026-113964
A logic issue was addressed with improved state management. This issue is fixed in iOS 18.7.12 and iPadOS 18.7.12, iOS 26.7.3 and iPadOS 26.7.3, iOS 27.2.1 and iPadOS 27.2.1, macOS Golden Gate 27.2.1, macOS Sequoia 15.8.3, macOS Tahoe 26.7…
- 6.9CVE-2026-112205
WidzialniCMS is vulnerable to Bruteforce Protection Bypass in the login functionality. The cookie-based lockout can be bypassed by omitting the login_count and login_timeout cookies, allowing an unauthenticated attacker to perform an unlim…
- 6.3CVE-2026-124575
A vulnerability was identified in SiteServer SSCMS up to 7.1.3/7.2.1/7.4.0. This issue affects the function LoginController.Submit of the file src/SSCMS.Web/Controllers/Admin/LoginController.Submit.cs of the component Admin-Login CAPTCHA. …
- 9.3CVE-2026-124445
OpenEMR from 7.0.1 before 8.4.0 contains a flaw in src/Common/Auth/OneTimeAuth.php that ignores the enforce_onetime_use and max_access_count flags, never revokes consumed service_auth tokens, and checks login_pin without rate limiting or s…
- 6.0CVE-2026-123521
Vikunja before 2.7.1 contains an improper restriction of excessive authentication attempts vulnerability that allows session holders to brute-force account passwords via unthrottled re-authentication endpoints. Attackers with a stolen sess…
- 8.9CVE-2026-17280
IBM API Connect 10.0.8.0 through 10.0.8.12 and 12.1.0.0 through 12.1.1.2 could allow a remote attacker to perform unauthenticated brute-force attacks to obtain valid credentials due to improper restriction of excessive authentication attem…
- 7.5CVE-2026-68933
Chartbrew is an open-source web application that can connect directly to databases and APIs and use the data to create charts. Prior to 5.2.3, public dashboard passwords were stored in plaintext, accepted through a URL query parameter, and…
The newest records naming one of them. Each weakness's page lists them all.
Related attack patterns
- Part of
- CAPEC-112 Brute Force
- Can lead to
Examples
A system does not enforce a strong password policy and the user picks a five letter password consisting of lo…
A system does not enforce a strong password policy and the user picks a five letter password consisting of lower case English letters only. The system does not implement any password throttling mechanism. Assuming the adversary does not know the length of the users' password, an adversary can brute force this password in maximum 1+26+26^2+26^3+26^4+26^5 = 1 + 26 + 676 + 17576 + 456976 + 11,881,376 = 12,356,631 attempts, and half these tries (6,178,316) on average. Using modern hardware this attack is trivial. If the adversary were to assume that the user password could also contain upper case letters (and it was case sensitive) and/or numbers, than the number of trials would have been larger.
An adversary's job would have most likely been even easier because many users who choose easy to brute force passwords like this are also likely to use a word that can be found in the dictionary. Since there are far fewer valid English words containing up to five letters than 12,356,631, an attack that tries each of the entries in the English dictionary would go even faster.
A weakness exists in the automatic password generation routine of Mailman prior to 2.1.5 that causes only abo…
A weakness exists in the automatic password generation routine of Mailman prior to 2.1.5 that causes only about five million different passwords to be generated. This makes it easy to brute force the password for all users who decided to let Mailman automatically generate their passwords for them. Users who chose their own passwords during the sign up process would not have been affected (assuming that they chose strong passwords). See also: CVE-2004-1143
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