How does a Dictionary-based Password Attack attack work?

It typically unfolds over 4 phases. It begins with: [Determine application's/system's password policy] Determine the password policies of the target application/system.

How do you prevent CAPEC-16?

Create a strong password policy and ensure that your system enforces this policy.

What weaknesses does CAPEC-16 target?

CAPEC-16 exploits 7 CWE weaknesses, including 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).

How severe is CAPEC-16?

MITRE rates CAPEC-16 as High severity with medium likelihood of attack.

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Detailed attack pattern

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CAPEC-16: Dictionary-based Password Attack

An attacker tries each of the words in a dictionary as passwords to gain access to the system via some user's account. If the password chosen by the user was a word within the dictionary, this attack will be successful (in the absence of other mitigations). This is a specific instance of the password brute forcing attack pattern. Dictionary Attacks differ from similar attacks such as Password Spraying (CAPEC-565) and Credential Stuffing (CAPEC-600), since they leverage unknown username/password combinations and don't care about inducing account lockouts.

Last updated June 1, 2026

High

Typical severity

Per MITRE

Medium

Likelihood of attack

Per MITRE

7

Related weaknesses

CWEs this targets

Detailed

Abstraction

MITRE classification

Overview

CAPEC-16 (Dictionary-based Password Attack) is a detailed-level attack pattern catalogued by MITRE in the Common Attack Pattern Enumeration and Classification (CAPEC). It describes a recurring method attackers use to exploit software weaknesses.

How the attack works

The phases an attacker typically follows to carry out this attack.

Step 1
Explore
[Determine application's/system's password policy] Determine the password policies of the target application/system.
- Determine minimum and maximum allowed password lengths.
- Determine format of allowed passwords (whether they are required or allowed to contain numbers, special characters, etc., or whether they are allowed to contain words from the dictionary).
- Determine account lockout policy (a strict account lockout policy will prevent brute force attacks).
Step 2
Explore
[Select dictionaries] Pick the dictionaries to be used in the attack (e.g. different languages, specific terminology, etc.)
- Select dictionary based on particular users' preferred languages.
- Select dictionary based on the application/system's supported languages.
Step 3
Explore
[Determine username(s) to target] Determine username(s) whose passwords to crack.
- Obtain username(s) by sniffing network packets.
- Obtain username(s) by querying application/system (e.g. if upon a failed login attempt, the system indicates whether the entered username was valid or not)
- Obtain usernames from filesystem (e.g. list of directories in C:\Documents and Settings\ in Windows, and list in /etc/passwd in UNIX-like systems)
Step 4
Exploit
[Use dictionary to crack passwords.] Use a password cracking tool that will leverage the dictionary to feed passwords to the system and see if they work.
- Try all words in the dictionary, as well as common misspellings of the words as passwords for the chosen username(s).
- Try common combinations of words in the dictionary, as well as common misspellings of the combinations as passwords for the chosen username(s).

What the attacker needs

Prerequisites

The system uses one factor password based authentication.
The system does not have a sound password policy that is being enforced.
The system does not implement an effective password throttling mechanism.

Skills required

Low skill: A variety of password cracking tools and dictionaries are available to launch this type of an attack.

Resources required

A machine with sufficient resources for the job (e.g. CPU, RAM, HD). Applicable dictionaries are required. Also a password cracking tool or a custom script that leverages the dictionary database to launch the attack.

Consequences

What a successful CAPEC-16 attack can achieve.

Gain Privileges

Affects: Confidentiality, Access Control, Authentication

Read Data

Affects: Confidentiality

Modify Data

Affects: Integrity

How to mitigate it

Defenses that reduce the risk of CAPEC-16.

Create a strong password policy and ensure that your system enforces this policy.
Implement an intelligent password throttling mechanism. Care must be taken to assure that these mechanisms do not excessively enable account lockout attacks such as CAPEC-2.
Leverage multi-factor authentication for all authentication services.

How to detect it

Indicators that this attack may be underway.

Many invalid login attempts are coming from the same machine (same IP address) or for the same log in name. The login attempts use passwords that are dictionary words.

Examples

A system user selects the word "treacherous" as their passwords believing that it would be very difficult to guess. The password-based dictionary attack is used to crack this password and gain access to the account.

The Cisco LEAP challenge/response authentication mechanism uses passwords in a way that is susceptible to dictionary attacks, which makes it easier for remote attackers to gain privileges via brute force password guessing attacks. Cisco LEAP is a mutual authentication algorithm that supports dynamic derivation of session keys. With Cisco LEAP, mutual authentication relies on a shared secret, the user's logon password (which is known by the client and the network), and is used to respond to challenges between the user and the Remote Authentication Dial-In User Service (RADIUS) server. Methods exist for someone to write a tool to launch an offline dictionary attack on password-based authentications that leverage Microsoft MS-CHAP, such as Cisco LEAP. The tool leverages large password lists to efficiently launch offline dictionary attacks against LEAP user accounts, collected through passive sniffing or active techniques. See also: CVE-2003-1096

Frequently asked questions

Common questions about CAPEC-16.

What is CAPEC-16?: An attacker tries each of the words in a dictionary as passwords to gain access to the system via some user's account. If the password chosen by the user was a word within the dictionary, this attack will be successful (in the absence of other mitigations). This is a specific instance of the password brute forcing attack pattern. Dictionary Attacks differ from similar attacks such as Password Spraying (CAPEC-565) and Credential Stuffing (CAPEC-600), since they leverage unknown username/password combinations and don't care about inducing account lockouts.
How does a Dictionary-based Password Attack attack work?: It typically unfolds over 4 phases. It begins with: [Determine application's/system's password policy] Determine the password policies of the target application/system.
How do you prevent CAPEC-16?: Create a strong password policy and ensure that your system enforces this policy.
What weaknesses does CAPEC-16 target?: CAPEC-16 exploits 7 CWE weaknesses, including 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).
How severe is CAPEC-16?: MITRE rates CAPEC-16 as High severity with medium likelihood of attack.

References

Attack-pattern data is sourced from the MITRE CAPEC catalog (v3.9). Weakness associations link to the corresponding CWE entries on RadicalNotion.AI.

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