Common Attack Pattern Enumeration and Classification
A Community Resource for Identifying and Understanding Attacks
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.
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.
Skill or Knowledge Level: Low
A variety of password cracking tools and dictionaries are available to launch this type of an attack.
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.
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.
Employ IP spoofing to make it seem like login attempts are coming from different machines.
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-02.
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