Dictionary-based Password Attack |
| Attack Pattern ID: 16 (Detailed Attack Pattern Completeness: Complete) | Typical Severity: High | Status: Draft |
DescriptionSummary
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.
Attack Execution Flow
Determine application's/system's password policy:
Determine the password policies of the target application/system.
Attack Step Techniques
ID Attack Step Technique Description Environments 1 Determine minimum and maximum allowed password lengths.
env-All2 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).
env-All3 Determine account lockout policy (a strict account lockout policy will prevent brute force attacks).
env-AllIndicators
ID type Indicator Description Environments 1 Positive Passwords are used in the application/system
env-All2 Negative Passwords are not used in the application/system.
env-AllSelect dictionaries:
Pick the dictionaries to be used in the attack (e.g. different languages, specific terminology, etc.)
Attack Step Techniques
ID Attack Step Technique Description Environments 1 Select dictionary based on particular users' preferred languages.
env-All2 Select dictionary based on the application/system's supported languages.
env-AllDetermine username(s) to target:
Determine username(s) whose passwords to crack.
Attack Step Techniques
ID Attack Step Technique Description Environments 1 Obtain username(s) by sniffing network packets.
env-CommProtocol env-Peer2Peer env-ClientServer2 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)
env-All3 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)
env-Embedded env-LocalIndicators
ID type Indicator Description Environments 1 Negative Remote application or system provides no indication regarding whether a given username is valid or not.
env-ClientServer env-Peer2Peer env-Web env-CommProtocolOutcomes
ID type Outcome Description 1 Success At least one valid username found.2 Failure Presence of any valid usernames could not be established.Security Controls
ID type Security Control Description 1 Preventative Do not reveal information regarding validity of particular usernames to users.2 Corrective Lock out accounts whose usernames are suspected to have been compromised.
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.
Attack Step Techniques
ID Attack Step Technique Description Environments 1 Try all words in the dictionary, as well as common misspellings of the words as passwords for the chosen username(s).
env-All2 Try common combinations of words in the dictionary, as well as common misspellings of the combinations as passwords for the chosen username(s).
env-AllIndicators
ID type Indicator Description Environments 1 Negative Application/system does not use password authentication.
env-AllOutcomes
ID type Outcome Description 1 Success Attacker determines correct password for a user ID and obtains access to application or system.2 Failure Attacker is unable to determine correct password for a user ID and obtain access to application or system.Security Controls
ID type Security Control Description 1 Detective Large number of authentication failures in logs.2 Preventative Enforce strict account lockout policies.3 Preventative Enforce strong passwords (having sufficient length and containing mix of lower case and upper case letters, numbers, and special characters)
Attack PrerequisitesThe 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.
Typical Likelihood of ExploitLikelihood: Medium
Methods of Attack- Brute Force
Examples-InstancesDescription
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.
Description
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.
Related Vulnerabilities
CVE-2003-1096
Attacker Skills or Knowledge RequiredSkill or Knowledge Level: Low
A variety of password cracking tools and dictionaries are available to launch this type of an attack.
Resources RequiredA 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.
Indicators-Warnings of AttackMany 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.
Obfuscation TechniquesEmploy IP spoofing to make it seem like login attempts are coming from different machines.
Solutions and MitigationsCreate 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.
Attack Motivation-Consequences- Privilege Escalation
Related Weaknesses Related Attack Patterns| Nature | Type | ID | Name | Description | View(s) this relationship pertains to |
|---|---|---|---|---|---|
| ChildOf |  Attack Pattern | 49 | Password Brute Forcing | Â | Mechanism of Attack1000 |
Purposes- Penetration
CIA Impact Technical Context| Architectural Paradigms | All |
|---|---|
| Frameworks | All |
| Platforms | All |
| Languages | All |
Content History| Submissions | ||||
|---|---|---|---|---|
| Submitter | Organization | Date | ||
| Eugene Lebanidze | Cigital, Inc | 2007-02-26 | ||
| Modifications | |||||
|---|---|---|---|---|---|
| Modifier | Organization | Date | Comments | ||
| Sean Barnum | Cigital, Inc | 2007-03-01 | Review and revision of content | ||
| Richard Struse | VOXEM, Inc | 2007-03-26 | Review and feedback leading to changes in Solutions | ||
| Sean Barnum | Cigital, Inc | 2007-04-13 | Modified pattern content according to review and feedback | ||
| Amit Sethi | Cigital, Inc. | 2007-10-29 | Added extended Attack Execution Flow | ||
