In NCL, you almost never really need to use brute-force password attacks. The most important skill is using the correct wordlist. Now usually, a dictionary attack is sufficient. Occasionally, you will need to use the same wordlist with additional attack parameters to run a hybrid attack.
While not all database password cracking challenges are this easy, you should have enough foundational knowledge to do fairly well. I fully expect you to get all the answers for the Easy and Medium challenges from this guide alone!
Hackers often find fascinating files in the most ordinary of places, one of those being FTP servers. Sometimes, luck will prevail, and anonymous logins will be enabled, meaning anyone can just log in. But more often than not, a valid username and password will be required. But there are several methods to brute-force FTP credentials and gain server access.
File Transfer Protocol is a network protocol used to transfer files. It uses a client-server model in which users can connect to a server using an FTP client. Authentication takes place with a username and password, typically transmitted in plaintext, but can also support anonymous logins if available.
Next, let's create two text files, one for usernames and one for passwords. In a real engagement, we'd want to use files with much larger data sets, but for demonstration purposes, we'll keep these short to speed up the whole process.
We can use the -U flag to set the file containing usernames, and the -P flag to set the file containing passwords. Then, specify the service (FTP) followed by the IP address of our target:
We can see it discovered credentials for user and ftp; the multiple hits are because anonymous logins are allowed for that user, making any password a valid password.
The biggest thing to keep in mind is that we need to set variables for the username and password files. We can accomplish that by setting user to FILE0 and password to FILE1. Next, we simply set the files to the appropriate number. Don't forget to set the host, then we're ready to go:
Using a service like Fail2ban alongside proper firewall rules will also drastically cut down the likelihood of compromise. And like anything else, using strong passwords that are difficult to crack will dissuade all but the most determined attackers.
Today, we explored FTP and how to brute-force credentials using a variety of tools. We covered Ncrack, Medusa, Hydra, Patator, and Metasploit, and we touched on some ways to prevent these types of attacks. FTP might seem like a boring target, but its prevalence makes it worth knowing how to attack.
A brief note - this article is about the theory of how to crack passwords. Understanding how cybercriminals execute attacks is extremely important for understanding how to secure systems against those types of attacks.
This can be done either online (so in real-time, by continually trying different username/password combinations on accounts like social media or banking sites) or offline (for example if you've obtained a set of hashed passwords and are trying to crack them offline).
Offline isn't always possible (it can be difficult to obtain a set of hashed passwords), but it is much less noisy. This is because a security team will probably notice many, many failed login accounts from the same account, but if you can crack the password offline, you won't have a record of failed login attempts.
For example, if you know that someone is using a 5 character long password, composed only of lowercase letters, the total number of possible passwords is 26^5 (26 possible letters to choose from for the first letter, 26 possible choices for the second letter, etc.), or 11,881,376 possible combinations.
When you add in uppercase letters, special characters, and numbers, this gets even more difficult and time consuming to crack. The more possible passwords there are, the harder it is for someone to successfully login with a brute force attack.
This type of attack can be defended against in a couple of different ways. First, you can use sufficiently long, complex passwords (at least 15 characters). You can also use unique passwords for each account (use a password manager!) to reduce the danger from data breaches.
But if the password is sufficiently complex (for example 1098324ukjbfnsdfsnej) and doesn't appear in the 'dictionary' (the precompiled list of combinations you're working from), the attack won't work.
A hacker might also use this type of attack when they know or guess a part of the password (for example, a dog's name, children's birthdays, or an anniversary - information a hacker can find on social media pages or other open source resources).
Whereas the attacks above require trying repeatedly to login, if you have a list of hashed passwords, you can try cracking them on your machine, without setting off alerts generated by repeated failed login attempts. Then you only try logging in once, after you've successfully cracked the password (and therefore there's no failed login attempt).
The most important thing to remember about hacking is that no one wants to do more work than they have to do. For example, brute forcing hashes can be extremely time consuming and difficult. If there's an easier way to get your password, that's probably what a nefarious actor will try first.
For this, the hacker needs to have the target's username and password already. With that, they can send out an email to their victim, with a Google verification code request that was sent to the target's number. Once the target sends the code, the attacker can easily bypass 2FA.
Upon entering the code, the user would see the password reset form. If they did reset, the hackers were given full access to their accounts.. Since the Google spoof email looked like a legitimate email from Google, few who got it looked at it twice.
Having 2FA protection is way better than not having just a username and password to protect your phone or other devices, but it's still not 100% secure. As you can see, it is possible to bypass Google 2-step verification.
Everyperson who uses a Unix computer should have her ownaccount. An account is identified by auserID number (UID) that is associated with one or moreusernames (also known as accountnames ).Traditionally, each account also has a secret passwordassociated with it to prevent unauthorized use. You needto know both your username and your password to log into a Unixsystem.
The username is an identifier: it tells the computer who you are. Incontrast, a password is an authenticator: youuse it to prove to the operating system that you are who you claim tobe. A single person can have more than one Unix account on the samecomputer. In this case, each account would have its own username.
Standard Unix usernames may be between one and eight characters long,although many Unix systems today allow usernames that are longer.Within a single Unix computer, usernames must be unique: no two userscan have the same one. (If two people did have the same username on asingle system, then they would really be sharing the same account.)Traditionally, Unix passwords were also between one and eightcharacters long, although most Unix systems now allow longerpasswords as well. Longer passwords are generally more secure becausethey are harder to guess. More than one user can theoretically havethe same password, although if they do, that usually indicates thatboth users have picked a bad password.
Some versions of Unix have problems with usernames that do not startwith a lowercase letter or that contain special characters such aspunctuation or controlcharacters. Usernames containing certain unusual characters will alsocause problems for various application programs, including somenetwork mail programs. For this reason, many sites allow onlyusernames that contain lowercase letters and numbers and furtherrequire that all usernames start with a letter.
None of these systems is foolproof. For example, by eavesdropping onyour terminal line, somebody can learn your password. By attackingyou at gunpoint, somebody can steal your card key. And if yourattacker has a knife, you might even lose your finger! In general,the more trustworthy the form of authentication, the more aggressivean attacker must be to compromise it. In the past, the mosttrustworthy authentication techniques have also been the mostdifficult to use, although this is slowly changing.
Passwords are the simplest form ofauthentication: they are a secret that you share with the computer.When you log in, you type your password to prove to the computer thatyou are who you claim to be. The computer ensures that the passwordyou type matches the account that you have specified. If it matches,you are allowed to proceed.
Traditionally desktop personal computers running the Windows orMacintosh operating systems, handheld computers, and personalorganizers did not require that users authenticate themselves beforethe computer provided the requested information. The fact that thesecomputers employed no passwords or other authentication techniquesmade them easier to use.
Whenyou log in, you tell the computer who you are by typing your usernameat the login prompt (the identification step).You then type your password (in response to the password prompt) toauthenticate that you are who you claim to be.For example:
On some versions of Unix, if somebodytries to log into an account and supplies an invalid password severaltimes in succession, that account will become locked. A lockedaccount can be unlocked only by the system administrator. Locking hasthree functions:
Youcan change your password with the Unixpasswd command. You will first be asked totype your old password, then a new one. By asking you to type yourold password first, passwd prevents somebodyfrom walking up to a terminal that you left yourself logged into andthen changing your password without your knowledge. 2b1af7f3a8