Hello! Pentesters, this article is about a brute-forcing tool Hydra. Hydra is one of the favourite tools of security researchers and consultants. Being an excellent tool to perform brute force attacks, it provides various other options which can make your attack more intense and easier to gain unauthorised access to the system remotely. In this article, I have discussed each option available in hydra to make brute force attacks in various scenarios.

Table of Contents

• Introduction to Hydra
• To guess password for a specific username
• Brute forcing Username and Password
• Verbose and Debug Mode
• NULL/Same as Login or Reverse login Attempt
• Saving output in disk
• To Resume Brute Force Attack
• Password generating using various set of characters
• To attack on a specific port rather than the default
• Attacking Multiple Hosts
• Using Combo Entries
• Concurrent testing on Multiple Logins
• HTTP Login Form Brute Force
• Service module Usage information
• Attacking on secured service connection
• Proxy Support

Introduction to Hydra

Hydra – a very fast network logon cracker which supports many different services. It is a parallelized login cracker which supports numerous protocols to attack. New modules are easy to add, besides that, it is flexible and very fast. This tool gives researchers and security consultants the possibility to show how easy it would be to gain unauthorized access from a remote to a system.

Currently this tool supports: adam6500, afp, asterisk, cisco, cisco-enable, cvs, firebird, ftp, ftps, http[s]-{head|get|post}, http[s]-{get|post}-form, http-proxy, http-proxy-urlenum, icq, imap[s], irc, ldap2[s], ldap3[-{cram|digest}md5][s], mssql mysql(v4), mysql5, ncp, nntp, oracle, oracle-listener, oracle-sid, pcanywhere, pcnfs, pop3[s], postgres, rdp, radmin2, redis, rexec, rlogin, rpcap, rsh, rtsp, s7-300, sapr3, sip, smb, smtp[s], smtp-enum, snmp, socks5, ssh, sshkey, svn, teamspeak, telnet[s], vmauthd, vnc, xmpp

For most protocols, SSL is supported (e.g., https-get, ftp-SSL, etc.).  If not, all necessary libraries are found during compile time, your available services will be less.  Type “hydra” to see what is available.

To guess Password for specific username

If you have a correct username but want to login without knowing the password, so you can use a list of passwords and brute force on passwords on the host for ftp service.

hydra -l ignite -P pass.txt 192.168.1.141 ftp

Here -l option is for username -P for password lists and host ip address for ftp service.

For login ignite password 123 made success.

To guess username for specific password

You may have a valid password but no idea what username to use. Assume you have a password for specific ftp login. You can brute force the field with correct username wordlists to find the correct. You can use the -L option to specify user wordlists and the -p option to specify a specific password.

hydra -L users.txt -p 123 192.168.1.141 ftp

Here, our wordlist is users.txt for which -L option is used, and password is 123 and for that   -p option is used over ftp.

Brute forcing Username and Password

Now if you don’t have either of username or password, for that you can use a brute force attack on both the parameters username and password with a wordlist of both and you can use -P and -U parameters for that.

hydra -L users.txt -P pass.txt 192.168.1.141 ftp

Users.txt is wordlist for username and pass.txt is wordlist for password and the attack has displayed valid credentials ignite and 123 for the host.

Verbose and Debug Mode

-V option is used for verbose mode, where it will show the login+pass combination for each attempt. Here, I have two wordlists users.txt and pass.txt so the brute force attack was making combinations of each login+password and verbose mode showed all the attempts.

hydra -L users.txt -P pass.txt 192.168.1.141 ftp -V

Here the users.txt has 5 usernames and pass.txt has 7 passwords so the number of attempts was 5*7= 35 as shown in the screenshot.

Now is the -d option used to enable debug mode. It shows the complete detail of the attack with wait time, conwait, socket, PID, RECV  

hydra -l ignite -P pass.txt 192.168.1.141 ftp -d

-d option enabled debug mode which, as shown displayed complete detail of the attack.

NULL/Same as Login or Reverse login Attempt

Hydra has an option -e which will check 3 more passwords while brute-forcing. [n] for null, [s] for same i.e., as same as the username and [r] for reverse i.e., the reverse of username. As shown in the screenshot, while brute-forcing the password field, it will first check with the null option then the same option and after that reverse. And then the list which I have provided.

hydra -L users.txt -P pass.txt 192.168.1.141 ftp -V -e nsr

I have enabled verbose mode also so that we can get detailed information about the attempts made while brute-forcing.   

Saving output in Disk

This tool gives you an option to save the result into the disk. Basically for record maintenance, better readability and future preferences we can save the output of the brute force attack into a file by using the -o parameter.

hydra -L users.txt -P pass.txt 192.168.1.141 ftp -o result.txt

I tried to use this option and got success using the above command where the output is stored in the result.txt file.

hydra -L users.txt -P pass.txt 192.168.1.141 ftp -o result:json

I have used this option to store result in json file format also, this type is a unique thing provided by hydra.

To Resume Brute Force Attack

It may happen sometimes, that attack gets halted/paused accidentally due to some unexpected behaviour by hydra. So, hydra has solved this problem by including the -R option so that you can resume the attack from that position rather than starting from the beginning.

hydra -L users.txt -P pass.txt 192.168.1.141 ftp
hydra -R

First, I started the attack using the first command, then halted the attack by pressing CTRL + C and then by using the second command I resumed the attack. 

Password generating using various set of characters

To generate passwords using various set of characters, you can use -x option. It is used as -x  min:max:charset  where,

Min: specifies minimum number of characters in a password.

Max: specifies the maximum number of characters in password.

Charset: charset can contain 1 for numbers, a for lowercase and A for uppercase characters. Any other character which is added is put to the list.

Let’s consider as example: 1:2:a1%.

The generated passwords will be of length 1 to 2 and contain lowercase letters, numbers and/or percent signs and dots.

hydra -l ignite -x 1:3:1 ftp://192.168.1.141

So, here minimum length of password is 1 and the max length is 3 which will contain numbers and for password 123 it showed success.

To make you understand better I have used -V mode and it has displayed results in detail.

To attack a specific port rather than default

Network admins sometimes change the default port number of some services for security reasons. In the previous commands hydra was making brute force attack on ftp service by just mentioning the service name rather than port, but as mentioned earlier default port gets changed at this time hydra will help you with the -s option. If the service is on a different default port, define it using the -s option.

nmap -sV 192.168.1.141
hydra -L users.txt -P pass.txt 192.168.1.141 ssh -s 2222

So to perform, first I tried running a nmap scan at the host. And the screenshot shows all open ports where ssh is at the 2222 port. So post that I tried executing the hydra command with -s parameter and port number.

I have brute-forced on ssh service mentioning the port number, 2222.

Here it found valid entries with user ignite and password 123.

Attacking Multiple Hosts

As earlier I performed a brute force attack using password file pass.txt and username file users.txt on a single host i.e., 191.168.1.141. But if there are multiple hosts, for that you can use -M with the help of which brute force is happening at multiple hosts.

hydra -L users.txt -P pass.txt -M hosts.txt ftp

First, I have created a new file hosts.txt which contains all the hosts. Then the result is showing 2 valid hosts, username and password with success.

Now in the above command, I have used the -M option for multiple hosts so, it is very time-consuming to display all the attempts taking place while the attack, for that medusa, has provided -F option such that the attack will exit after the first found login/password pair for any host.

hydra -L users.txt -P pass.txt -M hosts.txt ftp -F

Using Combo Entries

This tool gives you a unique parameter -C for using combo entries. First, you need to create a file which has data in the colon-separated “login:pass” format,  and then you can use -C option mentioning the file name and perform a brute force attack instead of using  -L/-P options separately. In this way, the attack can be faster and gives you desired result in lesser time.

cat userpass.txt
hydra -C userpass.txt 192.168.1.141 ftp

So, I have created a userpass.txt file using cat command and entered details in “login:pass” format. Then I used -C option in the hydra command to start the attack.

Concurrent Testing on Multiple Logins

If you want to test multiple logins concurrently, for that you can use -t option by mentioning the number and hence hydra will brute force concurrently.

hydra -L users.txt -P pass.txt 192.168.1.141 ftp -t 3 -V

As shown in the screenshot, three attempts are made concurrently, three passwords are concurrently checking with user ignite at host 192.168.1.141, as you can observe child changes 0, 1,2 that means it is concurrently making three attempts and printed 3 of them simultaneously.

HTTP Login Form Brute Force

The hydra form can be used to carry out a brute force attack on simple web-based login forms that requires username and password variables either by GET or POST request. For testing I used dvwa (damn vulnerable web application) which has login page. This page uses POST method as I am sending some data.

hydra -l admin -P pass.txt 192.168.1.150 http-post-form “/dvwa/login.php:username=^USER^&password=^PASS^&Login=Login:Login failed”

Here I have given the username admin and provided file for passwords and used http-post-form module to perform brute force attack on 192.168.1.150 host.

So, for password: password it gave success and bypassed the login page. Now I had performed brute force on username and password field mentioned having security level as “low”. And by using cookie editor plugin I found out the cookie PHPSESSID and used its value in the command.

hydra 192.168.1.150 -l admin -P ‘pass.txt’ http-get-form “/dvwa/vulnerabilities/brute/:username=^USER^&password=^PASS^&Login=Login:F=Username and/or password incorrect.:H=Cookie:PHPSESSID=13f2650bddf7a9ef68858ceea03c5d; security=low”

I had viewed page source and from that I found out that page uses GET method, and so http-GET-form module as mentioned in above command.

As in the screenshot, the command is successfully executed, and I got the correct username and password.

Service module Usage information

As discussed earlier in the introduction all the supported services by hydra, if you want to check once just type hydra -h and you will get list of services supported by hydra. So, to get the detailed information about the usage hydra provides -U option.

hydra http-get-form -U

Here http-get-form is one of the services supported by hydra and -U option helped to get detailed information.

Attacking on secured service connection

While performing an attack on ftp connection, you just mention the service name along with appropriate options, but if the host has ftp port open and ftp is secured, so if you use

hydra -l ignite -P pass.txt ftp://192.168.1.141

This command will not execute properly and hence 0 valid passwords were found. So in order to perform an attack on a secured ftp connection, then run this command.

hydra -l ignite -P pass.txt ftps://192.168.1.141

And this command worked well and showed 1 valid password found.

This is one way to attack secured ftp, hydra provides one more way to attack secured service.

hydra -l ignite -P pass.txt 192.168.1.141 ftp
hydra -l ignite -P pass.txt 192.168.1.141 ftps

The first did not work as the host 192.168.1.141 has secured ftp, but the second, worked and showed us a valid password found. In this way, you can perform a brute force attacks on hosts which have secured services open.

Proxy Support

Now let’s discuss how hydra attacks on hosts having proxy enabled. I first tried to same command with -l -p parameters on host 192.168.1.141 on ftp service and found that no password was found. Hence, I started an nmap scan for the host and found list of services and ports open. So, at port 1080 a proxy “socks5” was set without any authentication.

Unauthenticated Proxy

Hydra provides two different ways for proxy support. I have tried both the ways. Use screenshots for better understanding. Let’s discuss the first way

1.  Environment Variable

To enable proxy I used this command

export HYDRA_PROXY=socks5://192.168.1.141:1080

And then used the following command and got 1 valid password

hydra -l ignite -P pass.txt 192.168.1.141 ftp

2. Proxychains

I have opened the /etc/proxychains4.conf and added the proxy details with host and port. And then with the help of proxychains brute force is performed

cat /etc/proxychains4.conf

proxychains hydra -l ignite -P pass.txt 192.168.1.141 ftp

Authenticated Proxy

I got the desired password 123 for the host. In the above attack, there was not any authentication enabled. Now I tried on a proxy that has authentication enabled.

1. Proxychains

I tried to brute force the target using proxychains but it was denied because authentication was enabled on the proxy.

proxychains hydra -l ignite -p pass.txt 192.168.1.141 ftp

So, I added the username and password in /etc/proxychains4.conf file

cat /etc/proxychains4.conf

Just observe the screenshot for better understanding. Then with the help of proxychains, I started attacking using the below command

proxychains hydra -l ignite -P pass.txt 192.168.1.141 ftp

Hence, after execution of this command, a valid password was found for the host having proxy enabled.    

2. Environment Variable

export HYDRA_PROXY=socks5://raj:[email protected]:1080

Here “raj” is the username, “1234” is password for the proxy and “192.168.1.141” is the host and “1080” is the port on which the proxy is enabled. After that, I used the command

hydra -l ignite -P pass.txt 192.168.1.141 ftp

And for this, it showed a valid password for the host 192.168.1.141 

Note: For setting up the proxy I took reference from https://www.hackingarticles.in/penetration-testing-lab-setup-microsocks/

Author: Divya Adwani is a researcher and technical writer who is very much keen to learn and enthusiastic to learn ethical hacking Contact here