Damn Vulnerable Linux (DVL) is everything a good Linux distribution isn’t. Its developers have spent hours stuffing it with broken, ill-configured, outdated, and exploitable software that makes it vulnerable to attacks.
DVL isn’t built to run on your desktop — it’s a learning tool for security students. DVL is a live CD available as a 150MB ISO.
It’s based on the popular mini-Linux distribution Damn Small Linux (DSL), not only for its minimal size, but also for the fact that DSL uses a 2.4 kernel, which makes it easier to offer vulnerable elements that might not work under the 2.6 kernel.
It contains older, easily breakable versions of Apache, MySQL, PHP, and FTP and SSH daemons, as well as several tools available to help you compile, debug, and break applications running on these services, including GCC, GDB, NASM, strace, ELF Shell, DDD, LDasm, LIDa, and more.
DVL was initiated by Thorsten Schneider of the International Institute for Training, Assessment, and Certification (IITAC) and Secure Software Engineering (S�e) in cooperation with Kryshaam from the French Reverse Engineering Team. «The main idea behind DVL,» says Schneider, «was to build up a training system that I could use for my university lectures.» His goal was to design a Linux system that was as vulnerable as possible, to teach topics such as reverse code engineering, buffer overflows, shellcode development, Web exploitation, and SQL injection.
SQL injection is a common web application attack that focuses on the database backend.
WebGoat is a deliberately insecure J2EE web application maintained by OWASP designed to teach web application security lessons.
1. Prerequisite
Login to your DVL VM, as username root and password toor, unless you changed it to something else.
For those of you that are not part of this class, this is a Damn Vulnerable Linux distribution.
Type : startx
2. Start WebGoat
Start up WebGoat’s Web Server.
Damn Vulnerable Linux —> Training Material —> Web Exploitation —> WebGoat —> Start WebGoat Port 80
You well see that a shell started for WebGoat.
Notice that you will use the following information in step 3.
Link: http://127.0.0.1/WebGoat/attack
Username: guest
Password: guest
Bring up a FireFox Browser on your DVL machine.
Paste in the below WebGoat address
Note
Link: http://127.0.0.1/WebGoat/attack
Username: guest
Password: Guest
Start WebGoat (See Below)
Click on Injection Flaws (See Below)
Click on String SQL Injection (See Below)
Click on Restart this Lesson (See Below)
Enter «Smith» into the textbox and click on Go!
Note: This is how the query is meant to work as designed.
SELECT * FROM user_data WHERE last_name = ?
user_data is a database tablename.
last_name is a column in the tablename called user_data.
Click on Restart this Lesson (See Below)
Now let’s start a popular injection technique.
In the text box enter the following string, %‘ or ‘0’=’0
Click Go!
How does this work?
The «?» in the statement SELECT * FROM user_data WHERE last_name = ?, is the text that gets entered into the text box.
So, if you enter in Smith, the statement that gets executed will look like
SELECT * FROM user_data WHERE last_name = ‘Smith’.
In our case we are entering the string [ %‘ or ‘0’=’0 ], which results in the statement
SELECT * FROM user_data WHERE last_name = ‘ %‘ or ‘0’=’0 ‘
Which mean, show me everything that is either equal to a wild card or is not equal to a wild card.
‘ or 0=0 —, » or 0=0 —, or 0=0 —, ‘ or 0=0 #, » or 0=0 #, or 0=0 #, ‘ or ‘x’=’x, » or «x»=»x, ‘) or (‘x’=’x, ‘ or 1=1—, » or 1=1—, or 1=1—, ‘ or a=a—, » or «a»=»a, ‘) or (‘a’=’a, «) or («a»=»a, hi» or «a»=»a, hi» or 1=1 —, hi’ or 1=1 —, hi’ or ‘a’=’a, hi’) or (‘a’=’a and hi») or («a»=»a
Damn Vulnerable Linux (DVL) is everything a good Linux distribution isn’t. Its developers have spent hours stuffing it with broken, ill-configured, outdated, and exploitable software that makes it vulnerable to attacks.
DVL isn’t built to run on your desktop — it’s a learning tool for security students. DVL is a live CD available as a 150MB ISO.
It’s based on the popular mini-Linux distribution Damn Small Linux (DSL), not only for its minimal size, but also for the fact that DSL uses a 2.4 kernel, which makes it easier to offer vulnerable elements that might not work under the 2.6 kernel.
It contains older, easily breakable versions of Apache, MySQL, PHP, and FTP and SSH daemons, as well as several tools available to help you compile, debug, and break applications running on these services, including GCC, GDB, NASM, strace, ELF Shell, DDD, LDasm, LIDa, and more.
DVL was initiated by Thorsten Schneider of the International Institute for Training, Assessment, and Certification (IITAC) and Secure Software Engineering (S�e) in cooperation with Kryshaam from the French Reverse Engineering Team. «The main idea behind DVL,» says Schneider, «was to build up a training system that I could use for my university lectures.» His goal was to design a Linux system that was as vulnerable as possible, to teach topics such as reverse code engineering, buffer overflows, shellcode development, Web exploitation, and SQL injection.
You need to have virtualization software that allows you to create operating system images using either an ISO or installation CD. For this «how to», I will be using VMware Workstation. However, you can also use other popular tools, such as, VirtualBox.
Click Save
Save to C:\VMware ISO’s\DVL\
In my case, I save it to an external hard drive, hence Hard Drive 2 (E:)
3. Create VMware Image
Click on New Virtual Machine.
Bring up a FireFox Browser on your DVL machine.
Select Install disc image file (iso)
Select the Browse Button
Navigate to where you save the DVL iso.
In my case, the iso was saved to E:\VMware ISO’s\DVL\
Select DVL iso and click open
Select Next
Select the Linux OS, and Other Linux 2.6.x kernel
Naming and Saving Location
Virtual machine name: DVL
Location: In my case, I save it to my external hard drive at E:\VMware
Specify Disk Capacity
Click on the Customize Hardware.
Select Memory
Increase the memory from 256 MB to 512 MB.
Click OK.
Click Finish
Press Enter when you see «boot: »
3. Login to DVL
Credentials (See Below)
Login: root
Password: toor
3. Partition the disk
Determine what disk to format
Command : fdisk -l
Note : In my case, the disk is named /dev/sda
Select disk to be partitioned
Command : fdisk /dev/sda
Input : m
View the partition table
Select «p»
Note: There is 1044 cylinders
Add a new partition
Select «n»
Select «p»
Select «1»
Select the maximum amount of cylinders 1044.
View newly created partition
Select «p»
Note: Previously when «p» was selected there was not a partition listed.
Exit out of fdisk
Select «q»
4. Format the partition
Format the partition on /dev/sda
Command : mkfs.ext3 /dev/sda
Proceed : y
Change Language to English (See Below)
Right Click on DE and click on Configure
Highlight Germany, Click on Remove.
Highlight Italy, Click on Remove.
Only U.S. English should be left.
Click Apply
Click OK
Start the backlash installer
Configure installer as seen below
Note: If the installer completes in a few seconds, then the installer actually failed. The installer should take 5 to 10 minutes to complete. You should see messages like copying /opt with the status bar inching slowly forward.
Click the close button, when you see a status message of «All done! click Close button» and a status bar of 100% complete
