The sys admin's daily grind – Metasploitable

Gone to the Dogs

Article from Issue 172/2015

If you mess around with a pen-testing tool on your own network, you might survive the consequences, but chances are you'll take the prize for outstanding recklessness. Charly has some advice: Use Metasploitable, perhaps the most broken Linux ever.

You've probably heard of the Darwin Awards [1]. This hilarious prize goes to people who improve the quality of the human gene pool by removing their own genes in an outstandingly stupid way. Because of this, almost all Darwin Awards are awarded posthumously – the few exceptions are unappetizing and don't make good family reading material [2].

My favorite award went to two gentlemen who took their off-road vehicle onto a frozen lake to indulge in a spot of dynamite fishing. One of the men set fire to an explosive charge and threw it far away. The men were a bit shocked when their dog cleverly retrieved the dangerous stick.

Given this emergency, they pulled out guns to stop the dog, which promptly hid under the SUV for safety. Needless to say, the dynamite detonated, the car sank, and the blast blew away the clever owners. They lost consciousness and were later found frozen to death. Pity about the dog – respect for the forensic scientist who reconstructed the sequence.

Bad luck stories can also be found on the web. Every administrator can probably relate to a tale of pen-testing tools running amok and suddenly shooting down the main production – preferably instigated by a trainee who wanted to see exactly what this or that metasploit could do.

Attacking your own network is really not necessary because there is an adventure playground waiting out there for you to romp around in safely. It goes by the name Metasploitable, and I think the name says it all. The Linux image is available online [3] and can be started in VMware or VirtualBox. After doing this, you have a huge range of vulnerabilities to attack.

Vulnerabilities En Masse

Some vulnerabilities are only of archaeological interest, such as the broken R services rlogin and rsh, which older readers will remember. Younger readers may only be familiar with SSH and that, too, is a disaster on Metasploitable – not to mention the weak to non-existent default passwords of all kinds of services.

Another group of vulnerabilities involves trojaned services, of which Metasploitable offers a fair number. They arise when someone hacks the download repository of a popular program and replaces the software with malware or a backdoored version. If you install this version on the server, you can soon look forward to unexpected visitors.

An example is the popular FTP daemon, vsftpd. It was once replaced with a version that opened a root shell on port 6200 if users logged on with a smiley after the username (Figure 1).

Figure 1: Smile to gain root – vsftpd 2.3.4 makes it possible.

So, if your trainees want to play pen-tester, give them Metasploitable and disconnect them from the LAN switch. They will be so fascinated with the options that they will not have any time at all for dynamite fishing.

The Author

Charly Kühnast is a Unix operating system administrator at the Data Center in Moers, Germany. His tasks include firewall and DMZ security and availability. He divides his leisure time into hot, wet, and eastern sectors, where he enjoys cooking, freshwater aquariums, and learning Japanese, respectively.

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