Before attacking any website, it's critical for any white hat hacker or pentester to perform good reconnaissance. Trying various attacks without first finding which attacks the site is vulnerable to is pure foolishness. A few minutes of recon can save you hours on a hack and make the job a lot easier.
There are a number of apps that can find vulnerabilities in websites, but one of the simplest is Nikto, an open-source web server scanner. It examines a website and reports back potential vulnerabilities that it found which could be used to exploit or hack the site. Also, it's one of the most widely used website vulnerabilities tools in the industry, and in many circles, considered the industry standard.
Although this tool is extremely effective, it's not stealthy. Any site with an intrusion-detection system or other security measures in place will detect that you're scanning it. Initially designed for security testing, it was never meant to be stealthy.
Let's fire up Kali and get started with nikto. Once we have Kali up and running, go to Kali Linux -> Vulnerability Analysis -> Misc Scanners -> nikto, like in the screenshot below.
Although there are many options in using nikto, we will limit ourselves here to the basic syntax, such as this:
- nikto -h <IP or hostname>
Let's start with a safe web server on our own network. In this case, I have started the http service on another machine on my network. There is not a website hosted by this machine, just the web server. Let's scan it for vulnerabilities by typing:
- nikto -h 192.168.1.104
Nikto responds with a lot of information, as you can see below.
First, it tells us the server is Apache 2.2.14, probably on Ubuntu. It nailed this info and gives up more information on other potential vulnerabilities on this web server.
Note near the bottom that it identifies some vulnerabilities with the OSVDB prefix. This is the Open Source Vulnerability Database. This is a database maintained of known vulnerabilities at osvdb.org, in addition to other databases I covered, such as SecurityFocus and Microsoft's Technet.
Let's try another site. In an earlier tutorial, we had hacked a web server named webscantest.com. Let's see what nikto can tell us about this site.
- nikto -h webscantest.com
Once again, it identifies the server (Apache) and then proceeds to identify numerous potential vulnerabilities pre-fixed with OSVDB. We can take a look at that website at osvdb.org to learn more about these vulnerabilities.
Now, let's use this site to find information on one of the vulnerabilities identified by nikto as OSVDB-877. We can put that reference number into the search function and it retrieves the following page.
Note, in lower half of this page there are cross-references to the various information sources about this vulnerability, as well as references to tools and filters such as Nikto, Nessus, and Snort.
Let's scan a few more sites and see what it can tell us about these sites. Let's see what we can find out about our own website, wonderhowto.com.
- nikto -h wonderhowto.com
As you can see, it tells us that WonderHowTo is using Microsoft's IIS 8.5 as a web server and then lists numerous potential vulnerabilities.
However, any attempt to exploit the vulnerabilities listed will reveal that they're all false-positives, as WonderHowTo simply returns a harmless 404 page. This is because WonderHowTo is not built on php or asp as the noted exploits expect.
False positives like this can appear because the scan does not actually execute each of the possible vulnerabilities, but rather scans to see if the server responds without error to known exploitable URLs.
Finally, lets point nikto at facebook.com.
- nikto -h facebook.com
As you can see, Facebook is tightly secured with few vulnerabilities. As you can imagine, if Facebook weren't secure, every script-kiddie on the planet would be hacking it to see who his true love is chatting with online.