The road to becoming a skilled white hat is paved with many milestones, one of those being learning how to perform a simple Nmap scan. A little further down that road lies more advanced scanning, along with utilizing a powerful feature of Nmap called the Nmap Scripting Engine. Even further down the road is learning how to modify and write scripts for NSE, which is what we'll be doing today.
Nmap is possibly the most widely used security scanner of its kind, in part because of its appearances in films such as The Matrix Reloaded and Live Free or Die Hard. Still, most of Nmap's best features are under-appreciated by hackers and pentesters, one of which will improve one's abilities to quickly identify exploits and vulnerabilities when scanning servers.
Computers all over the world rely on a program called "libssh" to use the SSH communications protocol, which allows trusted users to log in and administer computers remotely. Due to a flaw in libssh, fooling a computer into granting SSH access is as easy as telling it you already have permission. The vulnerability can lead to an attacker gaining complete control over a device.
Nmap is more powerful than you know. With a few scripts, we can extend its functionality beyond a simple port scanner and start to identify details about target servers sysadmins don't want us to know.
The public leaks of NSA tools and information have led to the release of previously secret zero-day exploits such as EternalBlue, which was used in the notorious WannaCry ransomware attack. Despite multiple patches being released, many users have failed to update their systems, so many devices are still vulnerable to these now-public attacks.
In my previous article, we learned how to generate a vulnerable virtual machine using SecGen to safely and legally practice hacking. In this tutorial, we will put it all together, and learn how to actually hack our practice VM. This will provide some insight into the methodology behind an actual attack and demonstrate the proper way to practice on a VM.
Gaining access to a system is always exciting, but where do you go from there? Root or bust. Sure, a compromised host is a great way to run a botnet, or do some other boring, nefarious thing—but as hackers, we want root. We also want to take the easiest path possible, search out low-hanging fruit, and exploit them. SUID programs are the lowest of the low-hanging fruit.
Remember that scene in The Matrix when Trinity uses a realistic Nmap port scan, followed by an actual SSH exploit (long since patched) to break into a power company? Well, believe it or not, but that scene is not far fetched at all.
The already robust and ingenious Nmap tool has received a whole slew of new scanning scripts that can be used to do all sorts of naughty endeavors. Notably, the SQLi module, since it is a necessary evil that we must cover here at Null Byte. This major update is going to fuel today's lesson.