Fun with VBScript malware

An infinite reboot script and a (somewhat buggy) reverse shell

Contents at a glance

1. Introduction
2. Infinite rebooting
3. Reverse shell
4. Final thoughts
5. Acknowledgments
6. Works cited

Introduction

The Visual Basic Scripting (VBScript) language is a fairly old interpreted language that is a subset of Microsoft’s Visual Basic language. It is mainly used for automating system administration tasks, but it can also be repurposed for malware purposes. In fact, the well-known (in)famous LOVELETTER virus was written in VBScript (Virus Encyclopedia, n.d.).

Here, I am going to discuss a couple of VBScript malware tools that I wrote, and hopefully these can be used as a “springboard” for other penetration testers and security researchers to develop their tools.

Infinite rebooting

I’ll start with a simple script that will cause a computer system to reboot upon logging in. This script will install a batch file that will reboot the computer as the user logs in, and after installation, will launch a “guess my random number” game as to prevent suspicion from the user: