Use Their Machines Against Them: Loading Code with a Copier

Presented at DEF CON 24 (2016), Aug. 7, 2016, 11 a.m. (60 minutes)

We've all worked on ‘closed systems’ with little to no direct Internet access. And we've all struggled with the limitations those systems put on us in the form of available tools or software we want to use. I didn't like struggling, so I came up with a method to load whatever I wanted on to a closed system without triggering any common security alerts. To do this I had to avoid accessing the Internet or using mag media. In the end all I needed was an office multi-function machine and Excel. It's all any insider needs.

For my presentation and demo, I'll show you how I delivered a select group of PowerSploit tools to a clean, isolated machine. Of course, Excel has been known as vector for macro viruses for quite some time and some of the techniques--such as hex-encoding binary data and re-encoding it on a target machine--are known binary insertion vectors but I have not found any prior work on an insider using these techniques to deliver payloads to closed systems. You'll leave my presentation knowing why Excel, umm, excels as an insider attack tool, how to leverage Excel features to load and extract arbitrary binary data from a closed network, and what to do if this really frightens you.


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