Useless Crap? No, not nearly! Advance your binary exploitation skills by solving a sophisticated CTF challenge

PWN challenges are my favorite tasks at CTF contests. Such tasks effectively train you in real-life code analysis, while their write-ups usually describe all fine details, even those already addressed by other authors. Today, I will explain how to solve a task named “Useless Crap” by its author (it’s available on TG:HACK 2020). The author estimates its difficulty as hard. The task is very challenging indeed, and it took me almost twelve hours to complete it at the contest.
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Spying penguin. Windows post-exploitation with a Linux-based VM

Windows-based systems are significantly more resistant against MITM attacks in comparison with Linux-based ones. The reason is simple: Windows does not include a handy mechanism to forward transit packets. Today, I will explain how to use a minimalist Linux system running on a virtual machine as a gateway. The attack also involves bridged network interfaces that grant the guest OS full L2 access to the network segment where the compromised Windows system is located. The VM will be deployed using VirtualBox.
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MicroB. Writing BASIC in assembler language and squeezing it into 512 bytes

Want some practice in assembler? Today, I will show step-by-step how to write a BASIC interpreter and run it from the boot sector of your PC. My interpreter includes overlapping subprograms with branching recursion – otherwise, BASIC won’t fit in 512 bytes. It’s quite possible that this project becomes the most sophisticated program in your life. But after writing it by your own hands, you will be able to rightfully call yourself a hacker.
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