This class provides a distilled understanding of some OS mechanisms such as memory management, segmentation, paging, interrupts, and port IO. This knowledge is directly relevant for the future Rootkits and Advanced x86: Virtualization with Intel VT-x classes.
Building upon the Introductory Intel x86 class, this class goes into more depth on topics already learned, and introduces more advanced topics that dive deeper into how Intel-based systems work.
Topics include, but are not limited to:
•Physical and virtual memory and how a limited amount of physical memory is represented as much more virtual memory through a multilevel paging system. We will also talk about memory segmentation.
•The hardware basis for kernel versus userspace separation and how software transitions between the two. This portion answers the question of why does x86 have 4 “rings”, with ring 0 being the most privileged, and ring 3 being the least.
•Hardware and software interrupts, and how they are the basis for debugging.
•Input/Output instructions and how these allow the CPU to talk to peripherals.
Example applications include showing how hardware and memory mechanisms are used for software exploits, anti-debug techniques, rootkit hiding, and direct hardware access for keystroke logging.
This material includes labs on:
•Using WinDbg to perform kernel debugging on a virtual machine (which is equally applicable for debugging a real machine.)
•Using a custom WinDbg plugin to examine the Local (memory segment) Descriptor Table (LDT), and Global (memory segment) Descriptor Table (GDT) in order to understand how Windows sets memory segment ranges and permissions for userspace and kernel space.
•Using WinDbg and the !pte command to understand how Windows organizes its paging structures which map physical memory to virtual memory.
•Investigating where exactly the XD/NX bit is set in order to make memory as non-executable (which Microsoft calls Data Execution Prevention (DEP)), to prevent some types of exploits from succeeding.
•Using the Read Timestamp Counter (RDTSC) instruction to profile code execution time. Also, using a profile of code execution time to change a program’s behavior in the presence of a debugger (e.g. executing different code if the code appears to have been stopped at a breakpoint.)
•Printing information about task state segments, which hold information that is used to find the kernel stack when an interrupt occurs.
•Watching what does and doesn’t change when a software interrupt is used to transfer control from userspace to kernel.
•Reading the Interrupt Descriptor Table (IDT) and understanding the security implications of changes to it.
•Understanding how RedPill uses the IDT in order to detect that a system is virtualized.
•Having a process read its own memory when a software breakpoint is set, in order to see how a debugger will change memory to set the breakpoint but hide the change from the user.
•Watch how hardware-based breakpoints manipulate dedicated debug registers.
•Using port input/output to access the backdoor communications channel that VMWare uses in order to send copy/paste, mouse movement, and other events in and out of a VM.
•Using port I/O in order to talk directly to the PS2 keyboard controller in order to sniff keystrokes or flash keyboard LEDs.
Knowledge of this material is strongly encouraged for future classes such as Rootkits and Advanced x86: Virtualization with Intel VT-x.
Experienced Computer Scientists analyze and solve computational problems at a level of abstraction that is beyond that of any particular programming language. This two-part class is designed to train students in the mathematical concepts and process of "Algorithmic Thinking", allowing them to build simpler, more efficient solutions to computational problems.
A free online course for primary and secondary school teachers who are tackling the Computing curriculum in England. This free online course aims to help teachers in primary and secondary schools, especially those who previously taught other subjects including ICT. It was originally created by UEA with sponsorship from Computing at School (CAS) and BT. CAS have asked the National STEM Learning Centre to host a fourth run of this successful course.
This course introduces the basics of Digital Signal Processing and computational acoustics, motivated by the vibrational physics of real-world objects and systems. We will build from a simple mass-spring and pendulum to demonstrate oscillation, how to simulate those systems in the computer, and also prove that simple oscillation behaves as a sine wave. From that we move to plucked strings and struck bars, showing both solutions as combined traveling waves and combined sine wave harmonics.
This two-part course is designed to help students with very little or no computing background learn the basics of building simple interactive applications. Our language of choice, Python, is an easy-to learn, high-level computer language that is used in many of the computational courses offered on Coursera.
O curso apresenta uma introdução aos processadores multicore de uma forma acessível, sem que haja a necessidade de conhecimentos prévios na área de ciência da computação. A partir desta introdução serão feitas relações com outras áreas da computação, de forma a despertar o interesse do aluno para os diferentes cursos oferecidos pela Faculdade de Informática da PUCRS.
The impact of technology and networks on our lives, culture, and society continues to increase. The very fact that you can take this course from anywhere in the world requires a technological infrastructure that was designed, engineered, and built over the past sixty years. To function in an information-centric world, we need to understand the workings of network technology. This course will open up the Internet and show you how it was created, who created it and how it works. Along the way we will meet many of the innovators who developed the Internet and Web technologies that we use today.
This two-part course is designed to help students with very little or no computing background learn the basics of building simple interactive applications. Our language of choice, Python, is an easy-to learn, high-level computer language that is used in many of the computational courses offered on Coursera. To make learning Python easy, we have developed a new browser-based programming environment that makes developing interactive applications in Python simple. These applications will involve windows whose contents are graphical and respond to buttons, the keyboard and the mouse.
A computer science principles course for anyone who wants to learn how to translate ideas into code. Discover the big ideas and thinking practices in computer science plus learn how to code using one of the friendliest programming languages, Snap! (based on Scratch).
This two-part course builds upon the programming skills that you learned in our Introduction to Interactive Programming in Python course. We will augment those skills with both important programming practices and critical mathematical problem solving skills. These skills underlie larger scale computational problem solving and programming.