This number is called a “scan code” (the name highlights the fact that the computer scans the keyboard to search for keystrokes). It uses an 8042 microcontroller which constantly scans keys being pressed on the keyboard independently of central CPU activity.Įach key on the keyboard has a specific number assigned to it this is linked to keyboard matrix map and is not directly dependent on the value shown on the surface of the key itself. Consequently, it could be said that a PC keyboard is itself a small computer system. There are two micro-controllers which support the processing of keyboard input data one is part of the motherboard, the other is within the keyboard itself. Today, the majority of keyboards are a separate device connected to the computer via a port – most frequently PS/2 or USB. The keyboard as a physical device: how it works Chapter 27, “A model of hardware input and the local input condition” contains a description of the high level part of the process by which keyboard input is processed (in user mode). ![]() ![]() Jeffrey Richter’s book ‘Creating effective Win32 applications for 64-bit Windows”.The section related to “HID / Human Input Devices” of the MSDN library, which describes the low-level (driver) part of the process by which keyboard input is processed.The second chapter, “The Keyboard” described how a keyboard functions, the ports used, and keyboard hardware interrupts “Apparatnoe obeshpechenie IBM PC” by Alexander Frolov and Grigory Frolov, Volume 2, Book 1.To describe the process – from a key being pressed on the keyboard to the keyboard system interrupt controller being activated and an active WM_KEYDOWN message appearing, three sources have been used: However, before examining specific types of keylogger, it’s necessary to understand how data entered via the keyboard is processed by Windows. There are several basic technologies which can be used to intercept keystrokes and mouse events, and many keyloggers use these technologies. Processing data entered via the keyboard in Windows Backdoor Trojans typically come with a built-in keylogger and the confidential data is relayed to a remote cybercriminal to be used to make money illegally or gain unauthorized access to a network or other resource. Used by a third-party to obtain confidential data (login details, passwords, credit card numbers, PINs, etc.) by intercepting key presses. Instead, we focus on understanding how keyloggers work, so we can better implement effective protection against them. It should be stressed that this article does not include any keylogger source code we do not share the opinion of some researchers who believe it is acceptable to publish such code. Other users, who are not part of this target group, should simply be aware that Windows offers a multitude of ways in which data entered via the keyboard can be harvested, although the vast majority of keyloggers only use two of these methods (see: Designing keyloggers, the first part of the article). This article is written for technical specialists and experienced users. This article provides both an overview of which links exist in this chain, and how both software and hardware keyloggers work. As was noted in the first article, keyloggers are essentially designed to be injected between any two links in the chain whereby a signal is transmitted from a key being pressed to symbols appearing on the screen. It offers a detailed analysis of the technical aspects and inner workings of keyloggers. This article is a continuation of the previous report on keyloggers. ![]() Keyloggers: How they work and how to detect them (Part 1)
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