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Secure Attention Sequence
A secure attention key (SAK) or secure attention sequence (SAS) is a special key or key combination to be pressed on a computer keyboard before a logging (computer security), login screen which must, to the user, be completely trustworthy. The operating system kernel (computer science), kernel, which interacts directly with the hardware, is able to detect whether the secure attention key has been pressed. When this event is detected, the kernel starts the trusted login processing. The secure attention key is designed to make login spoofing impossible, as the kernel will suspend any program, including those masquerading as the computer's login process, before starting a trustable login operation. Examples Some examples are: * Control-Alt-Delete#Windows NT family, for Windows NT. * Magic SysRq key, default sequence for Linux. Not a true Trusted Computer System Evaluation Criteria, C2-compliant SAK. See also * Control-Alt-Del * Magic SysRq key * Break key References Comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key Combination
computing, a keyboard shortcut also known as hotkey is a series of one or several keys to quickly invoke a software program or perform a preprogrammed action. This action may be part of the standard functionality of the operating system or application program, or it may have been written by the user in a scripting language. Some integrated keyboards also include pointing devices; the definition of exactly what counts as a "key" sometimes differs. The meaning of term "keyboard shortcut" can vary depending on software manufacturer. In Windows, hotkeys consists of a specific key combination used to trigger an action (these are usually system-wide shortcuts that are available in all contexts so long as receiving program is active); mnemonics represent a designated letter in a menu command or toolbar button that when pressed together with the Alt key, activates such command. The term is generally associated with computer keyboards, but many electronic musical instruments now c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Keyboard
A computer keyboard is a peripheral input device modeled after the typewriter keyboard which uses an arrangement of buttons or keys to act as mechanical levers or electronic switches. Replacing early punched cards and paper tape technology, interaction via teleprinter-style keyboards have been the main input method for computers since the 1970s, supplemented by the computer mouse since the 1980s. Keyboard keys (buttons) typically have a set of characters engraved or printed on them, and each press of a key typically corresponds to a single written symbol. However, producing some symbols may require pressing and holding several keys simultaneously or in sequence. While most keys produce characters (letters, numbers or symbols), other keys (such as the escape key) can prompt the computer to execute system commands. In a modern computer, the interpretation of key presses is generally left to the software: the information sent to the computer, the scan code, tells it only whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logging (computer Security)
In computer security, logging in (or logging on, signing in, or signing on) is the process by which an individual gains access to a computer system by identifying and authenticating themselves. The user credentials are typically some form of username and a matching password, and these credentials themselves are sometimes referred to as ''a'' login (or logon, sign-in, sign-on).Oxford Dictionaries definition of ''login''. detail and definition of ''login'' and ''logging in''. In practice, modern secure systems often require a second factor such as |
Operating System
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer from cellular phones and video game consoles to web servers and supercomputers. The dominant general-purpose personal computer operating system is Microsoft Windows with a market share of around 74.99%. macOS by Apple Inc. is in second place (14.84%), and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel (computer Science)
The kernel is a computer program at the core of a computer's operating system and generally has complete control over everything in the system. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources (e.g. I/O, memory, cryptography) via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the utilization of common resources e.g. CPU & cache usage, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup (after the bootloader). It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit. The critical code of the kernel is usually loaded into a separate area of memory, which is protected from access by applicati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Login Spoofing
Login spoofings are techniques used to steal a user's password. The user is presented with an ordinary looking login prompt for username and password, which is actually a malicious program (usually called a Trojan horse) under the control of the attacker. When the username and password are entered, this information is logged or in some way passed along to the attacker, breaching security. To prevent this, some operating systems require a special key combination (called a secure attention key) to be entered before a login screen is presented, for example Control-Alt-Delete. Users should be instructed to report login prompts that appear without having pressed this secure attention sequence. Only the kernel, which is the part of the operating system that interacts directly with the hardware, can detect whether the secure attention key has been pressed, so it cannot be intercepted by third party programs (unless the kernel itself has been compromised). Similarity to phishing While sim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control-Alt-Delete
Control-Alt-Delete (often abbreviated to Ctrl+Alt+Del, also known as the "three-finger salute" or "Security Keys") is a computer keyboard command on IBM PC compatible computers, invoked by pressing the Delete key while holding the Control key, Control and Alt key, Alt keys: . The function of the key combination differs depending on the context but it generally interrupts or facilitates interrupting a function. For instance, in pre-boot environment (before an operating system starts) or in DOS, Windows 3.0 and earlier versions of Windows or OS/2, the key combination Reboot (computing), reboots the computer. Starting with Windows 95, the key combination invokes a task manager or security related component that facilitates ending a Windows session or killing a Hang (computing), frozen application. History The Reboot (computing), soft reboot function via keyboard was originally designed by David Bradley (engineer), David Bradley. Bradley, as the chief engineer of the IBM Personal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magic SysRq Key
The magic SysRq key is a key combination understood by the Linux kernel, which allows the user to perform various low-level commands regardless of the system's state. It is often used to recover from freezes, or to reboot a computer without corrupting the filesystem. Its effect is similar to the computer's hardware reset button (or power switch) but with many more options and much more control. This key combination provides access to powerful features for software development and disaster recovery. In this sense, it can be considered a form of escape sequence. Principal among the offered commands are means to forcibly unmount file systems, kill processes, recover keyboard state, and write unwritten data to disk. With respect to these tasks, this feature serves as a tool of last resort. The magic SysRq key cannot work under certain conditions, such as a kernel panic or a hardware failure preventing the kernel from running properly. Commands The key combination consists o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which includes the kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name "GNU/Linux" to emphasize the importance of GNU software, causing some controversy. Popular Linux distributions include Debian, Fedora Linux, and Ubuntu, the latter of which itself consists of many different distributions and modifications, including Lubuntu and Xubuntu. Commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise. Desktop Linux distributions include a windowing system such as X11 or Wayland, and a desktop environment such as GNOME or KDE Plasma. Distributions intended for ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU operating system, which was written to be a free (libre) replacement for Unix. Linux is provided under the GNU General Public License version 2 only, but it contains files under other compatible licenses. Since the late 1990s, it has been included as part of a large number of operating system distributions, many of which are commonly also called Linux. Linux is deployed on a wide variety of computing systems, such as embedded devices, mobile devices (including its use in the Android operating system), personal computers, servers, mainframes, and supercomputers. It can be tailored for specific architectures and for several usage scenarios using a family of simple commands (that is, without the need of manually editing its source code ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trusted Computer System Evaluation Criteria
Trusted Computer System Evaluation Criteria (TCSEC) is a United States Government Department of Defense (DoD) standard that sets basic requirements for assessing the effectiveness of computer security controls built into a computer system. The TCSEC was used to evaluate, classify, and select computer systems being considered for the processing, storage, and retrieval of sensitive or classified information. The TCSEC, frequently referred to as the Orange Book, is the centerpiece of the DoD ''Rainbow Series'' publications. Initially issued in 1983 by the National Computer Security Center (NCSC), an arm of the National Security Agency, and then updated in 1985, TCSEC was eventually replaced by the Common Criteria international standard, originally published in 2005. Fundamental objectives and requirements On 24 October 2002, The Orange Book (aka DoDD 5200.28-STD) was canceled by DoDD 8500.1, which was later reissued as DoDI 8500.02, on 14 March 2014. Policy The security policy m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel
Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learning * Kernelization, a technique for designing efficient algorithms ** Kernel, a routine that is executed in a vectorized loop, for example in general-purpose computing on graphics processing units *KERNAL, the Commodore operating system Mathematics Objects * Kernel (algebra), a general concept that includes: ** Kernel (linear algebra) or null space, a set of vectors mapped to the zero vector ** Kernel (category theory), a generalization of the kernel of a homomorphism ** Kernel (set theory), an equivalence relation: partition by image under a function ** Difference kernel, a binary equalizer: the kernel of the difference of two functions Functions * Kernel (geometry), the set of points within a polygon from which the whole polygon bound ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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