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System Service Dispatch Table
The System Service Descriptor Table (SSDT) is an internal dispatch table within Microsoft Windows. Function The SSDT maps syscalls to kernel function addresses. When a syscall is issued by a user space application, it contains the service index as parameter to indicate which syscall is called. The SSDT is then used to resolve the address of the corresponding function within ntoskrnl.exe. In modern Windows kernels, two SSDTs are used: One for generic routines (''KeServiceDescriptorTable'') and a second (''KeServiceDescriptorTableShadow'') for graphical routines. A parameter passed by the calling userspace application determines which SSDT shall be used. Hooking Modification of the SSDT allows to redirect syscalls to routines outside the kernel. These routines can be either used to hide the presence of software or to act as a backdoor to allow attackers permanent code execution with kernel privileges. For both reasons, hooking SSDT calls is often used as a technique in both W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Dispatch Table
In computer science, a dispatch table is a table of pointers or memory addresses to functions or methods. Use of such a table is a common technique when implementing late binding in object-oriented programming. Perl implementation The following shows one way to implement a dispatch table in Perl, using a hash to store references to code (also known as function pointers). # Define the table using one anonymous code-ref and one named code-ref my %dispatch = ( "-h" => sub , "-g" => \&say_goodbye ); sub say_goodbye # Fetch the code ref from the table, and invoke it my $sub = $dispatch; print $sub ? $sub->() : "unknown argument\n"; Running this Perl program as perl greet -h will produce "hello", and running it as perl greet -g will produce "goodbye". JavaScript implementation Following is a demo of implementing dispatch table in JavaScript: var thingsWeCanDo = ; var doSomething = function(doWhat) Virtual method tables In object-oriented programming languag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Microsoft Windows
Windows is a group of several Proprietary software, proprietary graphical user interface, graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for servers, and Windows IoT for embedded systems. Defunct Windows families include Windows 9x, Windows Mobile, and Windows Phone. The first version of Windows was released on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Windows is the most popular desktop operating system in the world, with Usage share of operating systems, 75% market share , according to StatCounter. However, Windows is not the most used operating system when including both mobile and desktop OSes, due to Android (operating system), Android's massive growth. , the most recent version of Windows is Windows 11 for consumer Personal compu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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User Space
A modern computer operating system usually segregates virtual memory into user space and kernel space. Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour. Kernel space is strictly reserved for running a privileged operating system kernel, kernel extensions, and most device drivers. In contrast, user space is the memory area where application software and some drivers execute. Overview The term user space (or userland) refers to all code that runs outside the operating system's kernel. User space usually refers to the various programs and libraries that the operating system uses to interact with the kernel: software that performs input/output, manipulates file system objects, application software, etc. Each user space process normally runs in its own virtual memory space, and, unless explicitly allowed, cannot access the memory of other processes. This is the basis for memory protection in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Hooking
In computer programming, the term hooking covers a range of techniques used to alter or augment the behaviour of an operating system, of applications, or of other software components by intercepting function calls or messages or events passed between software components. Code that handles such intercepted function calls, events or messages is called a hook. Hooking is used for many purposes, including debugging and extending functionality. Examples might include intercepting keyboard or mouse event messages before they reach an application, or intercepting operating system calls in order to monitor behavior or modify the function of an application or other component. It is also widely used in benchmarking programs, for example frame rate measuring in 3D games, where the output and input is done through hooking. Hooking can also be used by malicious code. For example, rootkits, pieces of software that try to make themselves invisible by faking the output of API calls that wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Rootkit
A rootkit is a collection of computer software, typically malicious, designed to enable access to a computer or an area of its software that is not otherwise allowed (for example, to an unauthorized user) and often masks its existence or the existence of other software. The term ''rootkit'' is a compound of "root" (the traditional name of the privileged account on Unix-like operating systems) and the word "kit" (which refers to the software components that implement the tool). The term "rootkit" has negative connotations through its association with malware. Rootkit installation can be automated, or an attacker can install it after having obtained root or administrator access. Obtaining this access is a result of direct attack on a system, i.e. exploiting a vulnerability (such as privilege escalation) or a password (obtained by cracking or social engineering tactics like "phishing"). Once installed, it becomes possible to hide the intrusion as well as to maintain privileged ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Antivirus Software
Antivirus software (abbreviated to AV software), also known as anti-malware, is a computer program used to prevent, detect, and remove malware. Antivirus software was originally developed to detect and remove computer viruses, hence the name. However, with the proliferation of other malware, antivirus software started to protect from other computer threats. In particular, modern antivirus software can protect users from malicious browser helper objects (BHOs), browser hijackers, ransomware, keyloggers, backdoors, rootkits, trojan horses, worms, malicious LSPs, dialers, fraud tools, adware, and spyware. Some products also include protection from other computer threats, such as infected and malicious URLs, spam, scam and phishing attacks, online identity (privacy), online banking attacks, social engineering techniques, advanced persistent threat (APT), and botnet DDoS attacks. History 1949–1980 period (pre-antivirus days) Although the roots of the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Exploit (computer Security)
An exploit (from the English verb ''to exploit'', meaning "to use something to one’s own advantage") is a piece of software, a chunk of data, or a sequence of commands that takes advantage of a bug or vulnerability to cause unintended or unanticipated behavior to occur on computer software, hardware, or something electronic (usually computerized). Such behavior frequently includes things like gaining control of a computer system, allowing privilege escalation, or a denial-of-service (DoS or related DDoS) attack. In lay terms, some exploit is akin to a 'hack'. Classification There are several methods of classifying exploits. The most common is by how the exploit communicates to the vulnerable software. A ''remote exploit'' works over a network and exploits the security vulnerability without any prior access to the vulnerable system. A ''local exploit'' requires prior access to the vulnerable system and usually increases the privileges of the person running the exploit past t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Race Condition
A race condition or race hazard is the condition of an electronics, software, or other system where the system's substantive behavior is dependent on the sequence or timing of other uncontrollable events. It becomes a bug when one or more of the possible behaviors is undesirable. The term ''race condition'' was already in use by 1954, for example in David A. Huffman's doctoral thesis "The synthesis of sequential switching circuits". Race conditions can occur especially in logic circuits, multithreaded, or distributed software programs. In electronics A typical example of a race condition may occur when a logic gate combines signals that have traveled along different paths from the same source. The inputs to the gate can change at slightly different times in response to a change in the source signal. The output may, for a brief period, change to an unwanted state before settling back to the designed state. Certain systems can tolerate such glitches but if this output functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Windows API
The Windows API, informally WinAPI, is Microsoft's core set of application programming interfaces (APIs) available in the Microsoft Windows operating systems. The name Windows API collectively refers to several different platform implementations that are often referred to by their own names (for example, Win32 API); see the versions section. Almost all Windows programs interact with the Windows API. On the Windows NT line of operating systems, a small number (such as programs started early in the Windows startup process) use the Native API. Developer support is available in the form of a software development kit, Microsoft Windows SDK, providing documentation and tools needed to build software based on the Windows API and associated Windows interfaces. The Windows API (Win32) is focused mainly on the programming language C in that its exposed functions and data structures are described in that language in recent versions of its documentation. However, the API may be used by an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Native API
The Native API is a lightweight application programming interface (API) used by Windows NT and user mode applications. This API is used in the early stages of Windows NT startup process, when other components and APIs are still unavailable. Therefore, a few Windows components, such as the Client/Server Runtime Subsystem (CSRSS), are implemented using the Native API. The Native API is also used by Subroutine, subroutines such as those in kernel32.dll that implement the Windows API, the API based on which most of the Windows components are created. Most of the Native API calls are implemented in ntoskrnl.exe and are exposed to user mode by ntdll.dll. The entry point of ntdll.dll is LdrInitializeThunk. Native API calls are handled by the Windows NT kernel, kernel via the System Service Descriptor Table (SSDT). Function groups The Native API comprises many functions. They include C standard library, C runtime functions that are needed for a very basic C (programming language), C ru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Rootkit
A rootkit is a collection of computer software, typically malicious, designed to enable access to a computer or an area of its software that is not otherwise allowed (for example, to an unauthorized user) and often masks its existence or the existence of other software. The term ''rootkit'' is a compound of "root" (the traditional name of the privileged account on Unix-like operating systems) and the word "kit" (which refers to the software components that implement the tool). The term "rootkit" has negative connotations through its association with malware. Rootkit installation can be automated, or an attacker can install it after having obtained root or administrator access. Obtaining this access is a result of direct attack on a system, i.e. exploiting a vulnerability (such as privilege escalation) or a password (obtained by cracking or social engineering tactics like "phishing"). Once installed, it becomes possible to hide the intrusion as well as to maintain privileged ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Windows Technology
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for servers, and Windows IoT for embedded systems. Defunct Windows families include Windows 9x, Windows Mobile, and Windows Phone. The first version of Windows was released on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Windows is the most popular desktop operating system in the world, with 75% market share , according to StatCounter. However, Windows is not the most used operating system when including both mobile and desktop OSes, due to Android's massive growth. , the most recent version of Windows is Windows 11 for consumer PCs and tablets, Windows 11 Enterprise for corporations, and Windows Server 2022 for servers. Genealogy By ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |