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Compression Virus
A compression virus is an example of a benevolent computer virus, invented by Fred Cohen. It searches for an uninfected executable file, compresses the file and prepends itself to it. The virus can be described in pseudo code program compression-virus:= The ''01234567'' is the virus signature, and is used to make sure (''if first-line-of-file = 01234567'') the file is not already infected. The virus then asks for permission (''ask-permission'') to infect a random executable (''get-random-executable-file''). If the permission is granted, it compresses the executable (''infect-executable''), prepends itself to it (''prepend''), uncompresses the current executable file (''uncompress the-rest-of-this-file'') into a temporary file (''tmpfile'') and runs it (''run tmpfile''). ''Cruncher'' is an example of a compression virus, a strain of which – ''Cruncher.2092''{{Cite web , url=http://vil.nai.com/vil/content/v_318.htm , title=McAfee article on Cruncher.2092, ''read Characterist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Virus
A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer programs and inserting its own code. If this replication succeeds, the affected areas are then said to be "infected" with a computer virus, a metaphor derived from biological viruses. Computer viruses generally require a host program. The virus writes its own code into the host program. When the program runs, the written virus program is executed first, causing infection and damage. A computer worm does not need a host program, as it is an independent program or code chunk. Therefore, it is not restricted by the host program, but can run independently and actively carry out attacks. Virus writers use social engineering deceptions and exploit detailed knowledge of security vulnerabilities to initially infect systems and to spread the virus. Viruses use complex anti-detection/stealth strategies to evade antivirus software. Motives for creating viruses can inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fred Cohen
Frederick B. Cohen (born 1956) is an American computer scientist and best known as the inventor of computer virus defense techniques. He gave the definition of "computer virus". Cohen is best known for his pioneering work on computer viruses, the invention of high integrity operating system mechanisms now in widespread use, and automation of protection management functions. In 1983, while a student at the University of Southern California's School of Engineering (currently the Viterbi School of Engineering), he wrote a program for a parasitic application that seized control of computer operations, one of the first computer viruses, in Leonard Adleman’s class. He wrote a short program, as an experiment, that could "infect" computers, make copies of itself, and spread from one machine to another. It was hidden inside a larger, legitimate program, which was loaded into a computer on a floppy disk. One of the few solid theoretical results in the study of computer viruses is Cohe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Executable
In computing, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instruction (computer science), instructions", as opposed to a data (computing), data file that must be interpreted (parser, parsed) by a program to be meaningful. The exact interpretation depends upon the use. "Instructions" is traditionally taken to mean machine code instructions for a physical central processing unit, CPU. In some contexts, a file containing scripting instructions (such as bytecode) may also be considered executable. Generation of executable files Executable files can be hand-coded in machine language, although it is far more convenient to develop software as source code in a high-level language that can be easily understood by humans. In some cases, source code might be specified in assembly language instead, which remains human-readable while being close ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Virus
A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer programs and inserting its own code. If this replication succeeds, the affected areas are then said to be "infected" with a computer virus, a metaphor derived from biological viruses. Computer viruses generally require a host program. The virus writes its own code into the host program. When the program runs, the written virus program is executed first, causing infection and damage. A computer worm does not need a host program, as it is an independent program or code chunk. Therefore, it is not restricted by the host program, but can run independently and actively carry out attacks. Virus writers use social engineering deceptions and exploit detailed knowledge of security vulnerabilities to initially infect systems and to spread the virus. Viruses use complex anti-detection/stealth strategies to evade antivirus software. Motives for creating viruses can inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding; encoding done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a signal. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temporary File
A temporary file is a file created to store information temporarily, either for a program's intermediate use or for transfer to a permanent file when complete. It may be created by computer programs for a variety of purposes, such as when a program cannot allocate enough memory for its tasks, when the program is working on data bigger than the architecture's address space, or as a primitive form of inter-process communication. Auxiliary memory Modern operating systems employ virtual memory, however programs that use large amounts of data (e.g. video editing) may need to create temporary file(s). Inter-process communication Most operating systems offer primitives such as pipes, sockets or shared memory to pass data among programs, but often the simplest way (especially for programs that follow the Unix philosophy) is to write data into a temporary file and inform the receiving program of the location of the temporary file. Creation Operating systems and programming languages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
McAfee
McAfee Corp. ( ), formerly known as McAfee Associates, Inc. from 1987 to 1997 and 2004 to 2014, Network Associates Inc. from 1997 to 2004, and Intel Security Group from 2014 to 2017, is an American global computer security software company headquartered in San Jose, California. The company was purchased by Intel in February 2011, and became part of the Intel Security division. In 2017, Intel had a strategic deal with TPG Capital and converted Intel Security into a joint venture between both companies called McAfee. Thoma Bravo took a minority stake in the new company, and Intel retained a 49% stake. The owners took McAfee public on the NASDAQ in 2020, and in 2022 an investor group led by Advent International Corporation took it private again. History 1987–1999 The company was founded in 1987 as McAfee Associates, named for its founder John McAfee, who resigned from the company in 1994. McAfee was incorporated in the state of Delaware in 1992. In 1993, McAfee stepped do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
COM File
A COM file is a type of simple executable file. On the Digital Equipment Corporation (DEC) VAX operating systems of the 1970s, .COM was used as a filename extension for text files containing commands to be issued to the operating system (similar to a batch file). With the introduction of Digital Research's CP/M (a microcomputer operating system), the type of files commonly associated with COM extension changed to that of executable files. This convention was later carried over to DOS. Even when complemented by the more general .exe, EXE file format for executables, the compact COM files remained viable and frequently used under DOS. The .COM file name extension has no relation to the .com (for "commercial") top-level Internet domain name. However, this similarity in name has been exploited by malware writers. DOS binary format The COM format is the original binary executable format used in CP/M (including SCP (operating system), SCP and MSX-DOS) as well as DOS. It is very sim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
