COMPUTER VIRUSES
A computer virus is a type of malicious software program ("malware") that, when executed, replicates by reproducing itself (copying its own source code) or infecting other computer programs by modifying them.Infecting computer programs can include as well, data files, or the "boot" sector of the hard drive. When this replication succeeds, the affected areas are then said to be "infected" with a computer virus. The term "virus" is also commonly, but erroneously, used to refer to other types of malware. "Malware" encompasses computer viruses along with many other forms of malicious software, such as computer "worms", ransomware, trojan horses, keyloggers, rootkits, spyware, adware, malicious Browser Helper Object (BHOs) and other malicious software. The majority of active malware threats are actually trojan horse programs or computer worms rather than computer viruses. The term computer virus, coined by Fred Cohen in 1985, is a misnomer. Viruses often perform some type of harmful activity on infected host computers, such as acquisition of hard disk space or central processing unit (CPU) time, accessing private information (e.g., credit card numbers), corrupting data, displaying political or humorous messages on the user's screen, spamming their e-mail contacts, logging their keystrokes, or even rendering the computer useless. However, not all viruses carry a destructive "payload" or attempt to hide themselves—the defining characteristic of viruses is that they are self-replicating computer programs which install themselves without user consent.
Virus writers use social engineering deceptions and exploit detailed knowledge of security vulnerabilities to gain access to their hosts' computers and computing resources. The vast majority of viruses target systems running Microsoft Windows, employing a variety of mechanisms to infect new hosts, and often using complex anti-detection/stealth strategies to evade antivirus software.Motives for creating viruses can include seeking profit (e.g., with ransomware), desire to send a political message, personal amusement, to demonstrate that a vulnerability exists in software, for sabotage and denial of service, or simply because they wish to explore cybersecurityissues, artificial life and evolutionary algorithms.
Computer viruses currently cause billions of dollars' worth of economic damage each year, due to causing system failure, wasting computer resources, corrupting data, increasing maintenance costs, etc. In response, free, open-source antivirus tools have been developed, and an industry of antivirus software has cropped up, selling or freely distributing virus protection to users of various operating systems. As of 2005, even though no currently existing antivirus software was able to uncover all computer viruses (especially new ones), computer security researchers are actively searching for new ways to enable antivirus solutions to more effectively detect emerging viruses, before they have already become widely distributed.
Image result for computer virus
Operations and functions
Parts
A viable computer virus must contain a search routine, which locates new files or new disks which are worthwhile targets for infection. Secondly, every computer virus must contain a routine to copy itself into the program which the search routine locates. The three main virus parts are:
Infection mechanism
Infection mechanism (also called 'infection vector'), is how the virus spreads or propagates. A virus typically has a search routine, which locates new files or new disks for infection.
Trigger
The trigger, which is also known as logic bomb, is the compiled version that could be activated any time an executable file with the virus is run that determines the event or condition for the malicious "payload" to be activated or delivered such as a particular date, a particular time, particular presence of another program, capacity of the disk exceeding some limit, or a double-click that opens a particular file.
Payload
The "payload" is the actual body or data that perform the actual malicious purpose of the virus. Payload activity might be noticeable (e.g., because it causes the system to slow down or "freeze"), as most of the time the "payload" itself is the harmful activity, or some times non-destructive but distributive, which is called Virus hoax.
Phases
Virus phases is the life cycle of the computer virus, described by using an analogy to biology. This life cycle can be divided into four phases:
Dormant phase
The virus program is idle during this stage. The virus program has managed to access the target user's computer or software, but during this stage, the virus does not take any action. The virus will eventually be activated by the "trigger" which states which event will execute the virus, such as a date, the presence of another program or file, the capacity of the disk exceeding some limit or the user taking a certain action (e.g., double-clicking on a certain icon, opening an e-mail, etc.). Not all viruses have this stage.
Propagation phase
The virus starts propagating, that is multiplying and self-replicating itself. The virus places a copy of itself into other programs or into certain system areas on the disk. The copy may not be identical to the propagating version; viruses often "morph" or change to evade detection by IT professionals and anti-virus software. Each infected program will now contain a clone of the virus, which will itself enter a propagation phase.Triggering phase
A dormant virus moves into this phase when it is activated, and will now perform the function for which it was intended. The triggering phase can be caused by a variety of system events, including a count of the number of times that this copy of the virus has made copies of itself.
Execution phase
This is the actual work of the virus, where the "payload" will be released. It can be destructive such as deleting files on disk, crashing the system, or corrupting files or relatively harmless such as popping up humorous or political messages on screen.
Infection targets and replication techniques
Computer viruses infect a variety of different subsystems on their host computers and software. One manner of classifying viruses is to analyze whether they reside in binary executables (such as .EXE or .COM files), data files (such as Microsoft Word documents or PDF files), or in the boot sector of the host's hard drive (or some combination of all of these).
Virus writers use social engineering deceptions and exploit detailed knowledge of security vulnerabilities to gain access to their hosts' computers and computing resources. The vast majority of viruses target systems running Microsoft Windows, employing a variety of mechanisms to infect new hosts, and often using complex anti-detection/stealth strategies to evade antivirus software.Motives for creating viruses can include seeking profit (e.g., with ransomware), desire to send a political message, personal amusement, to demonstrate that a vulnerability exists in software, for sabotage and denial of service, or simply because they wish to explore cybersecurityissues, artificial life and evolutionary algorithms.
Computer viruses currently cause billions of dollars' worth of economic damage each year, due to causing system failure, wasting computer resources, corrupting data, increasing maintenance costs, etc. In response, free, open-source antivirus tools have been developed, and an industry of antivirus software has cropped up, selling or freely distributing virus protection to users of various operating systems. As of 2005, even though no currently existing antivirus software was able to uncover all computer viruses (especially new ones), computer security researchers are actively searching for new ways to enable antivirus solutions to more effectively detect emerging viruses, before they have already become widely distributed.
Image result for computer virus
Operations and functions
Parts
A viable computer virus must contain a search routine, which locates new files or new disks which are worthwhile targets for infection. Secondly, every computer virus must contain a routine to copy itself into the program which the search routine locates. The three main virus parts are:
Infection mechanism
Infection mechanism (also called 'infection vector'), is how the virus spreads or propagates. A virus typically has a search routine, which locates new files or new disks for infection.
Trigger
The trigger, which is also known as logic bomb, is the compiled version that could be activated any time an executable file with the virus is run that determines the event or condition for the malicious "payload" to be activated or delivered such as a particular date, a particular time, particular presence of another program, capacity of the disk exceeding some limit, or a double-click that opens a particular file.
Payload
The "payload" is the actual body or data that perform the actual malicious purpose of the virus. Payload activity might be noticeable (e.g., because it causes the system to slow down or "freeze"), as most of the time the "payload" itself is the harmful activity, or some times non-destructive but distributive, which is called Virus hoax.
Phases
Virus phases is the life cycle of the computer virus, described by using an analogy to biology. This life cycle can be divided into four phases:
Dormant phase
The virus program is idle during this stage. The virus program has managed to access the target user's computer or software, but during this stage, the virus does not take any action. The virus will eventually be activated by the "trigger" which states which event will execute the virus, such as a date, the presence of another program or file, the capacity of the disk exceeding some limit or the user taking a certain action (e.g., double-clicking on a certain icon, opening an e-mail, etc.). Not all viruses have this stage.
Propagation phase
The virus starts propagating, that is multiplying and self-replicating itself. The virus places a copy of itself into other programs or into certain system areas on the disk. The copy may not be identical to the propagating version; viruses often "morph" or change to evade detection by IT professionals and anti-virus software. Each infected program will now contain a clone of the virus, which will itself enter a propagation phase.Triggering phase
A dormant virus moves into this phase when it is activated, and will now perform the function for which it was intended. The triggering phase can be caused by a variety of system events, including a count of the number of times that this copy of the virus has made copies of itself.
Execution phase
This is the actual work of the virus, where the "payload" will be released. It can be destructive such as deleting files on disk, crashing the system, or corrupting files or relatively harmless such as popping up humorous or political messages on screen.
Infection targets and replication techniques
Computer viruses infect a variety of different subsystems on their host computers and software. One manner of classifying viruses is to analyze whether they reside in binary executables (such as .EXE or .COM files), data files (such as Microsoft Word documents or PDF files), or in the boot sector of the host's hard drive (or some combination of all of these).
0 comments: