This technique can be used by a virus or worm to gain momentum and spread before being noticed. To be considered a logic bomb, the payload should be unwanted and unknown to the user of the software. As an example, trial programs with code that disables certain functionality after a set time are not normally regarded as logic bombs. Sorry, I have to agree with polymorphic virus.
Furthermore, a system attack often exploits an unintentional security flaw to perform intentional damage. From reading the popular press see Sidebar , you might conclude that intentional security incidents called cyber attacks are the biggest security threat today.
In fact, plain, unintentional, human errors cause much more damage. Regrettably, we do not have techniques to eliminate or address all program security flaws. There are two reasons for this distressing situation. Program controls apply at the level of the individual program and programmer. When we test a system, we try to make sure that the functionality prescribed in the requirements is implemented in the code. That is, we take a "should do" checklist and verify that the code does what it is supposed to do.
However, security is also about preventing certain actions: a "shouldn't do" list. It is almost impossible to ensure that a program does precisely what its designer or user intended, and nothing more. Regardless of designer or programmer intent, in a large and complex system, the number of pieces that have to fit together properly interact in an unmanageably large number of ways.
We are forced to examine and test the code for typical or likely cases; we cannot exhaustively test every state and data combination to verify a system's behavior. So sheer size and complexity preclude total flaw prevention or mediation.
Programmers intending to implant malicious code can take advantage of this incompleteness and hide some flaws successfully, despite our best efforts. Part of CERT's mission is to warn users and developers of new problems and also to provide information on ways to fix them. According to the CERT coordination center, fewer than known vulnerabilities were reported in , and that number ranged between and from to But the number increased dramatically in , with over 1, known vulnerabilities in , almost 2, in , and an expectation of at least 3, in over 1, in the first quarter of How does that translate into cyber attacks?
The CERT reported 3, security incidents in , 9, in , 21, in , and 52, in But in the first quarter of there were already 26, incidents, so it seems as if the exponential growth rate will continue [HOU02]. Moreover, as of June , Symantec's Norton antivirus software checked for 61, known virus patterns, and McAfee's product could detect over 50, [BER01]. The Computer Security Institute and the FBI cooperate to take an annual survey of approximately large institutions: companies, government organizations, and educational institutions [CSI02].
Of the respondents, 90 percent detected security breaches, 25 percent identified between two and five events, and 37 percent reported more than ten. A survey of network security personnel revealed that more than 75 percent of government respondents experienced attacks to their networks; more than half said the attacks were frequent. However, 60 percent of respondents admitted that they could do more to make their systems more secure; the respondents claimed that they simply lacked time and staff to address the security issues [BUS01].
Programming and software engineering techniques change and evolve far more rapidly than do computer security techniques. Still, the situation is far from bleak. Computer security has much to offer to program security. By understanding what can go wrong and how to protect against it, we can devise techniques and tools to secure most computer applications. To aid our understanding of the problems and their prevention or correction, we can define categories that distinguish one kind of problem from another.
For example, Landwehr et al. They further divide intentional flaws into malicious and nonmalicious ones. In the taxonomy, the inadvertent flaws fall into six categories:. This list gives us a useful overview of the ways programs can fail to meet their security requirements. We leave our discussion of the pitfalls of identification and authentication for Chapter 4, in which we also investigate separation into execution domains.
In this chapter, we address the other categories, each of which has interesting examples. I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time. Pearson Education, Inc. This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.
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Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey. Antivirus acts against harmful virus-infected adverts and websites by denying them direct access to your computer network. Virus protection and transmission prevention: It identifies any possible infection and then attempts to eliminate it.
Hackers and data thieves are thwarted: Antivirus do regular checks to see if there are any hackers or hacking-related apps on the network. As a result, antivirus offers complete security against hackers. Protected against devices that can be detached: Antivirus scans all removable devices for potential viruses, ensuring that no viruses are transferred. To improve security from web, restrict website access: Antivirus restricts your online access in order to prevent you from accessing unauthorized networks.
This is done to ensure that you only visit websites that are safe and non-harmful to your computer. Password Protection: Using antivirus, you should consider using a password manager for added security. Popping up of Advertisements: Apart from commercial antivirus applications, free antivirus must make money in some way. One approach to attaining these is through advertising.
Many times these advertisements degrade the user experience by popping up every time. Security Holes: When security flaws exist in the operating system or networking software, the virus will be able to defeat antivirus protection. The antivirus software will be ineffective unless the user takes steps to keep it updated.
No customer care service: There will be no customer service provided unless you pay for the premium version. If an issue arises, the only method to solve it is to use forums and knowledge resources. Sample Questions Question 1. What is a computer virus? Robert Thomas, an engineer at BBN Technologies developed the first known computer virus in the year The message displayed on infected Apple Computers was a humorous one. The virus was developed by Richard Skrenta, a teenager in the year A computer virus is one type of malware that inserts its virus code to multiply itself by altering the programs and applications.
The computer gets infected through the replication of malicious code. Computer viruses come in different forms to infect the system in different ways. Find some of the most common type of computer viruses here,. Boot Sector Virus — This type of virus infects the master boot record and it is challenging and a complex task to remove this virus and often requires the system to be formatted.
Mostly it spreads through removable media. Direct Action Virus — This is also called non-resident virus, it gets installed or stays hidden in the computer memory. It stays attached to the specific type of files that it infect. Resident Virus — Unlike direct action viruses, resident viruses get installed on the computer. It is difficult to identify the virus and it is even difficult to remove a resident virus. Multipartite Virus — This type of virus spreads through multiple ways.
It infects both the boot sector and executable files at the same time. Polymorphic Virus — These type of viruses are difficult to identify with a traditional anti-virus program.
This is because the polymorphic viruses alters its signature pattern whenever it replicates. Overwrite Virus — This type of virus deletes all the files that it infects. The only possible mechanism to remove is to delete the infected files and the end-user has to lose all the contents in it. Identifying the overwrite virus is difficult as it spreads through emails.
This is called so as they fill up the empty spaces between the code and hence does not cause any damage to the file. File infectors: Few file infector viruses come attached with program files, such as. Some file infector viruses infect any program for which execution is requested, including. Consequently, when the particular program is loaded, the virus is also loaded. Besides these, the other file infector viruses come as a completely included program or script sent in email attachments.
Macro viruses: As the name suggests, the macro viruses particularly target macro language commands in applications like Microsoft Word. The same is implied on other programs too. In MS Word, the macros are keystrokes that are embedded in the documents or saved sequences for commands. The macro viruses are designed to add their malicious code to the genuine macro sequences in a Word file.
However, as the years went by, Microsoft Word witnessed disabling of macros by default in more recent versions. Thus, the cybercriminals started to use social engineering schemes to target users. In the process, they trick the user and enable macros to launch the virus. Since macro viruses are making a come back in the recent years, Microsoft quickly retaliated by adding a new feature in Office The feature enables security managers to selectively enable macro use.
As a matter of fact, it can be enabled for trusted workflows and blocked if required across the organization. As the name says it all, the virus after attacking the computer starts overwriting files with its own code. Not to be taken lightly, these viruses are more capable of targeting specific files or applications or systematically overwrite all files on an infected device.
On the flipside, the overwrite virus is capable of installing a new code in the files or applications which programs them to spread the virus to additional files, applications, and systems. Polymorphic Viruses: More and more cybercriminals are depending on the polymorphic virus. It is a malware type which has the ability to change or mutate its underlying code without changing its basic functions or features.
This helps the virus on a computer or network to evade detection from many antimalware and threat detection products. Since virus removal programs depend on identifying signatures of malware, these viruses are carefully designed to escape detection and identification. When a security software detects a polymorphic virus, the virus modifies itself thereby, it is no longer detectable using the previous signature.
Resident Viruses: The Resident virus implants itself in the memory of a computer. Basically, the original virus program is not required to infect new files or applications. Even when the original virus is deleted, the version stored in memory can be activated. This happens when the computer OS loads certain applications or functions.
Rootkit Viruses: The rootkit virus is a malware type which secretly installs an illegal rootkit on an infected system. This opens the door for attackers and gives them full control of the system. The attacker will be able to fundamentally modify or disable functions and programs. Like other sophisticated viruses, the rootkit virus is also created to bypass antivirus software. The latest versions of major antivirus and antimalware programs include rootkit scanning.
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