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Exercise 4. Read the text and answer the questions following it.




 

Text INTERNET SECURITY

Internet security is a branch of computer security specifically related to the Internet, often involving browser security but also network security on a more general level as it applies to other applications or operating systems on a whole. Its objective is to establish rules and measures to use against attacks over the Internet. The Internet represents an insecure channel for exchanging information leading to a high risk of intrusion or fraud, such as phishing. Different methods have been used to protect the transfer of data, including encryption.

Firewalls

A firewall controls access between networks. It generally consists of gateways and filters which vary from one firewall to another. Firewalls also screen network traffic and are able to block traffic that is dangerous. Firewalls act as the intermediate server between SMTP and HTTP connections.

Role of firewalls in Internet security and web security

Firewalls impose restrictions on incoming and outgoing packets to and from private networks. All the traffic, whether incoming or outgoing, must pass through the firewall; only authorized traffic is allowed to pass through it. Firewalls create checkpoints between an internal private network and the public Internet, also known as choke points. Firewalls can create choke points based on IP source and TCP port number. They can also serve as the platform for IPsec. Using tunnel mode capability, firewall can be used to implement VPNs. Firewalls can also limit network exposure by hiding the internal network system and information from the public Internet.

Malicious software and antivirus

Malware

Commonly, a computer user can be tricked or forced into downloading software onto a computer that is of malicious intent. Such programs are known as malware and come in many forms, such as viruses, Trojan horses, spyware, and worms. Malicious software is sometimes used to form botnets.

Viruses

Viruses are programs that can replicate their structures or effects by infecting other files or structures on a computer. The common use of a virus is to take over a computer to steal data.

Worms

Worms are programs that can replicate themselves throughout a computer network, performing malicious tasks throughout.

Trojan horse

A Trojan horse (commonly known as a Trojan) is a general term for malicious software that pretends to be harmless so that a user willingly allows it to be downloaded onto the computer.

Ransomware and Scareware

Ransomware comprises a class of malware which restricts access to the computer system that it infects, and demands a ransom paid to the creator of the malware in order for the restriction to be removed. Some forms of ransomware encrypt files on the system's hard drive (cryptoviral extortion), while some may simply lock the system and display messages intended to coax the user into paying.

Scareware, nowadays included into the class of malware known as FraudTool, comprises several classes of ransomware or scam software with malicious payloads, usually of limited or no benefit, that are sold to consumers via certain unethical marketing practices. The selling approach uses social engineering to cause shock, anxiety, or the perception of a threat, generally directed at an unsuspecting user. Some forms of spyware and adware also use scareware tactics.

A tactic frequently used by criminals involves convincing users that a virus has infected their computer, then suggesting that they download (and pay for) fake antivirus software to remove it. Usually the virus is entirely fictional and the software is non-functional or malware itself. According to the Anti-Phishing Working Group, the number of scareware packages in circulation rose from 2,850 to 9,287 in the second half of 2008. In the first half of 2009, the APWG identified a 585% increase in scareware programs.

The "scareware" label can also apply to any application or virus (not necessarily sold as above) which pranks users with intent to cause anxiety or panic.

Botnet

A botnet is a network of "zombie" computers that have been taken over by a "bot" that performs large-scale malicious acts for the creator of the botnet.

Spyware

The term spyware refers to programs that surreptitiously monitor activity on a computer system and report that information to others without the user's consent.

Antivirus

Antivirus programs and Internet security programs are useful in protecting a computer or programmable device from malware.

Such programs are used to detect and usually eliminate viruses; however, it is now common to see security suites, containing also firewalls, anti-spyware, theft protection, and so on to more thoroughly protect users.

Traditionally, a user would pay for antivirus software; however, computer users now can, and do, download from a host of free security applications on the Internet.

Denial-of-service attack

A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the concerted efforts of person or persons to prevent an Internetsite or service from functioning efficiently or at all, temporarily or indefinitely.

Browser choice

Web browser statistics tend to affect the amount a Web browser is exploited. For example, Internet Explorer 6, which used to own a majority of the Web browser market share, is considered extremely insecure because vulnerabilities were commonly exploited due to its former popularity. Now, however, browser choice is more evenly distributed (Internet Explorer at 28.5%, Firefox at 18.4%, Google Chrome at 40.8%, and so on); vulnerabilities are commonly exploited in many browsers.

Buffer overflow attacks

A buffer overflow is an attack that could be used by a cracker to get full system access. Buffer overflow attacks are possible when an application that receives data from the network assumes, rather than checks, that the received data is short enough to be stored properly by the program. Most security applications and suites are incapable of adequate defense against these kinds of attacks.

Antivirus, anti-virus, or AV software is computer software used to prevent, detect and remove malicious computer viruses. Most software described as antivirus also works against other types of malware, such as malicious Browser Helper Objects (BHOs), browser hijackers, ransomware, keyloggers, backdoors, rootkits, trojan horses, worms, malicious LSPs, dialers, fraudtools, adware and spyware. Computer security, including protection from social engineering techniques, is commonly offered in products and services of antivirus software companies. This page discusses the software used for the prevention, detection, and removal of malwarethreats, rather than computer security implemented by software methods.

A variety of strategies are typically employed. Signature-based detection involves searching for known patterns of data within executable code. However, it is possible for a computer to be infected with new malware for which no signature is yet known; and malware is often modified to change its signature without affecting functionality. To counter such so-called zero-day threats, heuristics can be used. One type of heuristic approach, generic signatures, can identify variants by looking for slight variations of known malicious code in files. Some antivirus software can also predict what a file will do by running it in a sandbox and analyzing what it does to see if it performs any actions which could be malicious.

Antivirus software has some drawbacks. It can impair a computer's performance. Inexperienced users can be lulled into a false sense of security when using the computer, considering themselves to be totally protected, and may have problems understanding the prompts and decisions that antivirus software presents them with. An incorrect decision may lead to a security breach. If the antivirus software employs heuristic detection, it must be fine-tuned to minimise misidentifying harmless software as malicious (false positive). Antivirus software itself usually runs at the highly trusted kernel level of the operating system to allow it access to all potential malicious process and files, creating a potential avenue of attack.

 





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