Whether you need IT support, software support, or hardware service, we've got you covered so you can get back to business. No devices were immune to these infections—not even mobile devices. What is malware? Malicious software, or " malware," is software written with the intent to damage, exploit, or disable devices, systems, and networks. It is used to compromise device functions, steal data, bypass access controls, and cause harm to computers and other devices and the networks they are connected to.
According to a recent Internet Security Threat Report by Symantec, there were million new malware variants discovered in , and the percentage of groups using malware is on the rise, too.
The six most common types of malware are viruses, worms, Trojan Horses, spyware, adware, and ransomware. Learn more about these common types of malware and how they spread:.
Viruses are designed to damage the target computer or device by corrupting data, reformatting your hard disk, or completely shutting down your system. They can also be used to steal information, harm computers and networks, create botnets, steal money, render advertisements, and more. Computer viruses require human action to infect computers and mobile devices and are often spread through email attachments and internet downloads.
One of the most common types of malware, worms spread over computer networks by exploiting operating system vulnerabilities. A worm is a standalone program that replicates itself to infect other computers, without requiring action from anyone. Since they can spread fast, worms are often used to execute a payload—a piece of code created to damage a system. Payloads can delete files on a host system, encrypt data for a ransomware attack, steal information, delete files, and create botnets.
As soon as you install a Trojan, you are giving cyber criminals access to your system. Through the Trojan horse, the cyber criminal can steal data, install more malware, modify files, monitor user activity, destroy data, steal financial information, conduct denial of service DoS attacks on targeted web addresses, and more.
As we saw in the first week of the course, phishing can sometimes be targeted at individuals or specific parts of an organisation. For example, an attacker might use information gleaned from recent emails to craft a plausible reply that appears to come from colleagues of the targeted user.
Attackers may also include links to malware-infected software in personal messages posted in social media. This is especially common after major disasters or during fast-breaking news when people are likely to click on interesting looking links without thinking carefully. Phishing is just one type of spam email which clutters our mailboxes and often delivers unsuitable or even illegal content to individuals. Spam is yet another consequence of the early internet being developed by people who trusted one another.
Most internet email is moved around the world using the Simple Mail Transfer Protocol SMTP which defines a standard template of commands and formatting that allow different mail programs, on a huge range of computers, to understand one another.
Protocols are used to specify a set of special messages that should be exchanged between computers to achieve a particular functionality, in this case the delivery of email. SMTP was defined when the internet had only a tiny number of users, so the original specification did not include any way for computers to authenticate one another, i. Since SMTP servers do not perform any authentication, they simply pass on the email without checking that it was sent out by TrustedBank.
Provided a spammer has access to a fast network or increasingly to a botnet , spam costs the sender almost nothing and although only a tiny fraction of users will respond to a spam message, sufficiently vast numbers of emails are sent that the rewards far outweigh the costs. Such is the torrent of spam that internet service providers and companies have to buy far more bandwidth and storage than they will ever need for legitimate purposes.
Although a phishing attack may appear plausible at first glance, there are some tell-tale signs that should make you very cautious about clicking on any links or giving any personal information to the supposed sender.
Spelling mistakes : Most English-language phishing expeditions are sent from countries where English is not the primary language. Attackers often give themselves away by imprecise use of English, even with quite common phrases, and including spelling errors. So read the message carefully. However, there are many phishing emails that use excellent English. Who is it to? This is because they cannot personalise the emails sufficiently.
However, note that because so many millions of user details have been revealed by data breaches it is quite possible for a phishing email to use your personal details.
Poor quality images : Sometimes, the images used in the emails are fuzzy, or your information may appear as an image rather than type. These images have been copied from screens and would not be used by original companies. It is easy to obtain images every bit as good as the originals though, so a high quality image should not persuade you the message is genuine.
Content of the email : In almost all countries, banks and other financial bodies will not email you to tell you about problems with your account. They recognise that email is fundamentally insecure and that personal information should not be sent by email. The email may give a false sense of urgency, claiming that your account is at risk if you do not act quickly.
This is not the case. You can spot some fake links by hovering your mouse pointer over the link — but do not click the button. The actual destination of the link will appear at the bottom of the window or in a small floating window next to the link. Other fake links may display a genuine destination when you hover over them, but still take you to a fake website because code in the page intercepts the link and sends your click elsewhere. The example message below claims to come from a fictional site called ePay and is about unauthorised activity on the account.
So the rules are to be suspicious and to look at the details of the message, the language, the quality of the images and where the links actually take you. Banks and shops will always prefer you to call them and check rather than risking your security. Email addresses that are on a breached list are much more likely to receive spam than those that are not listed. If your email address is on the list you need to assess what related data may have been revealed.
You may need to change passwords that use that email address, especially if you have reused the same passwords in the past, or even stop using that email address. Malware will be spread through any means possible.
Malware can be distributed by including it with pirated material such as illegal copies of software, video games and movies. Once it is on a machine running social networking software, the malware masquerades as the real user and posts messages containing links to sites that distribute yet more malware. Once again, this type of malware relies on social engineering to multiply — users of social networks are highly likely to click on links they think have come from friends and spread the infection.
Most of these social networking infections have exploited weaknesses in client software rather than the web versions of the networks, so it is important to keep social networking client software, such as the Facebook App for mobile devices, up to date.
As you will have seen, many large websites rely on advertising for their revenue. Advertisers like online advertising because it can be relatively cheap compared to a printed advertisement and because software allows for individuals to be targeted with specific adverts for products they are likely to buy.
Computers all around the world, operating as a botnet, can generate false clicks, siphoning money from advertisers through multiple layers of publishers and redistributors to hide its eventual destination. There are two frequently used modes of click fraud — both can use botnets to generate the clicks.
While an individual click will only raise a tiny amount of money, done millions of times, click fraud can raise serious amounts of money.
In , a Russian criminal group created 6, websites with over , pages containing video advertising. They were defrauding the advertisers of close to four million dollars a day.
You heard about botnets briefly in Week 1, when we said that botnets are created using malware that give an attacker control over a group of computers and commonly use them to gather information from the computers e. These attacks might be sending spam emails, or flooding a website with so many requests for content that the server cannot cope, which is known as a denial-of-service attack. A single piece of malware can cause enormous damage, but when thousands, or even millions of computers run the same program, their effects can be devastating.
So a botnet is a group of computers that coordinate their activity over the internet. There are a number of harmless botnets used for such purposes as the Internet Relay Chat IRC text messaging program, but the vast majority are created by malware. At this point, the infected computer often called a zombie will do nothing more except periodically check for instructions from the control computer. At some point in the future, the control computer will issue a command for the botnet to wake up and begin doing something.
Often the people who created the botnet itself have either sold or rented the botnet to another group who want to use its capabilities. Botnets have been used to flood the internet with spam messages, to commit fraud against advertisers and to perform so-called distributed denial-of-service attacks on companies and governments.
Botnets are so large, and so widely distributed across the internet that they can be very hard to tackle and the effects of a coordinated attack on critical parts of the network can mean even very large websites struggle to remain online while the botnet targets their computers. If you discuss this with others, remember not to share any personal information including the name of the company you work for.
The growth in malware has been accompanied by an explosive growth in software designed to prevent it spreading. So-called antivirus software which actually targets a range of malware is a multi-billion pound business with a large number of commercial and free packages available for all computer users ranging from individuals to large corporations. At the same time, the developers of computer operating systems are incorporating a wider range of security features that try to stop malware running at all.
And there is a lot you can do yourself to keep yourself protected such as installing antivirus software, keeping your software up to date, looking out for the signs of phishing emails and implementing new security developments. Before you install or change anti-malware software you should check the reviews from a number of reputable and independent organisations. Look at how they rate the free packages as well as the paid for packages.
Antivirus software aims to detect, isolate and if necessary, delete malware on a computer before it can harm data. Antivirus software uses several techniques to identify malware — the two most common are known as signatures and heuristics. It is not uncommon for several variants of a malware program to be published at intervals, each sufficiently different that they possess different signatures.
A second weakness of signatures is that more sophisticated malware has the ability to change its program it is said to be polymorphic or metamorphic , disguising itself without affecting its operation. Complementing signatures, heuristics use rules to identify viruses based on previous experience of the behaviour of known viruses.
Heuristic detection may execute suspicious programs in a virtual machine a software recreation of a physical computer and analyse the program for operations typical of known malware such as replicating itself or attempting to overwrite key operating system files ; or it might revert the program back to its original source code and look for malware-like instructions.
If the heuristic analysis considers that the file acts in a malware-like manner, it is flagged as potentially dangerous. Unlike signatures, heuristics do not require specific knowledge about individual types of malware — they can detect new malware, for which signatures do not exist, simply by their behaviour. The drawback of heuristics is that they can only draw conclusions based on past experience; radically new malware which appears all too regularly can pass unnoticed.
Although antivirus software is an essential part of protecting your computer, it is not a complete solution to malware problems. Despite the best endeavours of its makers, antivirus software has occasionally proved to contain bugs with consequences like being inaccurate, failing to update itself or simply consuming huge amounts of computer power. Fortunately, these problems are rare, easily fixed and much less serious than the risk from a malware attack.
Note that not all anti-malware software is equally good. There is even fake anti-malware offered for sale, especially for mobile devices. In October , the BBC reported that a combined operation by British Police, Indian police and Microsoft had shut down two Indian call centres using web pages and phone calls to sell fake computer security services.
Please log in and verify recent charges. Click here to run a scan. Malware can also be disguised as a program or app that claims to convert PDFs, unzip files, find product discounts or provide caller ID functionality on a smartphone. But once the program is downloaded, it begins making unauthorized changes on the system: monitoring user behavior, displaying pop-ups, changing search engine results, adding icons to a desktop or redirecting popular sites.
Malware can be delivered in several different forms, depending on the intention of the person who developed it. Ransomware is a form of malware that locks a user's computer and then demands a ransom payment to restore access. Ransomware can be delivered to a computer if a user clicks on a link that contains malware. Phishing involves a scammer sending emails that can appear harmless and typically ask the recipient to click a link or download a file.
These messages look like they're from a legitimate, trustworthy source, but once the recipient clicks or downloads, the hacker gains access to the user's computer.
Ransomware often begins as a phishing attack, but it goes a step further in inciting panic that may urge users to quickly take the hacker's desired action. Once a user has clicked a link or file for download, the ransomware freezes their computer. It then attempts to blackmail the user into paying money for the scammer to return the user's stolen personal information. This form of malware relies on fear—that is, the fear that a user has engaged in illegal activity online.
By posing as a law enforcement agency, a ransomware purveyor can intimidate and coerce a user while seeming legitimate. In other instances, ransomware will simply lock down a user's entire machine, including important files and programs, and demand a payment.
Ransomware may not only withhold access to a machine, but also threaten to delete files unless payment is made. Not all malware is as obvious as ransomware.
In fact, some malware runs almost silently in the background of your device. Here are several signs that you may have fallen victim to malware:. If you suspect malware is active on your device, disconnect it from the internet and take steps to remove the malicious software.
Find instructions from a trusted source, such as a well-known technology service provider.
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