Whether you’re a network administrator, use a computer at work, or just an average user who loves to browse the internet, then this simple and easy to understand information is for you.
The information shared here where taken from the eBook provided by SOPHOS. This will teach you facts about computer viruses, worms, spyware, spam – and more – in simple, easy-to-understand language.
Whether you use a Mac or a Pc, this will be useful information for you. You might use the computer daily or once in a blue moon– you never know when this information might come in handy. The next time you are sending an email or checking in or party bets, making hotel reservation or selling stuff online you will feel more confident and IT-fluent. Read more here below, and feel free to get in touch with your questions!
We are living in a digital world, were computers are not just an ordinary thing anymore but a “necessity” to our everyday lives. Most of us only knew a little about computer security threats, the most common were “virus” and “worm”. But did you know that there are 34 different types of Computer Security Threats? A lot huh? You’ll know more about them below, so keep reading and i hope that you’ll be more cautious and knowledgeable in using your computer.
1. Adware
Adware is software that displays advertisements on your computer.
Adware, or advertising-supported software, displays advertising banners or pop-ups on
your computer when you use the application. This is not necessarily a bad thing. Such
advertising can fund the development of useful software, which is then distributed free
(for example, the Opera web browser).
However, adware becomes a problem if it:
- installs itself on your computer without your consent
- installs itself in applications other than the one it came with and displays advertising
when you use those applications - hijacks your web browser in order to display more ads (see Browser hijackers)
- gathers data on your web browsing without your consent and sends it to others via
the internet (see Spyware) - is designed to be difficult to uninstall.
Adware can slow down your PC. It can also slow down your internet connection by
downloading advertisements. Sometimes programming flaws in the adware can make
your computer unstable.
Advertising pop-ups can also distract you and waste your time if they have to be closed
before you can continue using your PC.
Some anti-virus programs detect adware and report it as “potentially unwanted
applications”. You can then either authorize the adware program or remove it from the
computer. There are also dedicated programs for detecting adware.
2. Backdoor Trojans
A backdoor Trojan allows someone to take control of another user’s
computer via the internet without their permission.
A backdoor Trojan may pose as legitimate software, just as other Trojan horse programs
do, so that users run it. Alternatively – as is now increasingly common – users may
allow Trojans onto their computer by following a link in spam mail.
Once the Trojan is run, it adds itself to the computer’s startup routine. It can then
monitor the computer until the user is connected to the internet. When the computer
goes online, the person who sent the Trojan can perform many actions – for example,
run programs on the infected computer, access personal files, modify and upload files,
track the user’s keystrokes, or send out spam mail.
Well-known backdoor Trojans include Subseven, BackOrifice and, more recently,
Graybird, which was disguised as a fix for the notorious Blaster worm.
To avoid backdoor Trojans, you should keep your computers up to date with the latest
patches (to close down vulnerabilities in the operating system), and run anti-spam
and anti-virus software. You should also run a firewall, which can prevent Trojans from
accessing the internet to make contact with the hacker.
3. Bluejacking
Bluejacking is sending anonymous, unwanted messages to other users
with Bluetooth-enabled mobile phones or laptops.
Bluejacking depends on the ability of Bluetooth phones to detect and contact other
Bluetooth devices nearby. The Bluejacker uses a feature originally intended for
exchanging contact details or “electronic business cards”. He or she adds a new entry
in the phone’s address book, types in a message, and chooses to send it via Bluetooth.
The phone searches for other Bluetooth phones and, if it fi nds one, sends the message.
Despite its name, Bluejacking is essentially harmless. The Bluejacker does not steal
personal information or take control of your phone.
Bluejacking can be a problem if it is used to send obscene or threatening messages or
images, or to send advertising. If you want to avoid such messages, you can turn off
Bluetooth, or set it to “undiscoverable”.
Bluetooth-enabled devices may also be at risk from the more serious Bluesnarfing.
4. Bluesnarfing
Bluesnarfing is the theft of data from a Bluetooth phone.
Like Bluejacking, Bluesnarfing depends on the ability of Bluetooth-enabled devices to
detect and contact others nearby.
In theory, a Bluetooth user running the right software on their laptop can discover a
nearby phone, connect to it without your confirmation, and download your phonebook,
pictures of contacts and calendar.
Your mobile phone’s serial number can also be downloaded and used to clone the
phone.
You should turn off Bluetooth or set it to “undiscoverable”. The undiscoverable setting
allows you to continue using Bluetooth products like headsets, but means that your
phone is not visible to others.
5. Boot Sector Viruses
Boot sector viruses spread by modifying the program that enables your
computer to start up.
When you switch on a computer, the hardware looks for the boot sector program –
which is usually on the hard disk, but can be on a floppy disk or CD – and runs it. This
program then loads the rest of the operating system into memory.
A boot sector virus replaces the original boot sector with its own, modified version (and
usually hides the original somewhere else on the hard disk). When you next start up,
the infected boot sector is used and the virus becomes active.
You can only become infected if you boot up your computer from an infected disk, e.g.
a floppy disk that has an infected boot sector.
Boot sector viruses were the first type of virus to appear, and they are mostly quite old.
They are rarely encountered today.
6. Browser Hijackers
Browser hijackers change the default home and search pages in your
internet browser.
Some websites run a script that changes the settings in your browser without your
permission. This hijacker can add shortcuts to your “Favorites” folder or, more seriously,
can change the page that is first displayed when you open the browser.
You may find that you cannot change your browser’s start page back to your chosen
site. Some hijackers edit the Windows registry so that the hijacked settings are restored
every time you restart your computer. Others remove options from the browser’s tools
menu, so that you can’t reset the start page.
In every case, the intention is the same: to force you to visit a website. This inflates
the number of “hits” and the site’s ranking with search engines, which boosts the
advertising revenue that the site can earn.
Browser hijackers can be very tenacious. Some can be removed automatically by
security software. Others may need to be removed manually. In some cases, it is easier
to restore the computer to an earlier state or reinstall the operating system.
7. Chain Letters
An electronic chain letter is an email that urges you to forward copies
to other people.
Chain letters, like virus hoaxes, depend on you, rather than on computer code, to
propagate themselves. The main types are:
- Hoaxes about terrorist attacks, premium-rate phone line scams, thefts from ATMs
and so forth. - False claims that companies are offering free flights, free mobile phones, or cash
rewards if you forward email. - Messages, which purport to be from agencies like the CIA and FBI, warning about
dangerous criminals in your area. - Petitions. Even if genuine, they continue to circulate long after their expiry date.
- Jokes and pranks, e.g. the claim that the internet would be closed for maintenance
on 1 April.
Chain letters don’t threaten your security, but they can waste time, spread
misinformation and distract users from genuine email.
They can also create unnecessary email traffic and slow down mail servers. In some
cases the chain letter encourages people to send email to certain addresses, so that
these are deluged with unsolicited mail.
The solution to the chain letter problem is simple: don’t forward such mail.
8. Cookies
Cookies are files on your computer that enable websites to remember
your details.
When you visit a website, it can place a fi le called a cookie on your computer. This
enables the website to remember your details and track your visits. Cookies can be a
threat to confidentiality, but not to your data.
Cookies were designed to be helpful. For example, if you submit your ID when you visit
a website, a cookie can store this data, so that you don’t have to re-enter it next time.
Cookies also have benefits for webmasters, as they show which web pages are well used,
providing useful input when planning a redesign of the site.
Cookies are small text files and cannot harm your data. However, they can compromise
your confidentiality. Cookies can be stored on your computer without your knowledge or
consent, and they contain information about you in a form you can’t access easily. And
when you revisit the same website, this data is passed back to the web server, again
without your consent.
Websites gradually build up a profile of your browsing behavior and interests. This
information can be sold or shared with other sites, allowing advertisers to match ads
to your interests, ensure that consecutive ads are displayed as you visit different sites,
and track the number of times you have seen an ad.
If you prefer to remain anonymous, use the security settings on your internet browser to
disable cookies.
9. Denial of Service attack (DoS)
A denial-of-service (DoS) attack prevents users from accessing a computer or website.
In a DoS attack, a hacker attempts to overload or shut down a computer, so that
legitimate users can no longer access it. Typical DoS attacks target web servers
and aim to make websites unavailable. No data is stolen or compromised, but the
interruption to the service can be costly for a company.
The most common type of DoS attack involves sending more traffic to a computer than
it can handle. Rudimentary methods include sending outsized data packets or sending
email attachments with names that are longer than permitted by the mail programs.
An attack can also exploit the way that a “session” of communications is established
when a user first contacts the computer. If the hacker sends many requests for a
connection rapidly and then fails to respond to the reply, the bogus requests are left in
a buffer for a while. Genuine users’ requests cannot be processed, so that they can’t
contact the computer.
Another method is to send an “IP ping” message (message requiring a response from
other computers) that appears to come from the victim’s computer. The message goes
out to a large number of computers, which all try to respond. The victim is flooded with
replies and the computer can no longer handle genuine traffic.
A distributed denial-of-service (DDoS) attack uses numerous computers to launch the attack. Typically, hackers use a virus or Trojan to open a “back door” on other people’s
computers and take control of them. These “zombie” computers can be used to launch
a coordinated denial-of-service attack.
10. Dialers
Dialers change the number used for dial-up internet access to a premium-rate number.
Dialers are not always malicious. Legitimate companies that offer downloads or games
may expect you to use a premium-rate line to access their services. A pop-up prompts
you to download the dialer and tells you how much calls will cost.
Other dialers may install themselves without your knowledge when you click on a
pop-up message (for example, a message warning you about a virus on your computer
and offering a solution). These do not offer access to any special services – they simply
divert your connection so that you access the internet via a premium-rate number.
Broadband users are usually safe, even if a dialer installs itself. This is because
broadband doesn’t use regular phone numbers, and because broadband users don’t
usually have a dial-up modem connected.
Anti-virus software can detect and eliminate Trojan horse programs that install dialers.
11. Document Viruses
Document or “macro” viruses take advantage of macros – commands that are embedded in fi les and run automatically.
Many applications, such as word processing and spreadsheet programs, use macros.
A macro virus is a macro program that can copy itself and spread from one file to
another. If you open a file that contains a macro virus, the virus copies itself into the
application’s startup files. The computer is now infected.
When you next open a file using the same application, the virus infects that file. If your
computer is on a network, the infection can spread rapidly: when you send an infected
file to someone else, they can become infected too. A malicious macro can also make
changes to your documents or settings.
Macro viruses infect files used in most offices and some can infect several file types,
such as Word and Excel files. They can also spread to any platform on which their host
application runs.
Macro viruses first appeared in the mid-1990s and rapidly became the most serious
virus threat of that time. Few viruses of this type are seen now.
