.: Computer security
.: Technical security precautions details how you can secure your personal computer
Note: Following some of the suggestions below can affect how your computer interacts with the network. If your computer or local network is managed by a computer support provider, you should consult with your provider before making changes to avoid disrupting your network connection.
Top three things you can do to protect your computer
Use security software
The most important thing you can do to keep your computer safe is to install and maintain security software, which protects your computer from viruses and spyware. Such security programs perform two general functions: scanning for and removing viruses and spyware in files on disks, and monitoring the operation of your computer for virus-like activity (either known actions of specific viruses or general suspicious activity). Most software can perform both of these tasks.
Install an antivirus application, and keep your virus pattern files up to date.
Kaspersky Anti-Virus 2012
In general, it's not a good idea to have more than one antivirus program installed on your computer. Each program may interpret the actions of the other as viral, therefore giving you false warnings about virus-related activities.
For antispyware for Windows computers, we use Spybot Search and Destroy and Windows Defender. There are other product, first consult with a professional before installing software on your PC.
Install and run Identity Finder, a tool to help you search for, protect, and dispose of personal information stored on your computer, file shares, or external media.
Install the Secunia Personal Software Inspector. This will alert you when your current software applications are out of date or require a security update.
Practice the principle of least privilege (PoLP)
Practice the principle of least privilege. Do not enable administrative privileges until needed (i.e., do not log into a computer with administrative rights unless you must do so to perform specific tasks). Running your computer as an administrator (or as a Power User in Windows) leaves your computer vulnerable to security risks and exploits. Simply visiting an unfamiliar Internet site with these high-privilege accounts can cause extreme damage to your computer, such as reformatting your hard drive, deleting all your files, and creating a new user account with administrative access. When you do need to perform tasks as an administrator, always follow secure procedures.
Maintain current software and updates
Keep your software updated by applying the latest service packs and patches. For Windows, you can schedule Automatic Updates to automatically download and install available updates.
The best way to maintain third-party software is to install the Secunia Personal Software Inspector. This will alert you when your current software applications are out of date or require a security update.
Avoiding threats to your computer
Never share passwords or pass phrases: Pick strong passwords and pass phrases, and keep them private. Never share your passwords or pass phrases, even with friends, family, or computer support personnel.
Do not click random links: Do not click any link that you can't verify. To avoid viruses spread via e-mail or instant messaging (IM), think before you click; if you receive a message out of the blue, with nothing more than a link and/or general text, do not click it.
Beware of e-mail or attachments from unknown people, or with a strange subject line.
Computer security risks to home users
What is at risk?
Information security is concerned with three main areas:
- Confidentiality - information should be available only to those who rightfully have access to it
- Integrity -- information should be modified only by those who are authorized to do so
- Availability -- information should be accessible to those who need it when they need i
These concepts apply to home Internet users just as much as they would to any corporate or government network. You probably wouldn't let a stranger look through your important documents. In the same way, you may want to keep the tasks you perform on your computer confidential, whether it's tracking your investments or sending email messages to family and friends. Also, you should have some assurance that the information you enter into your computer remains intact and is available when you need it.
Some security risks arise from the possibility of intentional misuse of your computer by intruders via the Internet. Others are risks that you would face even if you weren't connected to the Internet (e.g. hard disk failures, theft, power outages). The bad news is that you probably cannot plan for every possible risk. The good news is that you can take some simple steps to reduce the chance that you'll be affected by the most common threats -- and some of those steps help with both the intentional and accidental risks you're likely to face.
Before we get to what you can do to protect your computer or home network, let’s take a closer look at some of these risks.
Intentional misuse of your computer
The most common methods used by intruders to gain control of home computers are briefly described below.
Trojan horse - These programs are a common way for intruders to trick you (sometimes referred to as "social engineering") into installing "back door" programs. These can allow intruders easy access to your computer without your knowledge, change your system configurations, or infect your computer with a computer virus. More information about Trojan horses can be found in the following document.
Back door and remote administration programs - On Windows computers, three tools commonly used by intruders to gain remote access to your computer are BackOrifice, Netbus, and SubSeven. These back door or remote administration programs, once installed, allow other people to access and control your computer.
Denial of service - Another form of attack is called a denial-of-service (DoS) attack. This type of attack causes your computer to crash or to become so busy processing data that you are unable to use it. In most cases, the latest patches will prevent the attack.
It is important to note that in addition to being the target of a DoS attack, it is possible for your computer to be used as a participant in a denial-of-service attack on another system.
Being an intermediary for another attack, Intruders will frequently use compromised computers as launching pads for attacking other systems. An example of this is how distributed denial-of-service (DDoS) tools are used. The intruders install an "agent" (frequently through a Trojan horse program) that runs on the compromised computer awaiting further instructions. Then, when a number of agents are running on different computers, a single "handler" can instruct all of them to launch a denial-of-service attack on another system. Thus, the end target of the attack is not your own computer, but someone else’s -- your computer is just a convenient tool in a larger attack.
Unprotected Windows shares - Unprotected Windows networking shares can be exploited by intruders in an automated way to place tools on large numbers of Windows-based computers attached to the Internet. Because site security on the Internet is interdependent, a compromised computer not only creates problems for the computer's owner, but it is also a threat to other sites on the Internet. The greater immediate risk to the Internet community is the potentially large number of computers attached to the Internet with unprotected Windows networking shares combined with distributed attack tools.
Another threat includes malicious and destructive code, such as viruses or worms, which leverage unprotected Windows networking shares to propagate. There is great potential for the emergence of other intruder tools that leverage unprotected Windows networking shares on a widespread basis.
Cross-site scripting - A malicious web developer may attach a script to something sent to a web site, such as a URL, an element in a form, or a database inquiry. Later, when the web site responds to you, the malicious script is transferred to your browser.
You can potentially expose your web browser to malicious scripts by
- following links in web pages, email messages, or newsgroup postings without knowing what they link to
- using interactive forms on an untrustworthy site
- viewing online discussion groups, forums, or other dynamically generated pages where users can post text containing HTML tags
Email spoofing - Email “spoofing” is when an email message appears to have originated from one source when it actually was sent from another source. Email spoofing is often an attempt to trick the user into making a damaging statement or releasing sensitive information (such as passwords).
Spoofed email can range from harmless pranks to social engineering ploys. Examples of the latter include;
email claiming to be from a system administrator requesting users to change their passwords to a specified string and threatening to suspend their account if they do not comply, or email claiming to be from a person in authority requesting users to send them a copy of a password file or other sensitive information.
Note that while service providers may occasionally request that you change your password, they usually willnot specify what you should change it to. Also, most legitimate service providers would never ask you to send them any password information via email. If you suspect that you may have received a spoofed email from someone with malicious intent, you should contact your service provider's support personnel immediately.
Email borne viruses - Viruses and other types of malicious code are often spread as attachments to email messages. Before opening any attachments, be sure you know the source of the attachment. It is not enough that the mail originated from an address you recognize. The Melissa virus spread precisely because it originated from a familiar address. Also, malicious code might be distributed in amusing or enticing programs.
Many recent viruses use these social engineering techniques to spread. Examples include,
W32/Sircam and the W32/Goner.
Never run a program unless you know it to be authored by a person or company that you trust. Also, don't send programs of unknown origin to your friends or coworkers simply because they are amusing -- they might contain a Trojan horse program.
Hidden file extensions - Windows operating systems contain an option to "Hide file extensions for known file types". The option is enabled by default, but a user may choose to disable this option in order to have file extensions displayed by Windows. Multiple email-borne viruses are known to exploit hidden file extensions. The first major attack that took advantage of a hidden file extension was the VBS/LoveLetter worm which contained an email attachment named "LOVE-LETTER-FOR-YOU.TXT.vbs". Other malicious programs have since incorporated similar naming schemes.
- Downloader (MySis.avi.exe or QuickFlick.mpg.exe)
- VBS/Timofonica (TIMOFONICA.TXT.vbs)
- VBS/CoolNote (COOL_NOTEPAD_DEMO.TXT.vbs)
- VBS/OnTheFly (AnnaKournikova.jpg.vbs)
The files attached to the email messages sent by these viruses may appear to be harmless text (.txt), MPEG (.mpg), AVI (.avi) or other file types when in fact the file is a malicious script or executable (.vbs or .exe, for example).
Chat clients - Internet chat applications, such as instant messaging applications and Internet Relay Chat (IRC) networks, provide a mechanism for information to be transmitted bi-directionally between computers on the Internet. Chat clients provide groups of individuals with the means to exchange dialog, web URLs, and in many cases, files of any type.
Because many chat clients allow for the exchange of executable code, they present risks similar to those of email clients. As with email clients, care should be taken to limit the chat client’s ability to execute downloaded files. As always, you should be wary of exchanging files with unknown parties.
Packet sniffing - A packet sniffer is a program that captures data from information packets as they travel over the network. That data may include user names, passwords, and proprietary information that travels over the network in clear text. With perhaps hundreds or thousands of passwords captured by the packet sniffer, intruders can launch widespread attacks on systems. Installing a packet sniffer does not necessarily require administrator-level access.
Relative to DSL and traditional dial-up users, cable modem users have a higher risk of exposure to packet sniffers since entire neighborhoods of cable modem users are effectively part of the same LAN. A packet sniffer installed on any cable modem user's computer in a neighborhood may be able to capture data transmitted by any other cable modem in the same neighborhood.
Do not download unfamiliar software off the Internet: KaZaA, Bonzi, Gator, HotBar, WhenUSave, CommentCursor, WebHancer, LimeWire, and other Gnutella programs all appear to have useful and legitimate functions.
(You have heard the phrase nothing is free, or if it sounds too good to be true.)
Most of this software is (or contains) spyware, which will damage your operating system installation, waste resources, generate pop-up ads, and report your personal information back to the company that provides the software.
Note: Before you choose to download and use these types of programs, make sure you are not violating copyright or other applicable laws. Downloading or distributing whole copies of copyrighted material for personal use or entertainment without explicit permission from the copyright owner is against the law.
Log out of or lock your computer when stepping away, even for a moment: Forgetting to log out poses a security risk with any computer that is accessible to other people (including computers in public facilities, offices, and shared housing), because it leaves your account open to abuse. Someone could sit down at that computer and continue working from your account, doing damage to your files, retrieving personal information, or using your account to perform malicious actions. To avoid misuse by others, remember to log out of or lock your computer whenever you leave it.
Remove unnecessary programs or services from your computer.
Restrict remote access: Disable file and print sharing. In rare exceptions when you may need to share a resource with others, you should format your drive using NTFS, and correctly set the file and directory permissions. With Windows 2000 and XP, new folders are created by default with access granted to the "everyone" group. If you do have file sharing enabled on your computer, be careful to set permissions correctly when creating new folders so you don't inadvertently leave them open to everyone.
Frequently back up important documents and files: This protects your data in the event of an operating system crash, hardware failure, or virus attack. Saving files in multiple places using two different forms of media (e.g., Carbonite, USB flash drive, or DVD).
Remove data securely: Remove files or data you no longer need to prevent unauthorized access to them. Merely deleting sensitive material is not sufficient, as it does not actually remove the data from your system. Use a secure file shredder or similar program.
Deploy encryption wherever it is available.