Since one of our compatriots already shared Lesson 1 of my Computer Security 101 series I thought I would officially add the lessons to the Tutorials forum here on AO. However, due to copyright and legal restrictions I can't simply post the whole thing. I am going to post a big chunk of each lesson and then link back to my original article for those who wish to read the entire lesson at

With Lesson 8 we begin to enter the home stretch in the 10-part Computer Security 101 Series. The object of Computer Security 101 is to provide an introduction for new or novice users to the technology, terminology and acronyms commonly used with computers and networks.

Understanding these things better will hopefully help people understand what, how and why they need to secure their computers as well.
Lesson 7 was dedicated to hardware and software based firewalls. With Lesson 8 we will begin discussing preventive and proactive measures users can or should take to protect themselves from hacking, viruses and other malicious threats.

According to one security research firm there have been 28 vulnerabilities identified for the Windows XP Home operating system between January 1, 2003 and June 30, 2003. For Windows 2000 during that same time frame there were 32 vulnerabilities identified. Depending on the version of Linux you might be running there were up to 14 vulnerabilities identified.

The vulnerabilities mentioned above apply only to the operating system itself too. The Internet Explorer web browsing software had 20 vulnerabilities identified during the period from January 1, 2003 to June 30, 2003. There was 1 vulnerability identified for the Adobe Acrobat Reader software and 18 vulnerabilities identified for the popular Apache web server program.

The point of all of this is that if you haven’t been paying attention and applying patches as they become available for your system and applications you could be vulnerable to more attacks and exploits than you’d care to count.

Not all of these vulnerabilities are created equally. Many, if not most, are minor annoyances. The set of conditions necessary to actually exploit the vulnerability can be so specific and / or the potential damage from the vulnerability may be so minor that its hardly worth taking notice. But, every once in awhile a vulnerability comes along that, if properly exploited, can lead to the complete and total compromise of your computer system.

That means the attacker could potentially read, copy or delete any file on your system- personal information, financial information, family photos. They could also secretly place backdoors to allow them to continue getting into your system even if you do patch the vulnerability after the fact. Your system could have software installed that will allow the attacker to use your computer to initiate attacks on other computers.

Sometimes the exploitation of these vulnerabilities can be automated through a virus or worm. Most of the viruses and worms that have had significant impact on the Internet in the past few years actually took advantage of known vulnerabilities for which patches had been available for months.

Earlier this year the SQL Slammer worm generated so much traffic that it essentially brought the Internet to its knees for a weekend- the routers and servers that direct the flow of traffic could not handle the volume. SQL Slammer exploited a flaw in Microsoft’s SQL Server software for which a patch had been made available over 6 months prior. Unfortunately a good percentage of the SQL Servers in the world had not been patched. If they had SQL Slammer might have fizzled out and nobody would have even noticed it.

Why should you care? Many people believe they have no files or information of significant value or confidentiality on their PC’s so they have no reason to care if their computer gets hacked. As mentioned above though, leaving your system vulnerable could allow an attacker to hijack it and use it to attack other computers. It could also mean that your machine could end up propagating the next big virus or worm and infecting hundreds or thousands of other computers. As a member of the Internet-user community you have a responsibility (see False Sense of Security) to do what you can to keep the community secure even if you don’t care about protecting yourself.

Full Article: Computer Security 101: Lesson 8