The Dangers of Mobile Code

Because of the universal use of e-mail and world wide web, it is impossible for any security administrator to guarantee that no malicious external files, programs or data will reach the internal network. Primary culprits for web-based intrusions are applications using the Java and ActiveX programming languages. These languages allow Web sites to incorporate programs that users can run on their computers, in other words: remotely compiled programs are executed locally. It is not surprising that one should be rather nervous about executing untrusted code on one’s private network or machine.

Java
Java is a high-level, object-oriented, general-purpose programming language that took the Internet by storm, because it was one of the first technologies that could animate Web pages and make them interactive. Designed by Sun Microsystems in 1990, it is similar to C++, but it eliminates many language features that can cause common programming errors. Java source code files (files with a .java extension) are compiled into a format called byte code (files with a .class extension), which can then be executed by a Java interpreter. Java can be used to develop complete applications, called Java applets, which can perform a variety of tasks from the same Web page:

• Animations. 
• Games. 
• Charts. 
• Interactive programs. 

Let us see how this works in a Web browser on a desktop computer. References to Java software are embedded on a web page, which can be stored on a local disk or on the network. When the browser sees these references, it performs the following procedure:

• The Java software, i.e. the applet, is loaded. 
• The applet is then processed by the Java Virtual Machine (JVM), which is built into the browser. 
• This JVM does stringent security checks. 
• The JVM runs the applet, which appears and interoperates inside the browser. 
• The computer's operating system provides machine-specific support for many of the actual operations and interactions.

Threats to the home computers

A threat, for information security, is any activity that represents possible danger to user’s information. Intruders want the information stored by the users which are personal and sensitive, such as credit card numbers, PINs, passwords etc. By stealing this information the malicious intruders commonly referred to hackers may gain financially. The intruders also use the resources of the compromised systems for their own purposes and for attacking other computer systems connected to the Internet. Recent trends in computer security threats show that the attackers are compromising the home computers and installing malicious code such as Bots in these systems, which may then be used as Zombies to further launch large scale attacks on critical information systems. This type of attack is known as Distributed Denial of Service (DDOS).


Vulnerabilities in home computer
A vulnerability is a weakness in user’s information security that could be exploited by a threat; that is a weakness in user’s system and network security, processes, and procedures.

Computer vulnerability is flaw in the computer system. Which when exploited allows intruder to compromise the system’s integrity. The common types of vulnerabilities are logical errors in operating system or applications due to poor coding techniques, allowing intruder to exploit them and giving him heightened access to the user’s computer.

Various security tools are available to secure the system like firewalls etc. These tools provide excellent security mechanism but having flaw in design that could lead to security breach. The term “security through obscurity” fits into this arena, being the system is secure because nobody can see hidden elements. All types of file encryption come under this category. By means of encrypting the data an additional layer of protection is being added to the computer system.

In case a system is compromised, the critical data is still protected by encryption. And the intruder may not be able to steal the information from the hacked system.

Some Frequently Asked Questions about Computer Problems

Question 1: Why doesn’t my computer run as fast as it did when it was new? 

Answer: When you use your computer, you create files, install software, browse the Web and do a lot of other stuff. Windows works in such a way that pretty much everything you do creates temporary files and writes into the Windows registry. As time goes by, some registry entries become corrupted, temporary files don’t get deleted, and the list of programs launching on Windows boot grows. All this clutter makes your computer slow. 

Question 2: Why does the registry keep getting corrupted? 

Answer: The registry is a very complicated database that contains hundreds of entries. Every time you uninstall or update software, update your drivers, or even simply update Windows, registry entries are updated as well. Sometimes things go wrong and the registry gets updated incorrectly. As a result, some registry entries become corrupted or empty. A good registry cleaner can fix this. 

Question 3: How to get rid of unwanted bloatware? 

Answer: Getting rid of bloatware is easy you just need the right tools. To remove junk files and other debris, simply run disk cleanup, registry cleanup, remove unneeded startup entries, uninstall software you don’t use (like expired trial software), and finally use a duplicate file finder to get rid of duplicate files. 

Question 4: How do I make my PC boot faster? 

Answer: There are many ways to make your PC boot faster, but the easiest one is to remove unnecessary startup entries. You can use a startup manager to view the list of programs running on system startup and disable things like IM programs, toolbars, launchers, and players. 

Question 5: How to remove remnants of old programs that were uninstalled in the past? 

Answer: Leftovers from uninstalled programs are easy to remove. Just run a registry cleaner to get rid of empty keys and missing references and then go to your Program Files folder and remove empty folders (hover your mouse pointer over the folders and delete the ones that have 0 byte size).