Cell Phone Virus
Labels: Cell Phone Virus
Who Needs Anti-Virus?
1.) Do not trust email (even if it's from a familiar email address)
Email addresses can easily be spoofed. All one needs is a widely available smtp server. The best way to avoid a problem here is to be aware of discrepancies in writing patters. If you aunt Lori writes to you ' Duuuddeee! You gotta check this out! Execute this shady file~' it's safe to assume that she is not the author -it may be her email address though.
2.) Do not open executable files (if you don't know the extension, don't execute it)
Viruses can infect an array of files in order to spread. The most common are *.exe, *.com, or *.vbs (love-bug). Think about it. Who sends you executable files? If a coworker, or someone else you trust, sends you an important executable file and urges you to open it. Just contact him/her on your cell phone to ensure he/she is the real author.
3.) Keep you OS state of the art
Many are tempted to simply update their anti-virus software. This creates a false sense of security. However, disregarding other important updates may prove costly. Most viruses target exploits in browsers and the OS system. If you are using Windows, it is extremely easy to update your system. Simply browse to www.windowsupdate.microsoft.com and follow the detailed instructions.
If you follow these steps and commit to updating your software and your knowledge about current threats, your expensive anti-virus software will be reduces to the last line of defense.
Labels: Who Needs Anti-Virus?
Types of Computer Viruses
Types of computer viruses:
Encrypted Viruses:
Perhaps the first measure virus authors took, in order to make their viruses harder to detect, was to encrypt the part of the code that the anti-virus software recognizes as a virus. Most viruses are programmed in a programming language that allows them to encrypt certain sections of the code.To illustrate this concept let's look at the following depiction:
Decryption Code
XXXXXXXXXX
XVirus CodeX
XXXXXXXXXX
The area marked with the X's would be encrypted. So if a anti virus software scans this file it will only scan the Decryption code, which will not be recognized as a virus. Lets look at this idea applied in a batch code:
set h=1
set e=2
set l=3
set o=4
set w=5
set r=6
set d=7
cls
echo %1%%2%%3%%3%%4% %5%%4%%6%3%%7%
pause
If executed, the code would prompt a message stating 'hello world'. Of course, the part that contains the message could be a virus code. A anti-virus scanner would not be able to tell the difference.
Marcro Viruses:
These viruses are a rather moder phenomenon. They use commonly used programs like Microsoft Word, or Excel and embed themselves in these files. Once a user executes, these files the virus will activate itself and run the malicious code. The pinnacle of the macro virus era was when the infamous Melissa Virus went around the world. This particular virus was embedded in a Word file and would spread very rapidly utilizing a bug in Microsoft Outlook. Unfortunately, batch is not applicable to such an idea, as the virus has to be part of the program it exploits.
Polymorphic Viruses:
These viruses have posed a great threat to internet security, given that it was practically impossible to detect them at the time. They consistently change the body of their code making detection very difficult. Even today, many viruses include poly engines - snippets of code that change the code around. The simplest manner to understand this idea is to look at the following code (modified batch code):
replace XX in code with Randomnumber
set h=XX1
set e=XX2
set l=XX3
set o=XX4
set w=XX5
set r=XX6
set d=XX7
cls
echo %XX1%%XX2%%XX3%%XX3%%XX4% %XX5%%XX4%%XX6%XX3%%XX7%
pause
We see that each time the code is executed the XX part of the code will be replaced with a random number. After it is executed once, it will search for a particular random number and replace it with another random number ect. Hence, it is very difficult to write a code that will be able to detect this type of virus. Certainty, it is possible to make the code much more complex as the one above. Here, it only severs as an example.
Stealth Viruses:
Viruses of this breed attempt to hide themselves from a virus scanner by employing known exploits in the OS or other commonly used programs. Let's for instance assume that it is know that a anti virus scanner does not check files that are located in the directory of the anti virus software. Hence, a virus could copy itself to this particular location and be undetected by the virus scanner. There is also memory stealth viruses but these viruses have been outdated and are no longer of concern.
It is safe to assume that as long as there are virus writers there will be new methods they will exploit. However, the current trend is to use multiple methods, new and old, in oder not to be detected. Once people have an idea of the main methods at use, they can better prepare themselves for a virus attack.
Labels: Types of Computer Viruses
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