As internet users we are all aware of the infections that are caused to our systems. We call each infections a set of medical terms like viruses,worms etc. so at some point of time we may even say my computer has caught a flue while browsing , just kidding . All apart we always trust on antivirus and some software to treat these viruses as doctors. My agenda here is to let a light pass though everyones mind so that they could understand what are these viruses and infections that we are dealing with.
Fist of all how could we know that our system is infected, for starters just ask someone whose system has been compromised. They will advice you not even to think about it as it’s very difficult to return a compromised system back to normal.There are certain common symptoms for infected system i would like to suggest a few. Let’s see:
1. Some times your computer behaves strangely, i.e. in a way that you havent seen before.
2. Unexpected messages or images will popup on your screen.
3. Unexpected sounds are played all of a sudden like some ghost ran into the system, Programs start
unexpectedly.
4. Firewall tells you that an application has tried to connect to the Internet (and its not a program
that you ran).
5. Your computer freezes frequently, or programs start running slowly.
6. System is automatically filling with error messages.
7. The operating system will not load when you start your computer.
8. The files or folders in your computer have been deleted or changed.
9. The web browser behaves erratically, e.g. you cant close a browser window.
This is general outline only, different infections have different effects on the computer. Lets move on to the next step what are different infections that are caused on the computer.
Back doors, sometimes called trap doors, allow unauthorized access to your system.An attackers often use back doors that they detect or install themselves, as part of an exploit. In some cases, a worm is designed to take advantage of a back door created by an earlier attack.
Logic bombs are programmed threats that lie dormant for an extended period of time until they are triggered; at this point, they perform a function that is not the intended function of the program in which they are contained. Logic bombs usually are embedded in programs by software developers who have legitimate access to the system.These bombs are so carefully added so that the software will be performing its nor purpose for the time being but it will get into action when the specified condition set by the attacker meets.
Viruses are “programs” that modify other programs on a computer, inserting copies of themselves. A program is a file that adheres to a strict description of how its content is organized. On Linux systems, the ELF document of some 50-pages describes this format. In this sense, viruses are not programs – they cannot run on their own, and need to become part of some host program. When such an infected program is executed, the virus attaches itself to another and so on.
A worm is a malicious program that copies itself from one computer to another on a network. A worm is an independent program, unlike a virus which is a part-program that must insert itself into a whole-program. A worm typically does not modify other programs. A typical worm may carry other code, including programs and viruses.
Trojan horses are programs that appear to have one function but actually perform another function. Trojan horses are named after the Trojan horse of the Greek Trojan War.These are typically used for data theft, information theft, identity theft, distributed denial of service attacks on network servers, and as a spam platform.Trojans do not reproduce by infecting other files nor do they self-replicate. Trojans must spread through user interaction such as opening an e-mail attachment or downloading and running a file from the Internet.
Bacteria, or rabbit programs, make copies of themselves to overwhelm a computer system’s resources. Bacteria do not explicitly damage any files. Their sole purpose is to replicate themselves. A typical bacteria program may do nothing more than execute two copies of itself simultaneously on multiprogramming systems, or perhaps create two new files, each of which is a copy of the original source file of the bacteria program. Both of those programs then may copy themselves twice, and so on. Bacteria reproduce exponentially, eventually taking up all the processor capacity, memory, or disk space, denying the user access to those resources.
A dropper is a program that is not a virus, nor is it infected with a virus, but when run it installs a virus into memory, on to the disk, or into a file. Droppers have been written sometimes as a convenient carrier for a virus, and sometimes as an act of sabotage.It is designed to “install” some sort of malware (virus, backdoor, etc.) to a target system. The malware code can be contained within the dropper (single-stage) in such a way as to avoid detection by virus scanners or the dropper may download the malware to the target machine once activated (two stage).
Blended threats combine the characteristics of viruses, worms, Trojan Horses, and malicious code with server and Internet vulnerabilities to initiate, transmit, and spread an attack. By using multiple methods and techniques, blended threats can rapidly spread and cause widespread damage. It posses all the characteristics of a perfect migraine.
Bot is derived from the word “robot” and is an automated process that interacts with other network services. Bots often automate tasks and provide information or services that would otherwise be conducted by a human being. A typical use of bots is to gather information (such as web crawlers), or interact automatically with instant messaging (IM), Internet Relay Chat (IRC), or other web interfaces. They may also be used to interact dynamically with websites.
In general we can say that these viruses and stuffs will only infect our system if we allow them to. Whenever installing third party software or some files we must go through its license and agreement thoroughly.Dont open suspicious emails or attachments from any sources. Dont click on links in emails requesting your personal details. Always sign out when you’ve finished reading your email. If possible treat all emails as suspicious even an email from a friend may be infected.Update all your software, browsers and OS.Install a firewall hardware or software to stop certain computers or networks from accessing your system without your permission.
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