How Windows pc and Mac systems get infected

Why Windows malware is not posing a threat to Linux system

In this post I will make an attempt to create a synopsis of usual ways malware makes its way into Windows or Mac system. I am referring specifically to Win/Mac because the vast majority of viruses and other malware is created for these two aforementioned Operating Systems, MS Windows being particular favourite of malware writers due to its large share of OS market (that is, if we are not talking mobile phones at this point).
Malware that has been created for Windows pc, is designed for Registry based OS, and neither Linux or Unix is one, therefore, cannot become affected by it (that is one of the few reasons why I absolutely love Linux). Even though malware can affect only OS it has been designed for, there are couple of things often shared by all three most popular computer Operating Systems (as well as those found in majority of mobile smartphones): Adobe Flash and Sun Java. (In case of Linux the use of Adobe product is less common though.) Even though HTML5+DOM coding in website development is expected to eventually make the use of Flash obsolete, currently that is not the case.

Top weaknesses that can cause infection

1. Unpatched security holes.

Operating system, software and its components are always a subject to exploitation because nothing is ever 100% perfect. If latest updates are not installed, the coding and design vulnerabilities in software applications and operating system are posing a risk of being abused by malware writers. Internet browsers, Adobe products, Sun Java, Windows Media Player, Apple Quicktime all have to be updated on regular basis.
Adobe products. Adobe Reader is usually installed with Speed launcher. This feature is loaded during Windows start-up thus prolonging the OS loading and storing the associated .exe file in Applications' folder where it may simply be another useless file which may be exploited during malware attack on the system. By reading this short article you can decide whether you really need this feature. More on Adobe Acrobat Reader related security issues here.
Adobe Flash is another subject to exploitation if not kept updated. Hackers are known to exploit Flash vulnerabilities which can lead to malware infection. When visiting a website that hosts a HTML page which requires a Flash script, users may encounter a malicious Flash redirector, or malicious script written to exploit vulnerability in the Flash Interpreter which causes it to execute automatically in order to infect the computer. Flash vulnerabilities are directly related to Web application and casual online gaming security. More extensive overview on this subject can be found here.

Java, if not kept updated, is the most common way of infecting computer with trojans while browser is rendering a HTML code at some dodgy adult or software cracking tools' website. It must be noted that most exploited vulnerability on such an occasion is previous Java version that has not been uninstalled after the new, updated one has been downloaded and installed. You can check whether you have two Java versions in your Windows pc by going to Control Panel and opening Add/Remove Programs. If you do have two Java updates listed, it is recommended that you uninstall the older one. You can check your system's Java status here.

2. Javascript enabled for all sites.

Regardless of the Web browser you are using, a Javascript can make your system less secure if enabled to run on all sites. The safe way of using Javascript is to enable it exclusively for trusted sites. Javascript is often the cause of malicious redirects to a site with either a malicious content or an intent to boost the incoming traffic.

3. Online game servers.

Because of the design of the online game architecture, firewalls and anti-malware software sometimes can't detect intrusions. That provides an opportunity for hackers to abuse the victim's machine by using online bots and rootkit-like techniques. More info on data and computer security threats related to online gaming can be found here.

4. Torrent, P2P (Peer-to-Peer) networks, File Sharing programs.

Connection to these networks is making the system susceptible to remote attacks and probability of downloading infected, malicious files. That in turn can lead to identity thefts. Malicious worms, backdoor Trojans, IRCBots and rootkits spread across P2P file sharing networks, gaming, dodgy adult and underground sites.

5. Infected files on USB and other storage media.

An Autorun.inf file can cause much trouble. More about this threat and how to avoid it you can read here.

6. Clicking unsolicited links in e-mail and Instant Messenger chats.

For more info as to why such links are being sent and what consequences such actions can have please see my previous posts here and here.

7. Rogue antivirus / antimalware software.

This includes clicking on pop-ups or banners that claim your computer is infected. All about rogues you can read in one of my previous posts here.

8. Backing up infected files.

A logical cause of re-infection.

9. Assuming that antivirus and/or firewall are not needed, or that they are providing 100% protection.

Two extreme assumptions that both can result in computer not being protected against cyber threats. On the first occasion, it is most likely that such a computer's owner won't even get that far as to visit this website to read this article, therefore, I am going to address the second assumption by saying that even protected machines get infected. Otherwise malware writers wouldn't waste their time on doing what they do. Here is an excerpt from Ivizsecurity.com blog:

Security products like anti-virus, firewalls, IDS/IPS and VPN have become of paramount importance to provide highest degree of confidentiality, availability and Integrity (CIA) to individuals and organizations. However, it is foolish to assume that security products are free from any vulnerability (security flaws). Security Products can also be of target of attacks from the attackers.

  By assuming that Anti-virus and Firewall will do the trick of fully protecting the machine, we risk to return to the beginning of this list, e.g. unpatched security holes.

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