Linux is not completely shielded from virus infections; Learn about the different types of threat in Linux environment and the damage they may cause.

In the previous article, we discussed how virus have a hard time in Linux OS due to its permission system. In this article, we will see the different malware available for Linux and how they affect your system and conclude our two-part article on Virus & Anti-virus on Linux.

Viruses And Trojan Horses

Although there are only a few Linux viruses available, it is always best to use free antivirus scanners (like clam antivirus) to scan the software programs you download from unknown sources. Because if the software is infected and was run with root permission, it will infect the whole system and cause enormous damage.

Basically, the false sense of security in the user’s mind is what allows most Linux viruses to infect your system. There are some Linux distributions that allow users to login as root by default (Lindows) and falsely advertise that they are secure. But the truth is, any Linux OS that allows you to login as root by default is not securer than a Windows 9x operating systems.

Ignorance Is Bliss

The lack of knowledge that is seen in first time Linux users makes their system more protected than most Linux users, and they don’t know how to run a program or login as root by default. These types of users usually download software’s only from Linux repositories configured by that particular distro team.

For more accustomed users who use root login and download the software from many sources must be aware, that they must try to limit the habit of running unknown programs as root and if they have to, then use a free antivirus software for Linux and scan those executable’s firs before running.

Remember, as long as you don’t run applications as root and don’t install software’s from websites you don’t know or trust, a Linux OS is much safer than a Windows system with an antivirus.

Worms And Targeted Attacks

The classical threat to Unix-like systems is vulnerabilities in network daemons, such as ssh and WWW servers. These can be used by worms or for attacks against specific targets. As servers are patched quickly when a vulnerability is found, there have been only a few widespread worms of this kind. As specific targets can be attacked through a vulnerability that is not publicly known, there is no guarantee that a certain installation is secure. Also, servers without such vulnerabilities can be successfully attacked through weak passwords.

WWW Scripts

Linux servers may also be used by malware without any attack against the system itself, where e.g. WWW content and scripts are insufficiently restricted or checked and used by malware to attack visitors. Typically, a CGI script (meant for leaving comments) mistakenly allows inclusion of code exploiting vulnerabilities in the browser.

Buffer Overruns

Older Linux distributions were relatively sensitive to buffer overrun attacks: if the program did not care about the size of the buffer itself, the kernel provided only limited protection, allowing an attacker to execute arbitrary code under the rights of the vulnerable application under attack. Programs that gain root access even when launched by a non-root user (via the setuid bit) were particularly attractive to attack. However, as of 2009, most of the kernels include address space randomization, enhanced memory protection and other extensions making such attacks much more difficult to arrange.

Cross-Platform Viruses

A new area of concern identified in 2007 is that of cross-platform viruses, driven by the popularity of cross-platform applications. This was brought to the forefront of malware awareness by the distribution of an Openoffice.org virus called Bad Bunny.

Social Engineering

Linux is as vulnerable to malware that tricks the user into installing it through social engineering as other operating systems. In December 2009, a malicious waterfall screen-saver was discovered that contained a script that used the infected Linux PC in denial-of-service attacks.

Conclusion

As you can see, most of the malware discussed above need users’ permission or mistakes to take over a Linux System. And to give you an answer about is Linux is secure, yes most Linux distro’s (that don’t allow you to login as root)are more secure than Windows with basic antivirus software, but also remember, being secure doesn’t mean bulletproof. So if you’re one of these people feeling secure, think about this next time you go online. There is no bigger security hole than the one between chair and computer. Always be careful on the internet, don’t click on those links marked as dangerous(I know it sounds obvious), watch out for pop-ups and try to avoid running programs as root unless it is absolutely necessary.

Virus & Antivirus On Linux – Part 1