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Linux vs. Windows Viruses
SecurityFocus ^ | 2 October 2003 | Scott Granneman

Posted on 10/06/2003 8:31:20 AM PDT by ShadowAce

To mess up a Linux box, you need to work at it; to mess up your Windows box, you just need to work on it.

We've all heard it many times when a new Microsoft virus comes out. In fact, I've heard it a couple of times this week already. Someone on a mailing list or discussion forum complains about the latest in a long line of Microsoft email viruses or worms and recommends others consider Mac OS X or Linux as a somewhat safer computing platform. In response, another person named, oh, let's call him "Bill," says, basically, "How ridiculous! The only reason Microsoft software is the target of so many viruses is because it is so widely used! Why, if Linux or Mac OS X was as popular as Windows, there would be just as many viruses written for those platforms!"

Of course, it's not just "regular folks" on mailing lists who share this opinion. Businesspeople have expressed similar attitudes ... including ones who work for anti-virus companies. Jack Clarke, European product manager at McAfee, said, "So we will be seeing more Linux viruses as the OS becomes more common and popular."

Mr. Clarke is wrong.

Sure, there are Linux viruses. But let's compare the numbers. According to Dr. Nic Peeling and Dr Julian Satchell's Analysis of the Impact of Open Source Software (note: the link is to a 135 kb PDF file):

"There are about 60,000 viruses known for Windows, 40 or so for the Macintosh, about 5 for commercial Unix versions, and perhaps 40 for Linux. Most of the Windows viruses are not important, but many hundreds have caused widespread damage. Two or three of the Macintosh viruses were widespread enough to be of importance. None of the Unix or Linux viruses became widespread - most were confined to the laboratory."

Microsoft's email software is able to infect a user's computer when they do something as innocuous as read an email!


So there are far fewer viruses for Mac OS X and Linux. It's true that those two operating systems do not have monopoly numbers, though in some industries they have substantial numbers of users. But even if Linux becomes the dominant desktop computing platform, and Mac OS X continues its growth in businesses and homes, these Unix-based OS's will never experience all of the problems we're seeing now with email-borne viruses and worms in the Microsoft world. Why?

Why are Linux and Mac OS X safer?

First, look at the two factors that cause email viruses and worms to propagate: social engineering, and poorly designed software. Social engineering is the art of conning someone into doing something they shouldn't do, or revealing something that should be kept secret. Virus writers use social engineering to convince people to do stupid things, like open attachments that carry viruses and worms. Poorly designed software makes it easier for social engineering to take place, but such software can also subvert the efforts of a knowledgable, security-minded individual or organization. Together, the two factors can turn a single virus incident into a widespread disaster.

Let's look further at social engineering. Windows software is either executable or not, depending on the file extension. So if a file ends with ".exe" or ".scr", it can be run as a program (yes, of course, if you change a text file's extension from ".txt" to ".exe", nothing will happen, because it's not magically an executable; I'm talking about real executable programs). It's easy to run executables in the Windows world, and users who get an email with a subject line like "Check out this wicked screensaver!" and an attachment, too often click on it without thinking first, and bang! we're off to the races and a new worm has taken over their systems.

Even worse, Microsoft's email software is able to infect a user's computer when they do something as innocuous as read an email! Don't believe me? Take a look at Microsoft Security Bulletins MS99-032, MS00-043, MS01-015, MS01-020, MS02-068, or MS03-023, for instance. Notice that's at least one for the last five years. And though Microsoft's latest versions of Outlook block most executable attachments by default, it's still possible to override those protections.



This sort of social engineering, so easy to accomplish in Windows, requires far more steps and far greater effort on the part of the Linux user. Instead of just reading an email (... just reading an email?!?), a Linux user would have to read the email, save the attachment, give the attachment executable permissions, and then run the executable. Even as less sophisticated users begin to migrate to Linux, they may not understand exactly why they can't just execute attachments, but they will still have to go through the steps. As Martha Stewart would say, this is a good thing. Further, due to the strong community around Linux, new users will receive education and encouragement in areas such as email security that are currently lacking in the Windows world, which should help to alleviate any concerns on the part of newbies.

Further, due to the strong separation between normal users and the privileged root user, our Linux user would have to be running as root to really do any damage to the system. He could damage his /home directory, but that's about it. So the above steps now become the following: read, save, become root, give executable permissions, run. The more steps, the less likely a virus infection becomes, and certainly the less likely a catastrophically spreading virus becomes. And since Linux users are taught from the get-go to never run as root, and since Mac OS X doesn't even allow users to use the root account unless they first enable the option, it's obvious the likelihood of email-driven viruses and worms lessens on those platforms.

Unfortunately, running as root (or Administrator) is common in the Windows world. In fact, Microsoft is still engaging in this risky behavior. Windows XP, supposed Microsoft's most secure desktop operating system, automatically makes the first named user of the system an Administrator, with the power to do anything he wants to the computer. The reasons for this decision boggle the mind. With all the lost money and productivity over the last decade caused by countless Microsoft-borne viruses and worms, you'd think the company could have changed its procedures in this area, but no.

Even if the OS has been set up correctly, with an Administrator account and a non-privileged user account, things are still not copasetic. On a Windows system, programs installed by a non-Administrative user can still add DLLs and other system files that can be run at a level of permission that damages the system itself. Even worse, the collection of files on a Windows system - the operating system, the applications, and the user data - can't be kept apart from each other. Things are intermingled to a degree that makes it unlikely that they will ever be satisfactorily sorted out in any sensibly secure fashion.

The final reason why social engineering is easier in the Windows world is also an illustration of the dangers inherent in any monoculture, whether biological or technological. In the same way that genetic diversity in a population of living creatures is desirable because it reduces the likelihood that an illness - like a virus - will utterly wipe out every animal or plant, diversity in computing environments helps to protect the users of those devices.

Linux runs on many architectures, not just Intel, and there are many versions of Linux, many packaging systems, and many shells. But most obvious to the end user, Linux mail clients and address books are far from standardized. KMail, Mozilla Mail, Evolution, pine, mutt, emacs ... the list goes on. It's simply not like the Windows world, in which Microsoft's email programs - Outlook and Outlook Express - dominate. In the Windows world, a virus writer knows how the monoculture operates, so he can target his virus, secure in the knowledge that millions of systems have the same vulnerability. A virus targeted to a specific vulnerability in Evolution, on the other hand, might affect some people, but not everyone using Linux. The growth of the Microsoft monoculture in computing is a dangerous thing for users of Microsoft products, but also for all computing users, who suffer the consequences of disasters in that environment, such as wasted network resources, dangers to national security, and lost productivity (note: the link is to a 880 kb PDF file).

Now that we've looked at the social engineering side of things, let's examine software design for reasons why Linux (and Mac OS X) is better designed than Microsoft when it comes to email security. Microsoft continually links together its software, often not for technical reasons, but instead for marketing or business development reasons (see the previous link for corroboration). For instance, Outlook Express and Outlook both use the consistently-buggy Internet Explorer to view HTML-based emails. As a result, a hole in IE affects OE. Linux email readers don't indulge in such behavior, with two exceptions: Mozilla Mail uses the Gecko engine that powers Mozilla to view HTML-based email, while KMail relies on the KHTML engine that the Konqueror browser uses. Fortunately, both Mozilla and the KDE Project have excellent records when it comes to security.

Further, the email programs themselves are designed to act in a more secure manner. The default behavior of the email program I prefer - KMail - is to not load external references in messages, such as pictures and Web bugs, and to not display HTML. When an HTML-based email shows up in my Inbox, I see only the HTML code, and a message appears at the top of the email: "This is an HTML message. For security reasons, only the raw HTML code is shown. If you trust the sender of this message then you can activate formatted HTML display for this message by clicking here." But even after I activate the HTML, certain dynamic elements that can be introduced in an HTML-based email - like Java, Javascript, plugins and even the "refresh" META tag - do not display, and cannot even be enabled in KMail.


Finally, if there is an attachment, it does not automatically run ... ever. Instead, I have to click it, and when I do, I get a dialog box offering me three options: "Save As ..." (the default), "Open With ...", and "Cancel". If I have mapped a file type to a specific program - for instance, I have associated PDFs with the PS/PDF Viewer, then "Open With ..." instead says "Open", and if I choose "Open", then the file opens in the PS/PDF Viewer. However, in either case, the dialog box always contains a warning advising the user that attachments can compromise security. This is all good, very good.

For all these reasons, even if a few individuals got infected with a virus due to extremely foolish behavior, it's unlikely the virus would spread to other machines. Unlike Sobig.F, which is the fastest spreading virus ever, a Linux-based Virus would fizzle out quickly. Windows is an inviting petri dish for viruses and worms, while Linux is a hostile environment for such nasties.

Some caveats

There is one Linux distribution that is ignoring many years of common sense, good design, and an awareness of secure operating environments in favor of a Microsoft-like deprecation of security before the nebulous term "ease of use": Lindows. By default, Lindows runs the user of the system as root (and it even encourages the user to forgo setting up a root password during installation by labeling it as "optional"!), an unbelievably shortsighted decision that results in a Linux box with the same security as a Windows 9.x machine.



If you go to the Lindows Web site, they state that it is possible to add other, non-privileged users, but nowhere in the operating system do they advocate adding these other users. Yet they claim their distribution of Linux is secure! In an effort to emulate Microsoft and make things "easy", they have compromised the security of their users, an unforgivable action. No one in the field of security, or even IT, can recommend Lindows while such a blatant disregard for security is the norm for the OS.

Yet some Linux machines definitely need anti-virus software. Samba or NFS servers, for instance, may store documents in undocumented, vulnerable Microsoft formats, such as Word and Excel, that contain and propagate viruses. Linux mail servers should run AV software in order to neutralize viruses before they show up in the mailboxes of Outlook and Outlook Express users.

Security is, as we all know, a process, not a product. So when you use Linux, you're not using a perfectly safe OS. There is no such thing. But Linux and Mac OS X establish a more secure footing than Microsoft Windows, one that makes it far harder for viruses to take hold in the first place, but if one does take hold, harder to damage the system, but if one succeeds in damaging the system, harder to spread to other machines and repeat the process. When it comes to email-borne viruses and worms, Linux may not be completely immune - after all, nothing is immune to human gullibility and stupidity - but it is much more resistant. To mess up a Linux box, you need to work at it; to mess up your Windows box, you just need to work on it. I know which one I'll trust. How about you?


TOPICS: Business/Economy; Culture/Society; Technical
KEYWORDS: apple; linux; macuser; virii; viruses; windows
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1 posted on 10/06/2003 8:31:20 AM PDT by ShadowAce
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To: rdb3; TechJunkYard; chance33_98; Calvinist_Dark_Lord; Dominic Harr; Bush2000; Nick Danger; ...
Tech Ping
2 posted on 10/06/2003 8:32:13 AM PDT by ShadowAce (Linux -- The Ultimate Windows Service Pack)
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To: All

I'M BACK!!!

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3 posted on 10/06/2003 8:33:53 AM PDT by Support Free Republic (Your support keeps Free Republic going strong!)
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To: ShadowAce
My OS can beat up your OS.
4 posted on 10/06/2003 8:35:58 AM PDT by Grit (Tolerance for all but the intolerant...and those who tolerate intolerance etc etc)
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To: Grit
LOL - I can just picture trying to get "Uncle Bubba" to read his e-mail in Linux. One of the considerations that seems to be ignored is that many of the virii that spread so far are due to user ignorance. Those users would make the same kind of mistakes on any operating system, or would be unable to use it.
5 posted on 10/06/2003 8:49:06 AM PDT by Ingtar (Understanding is a three-edged sword : your side, my side, and the truth in between ." -- Kosh)
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To: ShadowAce
It's all about numbers. No one is going to create a devastating Linux virus in order to disrupt a fraction of the people affected by Windows viruses. If you build it (the Linux user base), they (the virus writers) will come.
6 posted on 10/06/2003 8:49:26 AM PDT by Mr. Bird
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To: John Robinson; B Knotts; stainlessbanner; TechJunkYard; ShadowAce; Knitebane; AppyPappy; jae471; ...
The Penguin Ping.

Wanna be Penguified? Just holla!

Got root?

7 posted on 10/06/2003 8:50:10 AM PDT by rdb3 (2Pac could have used a decoy that night...)
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To: ShadowAce
Instead of just reading an email (... just reading an email?!?), a Linux user would have to read the email, save the attachment, give the attachment executable permissions, and then run the executable.

And therein lies the rub...

For common users, an effective OS must balance security, ease-of-use, and cost-effectiveness. These all have trade-offs against one another.

You can make a fair argument that Microsoft has not struck the right balance, because of their desktop, pre-Internet tendencies. But just layering on more security is not the answer either. Software is going to be distributed over the Internet, and many common users are never going to learn how to manipulate executable settings.

So who's going to finally strike the right balance on security vs. usability vs. cost? Linux, which is aimed at geeks for the most part? Apple, which has always had premium prices? Or Microsoft, which has billions to spend and a huge installed base to protect, and has shown itself to be successful at producing what the common user wants to buy?

Well, I know Microsoft is doing something for the long term. They are transitioning their operating system API towards "managed code" in which, for example, buffer overruns (and the vulnerabilities they present) are impossible.

Perhaps Linux and the Mac are also addressing their limitations - with usability enhancements for Linux and more cost-effective alternatives for the Mac. Great. In that case, we'll have a competitive market, and it will be good for everybody.

But just slamming Microsoft as the villian in this drama is not helpful. Every currently available OS has strengths and weaknesses, and focusing on security while ignoring usability and cost-effectiveness means you can't do a very good job of analyzing those strengths and weaknesses.

8 posted on 10/06/2003 8:54:13 AM PDT by Joe Bonforte
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To: ShadowAce
*** since Mac OS X doesn't even allow users to use the root account unless they first enable the option, it's obvious the likelihood of email-driven viruses and worms lessens on those platforms.

Unfortunately, running as root (or Administrator) is common in the Windows world. ***

Okay, computer experts, can you answer this question for me? I'm on Mac OSX, and it insists that I have an administrator. Since I own the computer and am the only user, I have to be the admin. Does that mean that I am "using as root"? And, if I am, what can I do about it?

Also, when it comes to Windows Media User, I am sometimes automatically plugged into it by the site and can view progams with no problem. But, if I SIGN UP for it on other sites, I am constantly refused admission because they claim I am NOT the administrator even though I am. What's up with that?

Sitting back and hoping I can understand your answers.
9 posted on 10/06/2003 8:58:19 AM PDT by kitkat
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To: ShadowAce
Guess I'll get this in first, before the MS drones show up:

How dare you impugn the honor and integrity of Might Microsoft with mere logic! You're just jealous because Windows sells so much! And it sells because it's a superior product.

10 posted on 10/06/2003 8:59:28 AM PDT by irv
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To: ShadowAce
oohhh, another Win/*nix thread. Maybe this'll be the one that finally solves it!!! Maybe there will be substantive discussion instead of mere gnashing of teeth.

[sigh] yeah, right... :-)
11 posted on 10/06/2003 9:00:34 AM PDT by Ramius (--> comfortably numb <--)
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To: irv
Guess I'll get this in first, before the MS drones show up:

Too late.

12 posted on 10/06/2003 9:01:15 AM PDT by irv
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To: ShadowAce
This message includes a lot of truth, but also a lot of artial truths.
Most people running Linux have some knowledge about security and computers. They don't login as root unless they need to do so; they don't usually surf the web as root either. On the other hand, most Windows users (and the speaders of 90+% of the virii) are neophytes.
Disturbingly, in my own experiments back in 1999, I discovered that about 85-95% of people hitting my webserver with Windows NT 4.0 were surfing the web as administrator. I wrote a little program that would exploit this fact to crack the administrator passwords and post the first few characters of the password online as a proof of concept.
It is possible to write Linux virii and worms or even MacOS virii that can do a whole lot of damage to a system. (Of course, you could just leave the Mac on and let the OS act as a virus, but that is an entirely different matter--"Eject the disk Macintosh HD" and "Please re-insert the disk Macintosh HD".) Most malicious work is done by hacker-wannabes. These are often 13-year-old script-kiddies that download a tutorial, virus toolkit, or worm base code and click a button to unleash it on the world. Fortunately for the MacOS and Linux world, these don't really exist to exploit the holes in either OS or its software. They aren't big enough targets.
Besides, if you want a newbie to screw over his or her linux distrib, why not send a shell script with 'rm -r .' in it? If you want to screw a Mac user over, give them a simple AppleScript that wipes the HDD or maybe just all the extensions . . . The coding time involved takes about, oh, a total of <5 mins--very simple/trival code.
In terms of overall computer knowledge among OS users: Linux >> Windows >> MacOS.
13 posted on 10/06/2003 9:03:06 AM PDT by yevgenie
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To: Ramius
unix is dying.
14 posted on 10/06/2003 9:04:14 AM PDT by epluribus_2
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To: Ramius
Great! Just what we needed as a break from the grueling Arnie/McClintock/Davis/Busty wars!!!
15 posted on 10/06/2003 9:06:12 AM PDT by chilepepper (The map is not the territory -- Alfred Korzybski)
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To: irv
And it sells because it's a superior product.

No, no, no, it's the other way around -- it's a superior product because it sells so much!

MS is the 'Brittney Spears' or 'McDonalds' of software, selling low-quality mass-market goods. The only problem is the folks who use MS in their real work. It's the same thing as if a professional caterer were to serve McDonalds food at a wedding. The IT world is just a brand-new market where consumers are largely completely ignorant. And there's no shortage of IT folks out there willing to sell them McDonalds, just to make a buck.

I always imagine the people around Brittney telling her the same things you hear from the MS-only folks. "Don't listen to the critics, Britt, you *do* have talent! You sell the most albums, that means you're the best singer in the world!"

16 posted on 10/06/2003 9:08:54 AM PDT by Dominic Harr
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To: epluribus_2
unix is dying.

No I'm not, doing just fine, thank you very much.

17 posted on 10/06/2003 9:09:01 AM PDT by Michael Barnes
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To: Joe Bonforte
But just slamming Microsoft as the villian in this drama is not helpful. Every currently available OS has strengths and weaknesses, and focusing on security while ignoring usability and cost-effectiveness means you can't do a very good job of analyzing those strengths and weaknesses.

Right on, brother!

18 posted on 10/06/2003 9:14:43 AM PDT by DallasMike
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To: ShadowAce
Right now, I'm probably running one of the most secure systems going.

I'm running Knoppix 3.2 (Linux) from a CD with no hard drives mounted.

If I get a virus, I just reboot and it's gone.
19 posted on 10/06/2003 9:18:42 AM PDT by FLAMING DEATH (Why do I carry a .45? Because they don't make a .46!)
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To: ShadowAce
When Linux moves beyond its "geekiness" and appeal to end-users, then maybe it will see more users. Myself, I'm know a bit more than the average user yet not as much as the "geek". I don't want to be bothered with Linux because, first of all, I have way too much software that wouldn't run on it. Secondly, I LOVE desktop themes. Call me silly but I don't like looking at the same desktop all the time and Windows allows me to do that, to change my desktop. Thirdly, all I have to do is point and click, not try to memorize a bunch of "geek speak" that Linux incorporates. Now, maybe if I saw one of these Linux machine with all the "eye-candy" I want and security, then maybe. But, bashing Microsoft only appeals to the Linux-bots out there who hate MS anyway. Doesn't mean anything to the average end-user who just wants to check their e-mail, play a few games and keep track of stock quotes.
20 posted on 10/06/2003 9:20:30 AM PDT by Sister_T (Yeah, DemocRATS are racists, too!)
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