7 Replies Latest reply: May 5, 2013 10:52 AM by bettyfromst. george
wcrowder Level 1 Level 1 (0 points)

I used windows, then linux from 2005- now. I have a macbook air. should i be using antivirus?


MacBook Air (11-INCH, MID 2011), OS X Mountain Lion (10.8.2)
  • 1. Re: antivirus
    Niel Level 10 Level 10 (241,935 points)

    Mac OS X's built-in defenses and common sense are enough unless you're running Windows on the computer; ClamXav and/or Sophos may be useful but aren't needed.

     

    (82180)

  • 2. Re: antivirus
    wcrowder Level 1 Level 1 (0 points)

    Niel,

     

    Thanks for the response. So why does norton, mcaffee, etc make products? Am I really safe without it? I felt very safe on linux I am hessitant on Mac. I suppose Apple tends to be more active in software updates than MS is - is that why its not needed?

  • 3. Re: antivirus
    Linc Davis Level 10 Level 10 (117,870 points)

    1. This comment applies to malicious software ("malware") that's installed unwittingly by the victim of a network attack. It does not apply to software, such as keystroke loggers, that may be installed deliberately by an intruder who has hands-on access to the victim's computer. That threat is in a different category, and there's no easy way to defend against it. If you have reason to suspect that you're the target of such an attack, you need expert help.
      
    OS X now implements three layers of built-in protection specifically against malware, not counting runtime protections such as execute disable, sandboxing, system library randomization, and address space layout randomization that may also guard against other kinds of exploits.

    2. All versions of OS X since 10.6.7 have been able to detect known Mac malware in downloaded files, and to block insecure web plugins. This feature is transparent to the user, but internally Apple calls it "XProtect." The malware recognition database is automatically checked for updates once a day; however, you shouldn't rely on it, because the attackers are always at least a day ahead of the defenders.
       
    The following caveats apply to XProtect:
    • It can be bypassed by some third-party networking software, such as BitTorrent clients and Java applets.
    • It only applies to software downloaded from the network. Software installed from a CD or other media is not checked.
    3. Starting with OS X 10.7.5, there has been a second layer of built-in malware protection, designated "Gatekeeper" by Apple. By default, applications and Installer packages downloaded from the network will only run if they're digitally signed by a developer with a certificate issued by Apple. Software certified in this way hasn't necessarily been tested by Apple, but you can be reasonably sure that it hasn't been modified by anyone other than the developer. His identity is known to Apple, so he could be held legally responsible if he distributed malware. That may not mean much if the developer lives in a country with a weak legal system (see below.)
       
    Gatekeeper doesn't depend on a database of known malware. It has, however, the same limitations as XProtect, and in addition the following:
    • It can easily be disabled or overridden by the user.
    • A malware attacker could get control of a code-signing certificate under false pretenses, or could find some other way to bypass Apple's oversight, or the oversight could fail in a particular case due to human error.
    For most purposes, applications recognized by Gatekeeper as signed, including App Store products, can be considered safe. Note, however, that at least one trojan for iOS (not for OS X) was briefly distributed by a developer in Russia through the iTunes App Store. That store is under the same oversight by Apple as the Mac App Store, so the protection shouldn't be considered absolute. App Store products may prompt for access to private data, such as your contacts. Think before granting that access. OS X security is based on user input. Never click anything reflexively.
           
    4. Starting with OS X 10.8.3, a third layer of protection has been added: a "Malware Removal Tool" (MRT). MRT runs automatically in the background when you update the OS. It checks for, and removes, malware that may have evaded the other protections via a Java exploit (see below.) MRT also runs when you install or update the Apple-supplied Java runtime (but not the Oracle runtime.) Like XProtect, MRT is presumably effective against known attacks, but maybe not against unknown attacks. It notifies you if it finds malware, but otherwise there's no user interface to MRT.
     
    5. Beyond XProtect, Gatekeeper, and MRT, there’s no evidence of any benefit from other automated protection against malware. The first and best line of defense is always your own intelligence. With the possible exception of Java exploits, all known malware circulating on the Internet that affects a fully-updated installation of OS X 10.6 or later takes the form of so-called "trojan horses," which can only have an effect if the victim is duped into running them. The threat therefore amounts to a battle of wits between you and the malware attacker. If you're smarter than he thinks you are, you'll win.
        
    That means, in practice, that you never use software that comes from an untrustworthy source, or that does something inherently untrustworthy. How do you know what is trustworthy?
    • Any website that prompts you to install a “codec,” “plug-in,” "player," "extractor," or “certificate” that comes from that same site, or an unknown one, is untrustworthy.
    • A web operator who tells you that you have a “virus,” or that anything else is wrong with your computer, or that you have won a prize in a contest you never entered, is trying to commit a crime with you as the victim. (Some reputable websites did legitimately warn visitors who were infected with the "DNSChanger" malware. That exception to this rule no longer applies.)
    • Pirated copies or "cracks" of commercial software, no matter where they come from, are unsafe.
    • Software of any kind downloaded from a BitTorrent or from a Usenet binary newsgroup is unsafe.
    • Software that purports to help you do something that's illegal or that infringes copyright, such as saving streamed audio or video for reuse without permission, is unsafe. All YouTube "downloaders" are in this category, though not all are necessarily harmful.
    • Software with a corporate brand, such as Adobe Flash Player, must be downloaded directly from the developer’s website. If it comes from any other source, it's unsafe.
    • Even signed applications should not be trusted if they do something unexpected, such as asking for permission to access your contacts or your location for no apparent reason.
    6. Java on the Web (not to be confused with JavaScript, to which it's not related, despite the similarity of the names) is a weak point in the security of any system. Java is, among other things, a platform for running complex applications in a web page, on the client. That was always a bad idea, and Java's developers have proven themselves incapable of implementing it without also creating a portal for malware to enter. Past Java exploits are the closest thing there has ever been to a Windows-style virus affecting OS X. Merely loading a page with malicious Java content could be harmful.
      
    Fortunately, client-side Java on the Web is obsolete and mostly extinct. Only a few outmoded sites still use it. Try to hasten the process of extinction by avoiding those sites, if you have a choice. Forget about playing games or other non-essential uses of Java.
       
    Java is not included in OS X 10.7 and later. Discrete Java installers are distributed by Apple and by Oracle (the developer of Java.) Don't use either one unless you need it. Most people don't. If Java is installed, disable itnot JavaScript — in your browsers.
       
    Regardless of version, experience has shown that Java on the Web can't be trusted. If you must use a Java applet for a task on a specific site, enable Java only for that site in Safari. Never enable Java for a public website that carries third-party advertising. Use it only on well-known, login-protected, secure websites without ads. In Safari 6 or later, you'll see a lock icon in the address bar with the abbreviation "https" when visiting a secure site.

    Follow the above guidelines, and you’ll be as safe from malware as you can practically be. The rest of this comment concerns what you should not do to protect yourself from malware.

    7. Never install any commercial "anti-virus" or "Internet security" products for the Mac, as they all do more harm than good, if they do any good at all. If you need to be able to detect Windows malware in your files, use the free software  ClamXav — nothing else.
      
    Why shouldn't you use commercial "anti-virus" products?
    • Their design is predicated on the nonexistent threat that malware may be injected at any time, anywhere in the file system. Malware is downloaded from the network; it doesn't materialize from nowhere.
    • In order to meet that nonexistent threat, the software modifies or duplicates low-level functions of the operating system, which is a waste of resources and a common cause of instability, bugs, and poor performance.
    • By modifying the operating system, the software itself may create weaknesses that could be exploited by malware attackers.
    8. ClamXav doesn't have these drawbacks. That doesn't mean it's entirely safe. It may report email messages that have "phishing" links in the body, or Windows malware in attachments, as infected files, and offer to delete or move them. Doing so will corrupt the Mail database. The messages should be deleted from within the Mail application.
        
    ClamXav is not needed, and should not be relied upon, for protection against OS X malware. It's useful only for detecting Windows malware. Windows malware can't harm you directly (unless, of course, you use Windows.) Just don't pass it on to anyone else.
        
    A Windows malware attachment in email is usually easy to recognize. The file name will often be targeted at people who aren't very bright; for example:
      
    ♥♥♥♥♥♥♥♥♥♥♥♥♥♥!!!!!!!H0TBABEZ4U!!!!!!!.AVI♥♥♥♥♥♥♥♥♥♥♥♥♥♥.exe
       
    ClamXav may be able to tell you which particular virus or trojan it is, but do you care? In practice, there's seldom a reason to use ClamXav unless a network administrator requires you to run an anti-virus application.
        
    9. The greatest harm done by security software, in my opinion, is in its effect on human behavior. It does little or nothing to protect people from emerging threats, but if they get a false sense of security from it, they may feel free to do things that expose them to higher risk. Nothing can lessen the need for safe computing practices.
      
    10. It seems to be a common belief that the built-in Application Firewall acts as a barrier to infection, or prevents malware from functioning. It does neither. It blocks inbound connections to certain network services you're running, such as file sharing. It's disabled by default and you should leave it that way if you're behind a router on a private home or office network. Activate it only when you're on an untrusted network, for instance a public Wi-Fi hotspot, where you don't want to provide services. Disable any services you don't use in the Sharing preference pane. All are disabled by default.

  • 4. Re: antivirus
    MadMacs0 Level 4 Level 4 (3,725 points)

    wcrowder wrote:

     

    So why does norton, mcaffee, etc make products?

    I suppose the long-time A-V developers have a large enough installed base to make it worthwhile to continue. Most of the new ones have only recently branched off from the Windows community to try and take advantage of the publicity a year or so ago when Flashback reportedly infected 600,000 OS X users. It remains to be seen whether sales will support their continued presence in the market or not. Almost all rely on hype and advertisement to scare users into buying their products with promises to guard against tomorrows threat. I'm still waiting for the first of them to prove they were able to stop even one of the so called "zero-day" infections from occurring. All the ones I have checked on were not able to get protection out for one to three days after discovery.

    I felt very safe on linux I am hessitant on Mac.

    I'm not sure why that is since with OS X they have much in common. Most of the vulnerabilities have been due to third party problems. Oracle's Java, Adobe's Flash, Microsoft Word and now IBM Notes all keep poping up in the news with a variety of un-patched vulnerabilities being exploited. Updates to OS X security involve far fewer updates by comparison.

    I suppose Apple tends to be more active in software updates than MS is - is that why its not needed?

    I'd say it's more the built-in functions of the Quarantine, XProtect and GateKeeper capabilities which both remind a user of possible dangers represented by newly installed files and can prevent the execution of un-trusted processes, if the user chooses to adopt this approach. I haven't experienced the MS software update experience for a few years now, but when I was there were plenty of security updates on a frequent basis and a lot of them covered some very old issues.  The XProtect system is capable of pushing updates out every 24 hours at this time and it's been exercised a couple of times when the malware developers were able to update things on their end in a rapid manner. I don't know whether MS has that capability with their Security Essentials software or not, but I would hope so.

  • 5. Re: antivirus
    thomas_r. Level 7 Level 7 (27,925 points)

    So why does norton, mcaffee, etc make products? Am I really safe without it?

     

    They make products because there is malware out there, and that means that there's a market for their products.

     

    You're definitely safer with anti-virus software installed, but how much safer is a good question. If you take certain precautions, you're pretty safe already, even with no anti-virus software installed at all. So the gains would be very marginal, and you would trade a certain amount of performance and stability to get them (depending on what anti-virus software you use).

     

    See my Mac Malware Guide for more information about how to protect yourself and what role anti-virus plays. Be aware that many viewpoints in forums like this one can be highly biased against anti-virus software. There are some good reasons for that, but those reasons are generalities that are often treated as absolutes.

  • 6. Re: antivirus
    Linc Davis Level 10 Level 10 (117,870 points)

    You should listen to Thomas! His opinions are balanced, colorful, many-sided, and unbiased. Also, his arrogance knows some bounds. My opinions are unbalanced, black-and-white, one-sided, and biased, and my arrogance knows no bounds.

  • 7. Re: antivirus
    bettyfromst. george Level 1 Level 1 (0 points)

    I like!