12 Replies Latest reply: May 22, 2013 3:26 PM by thomas_r.
Intructions Level 1 (0 points)

I have heard people say that you do and other people say that you don't. Which one is it?


  • mende1 Level 10 (92,201 points)

    OS X has got its own security systems, and antiviruses just make the computer slow, so you don't need any antivirus. See > http://www.thesafemac.com/mmg


    Anyway, if you have to install an antivirus, we recommend ClamXav and Sophos, but not different antiviruses

  • Eric Ross Level 6 (11,665 points)
  • Intructions Level 1 (0 points)

    How do you know if you need it?

  • mende1 Level 10 (92,201 points)

    For example, if you connect USB drives to your Mac that you are going to use with a PC. In this case, I recommend you to have an antivirus just to check the USB drive and the files you put into it, because your Mac isn't affected by viruses, but you can transfer them to other PCs

  • MrHoffman Level 6 (14,832 points)

    Entirely your call....


    Recent malware for various platforms has been based on Adobe Flash and on Oracle Java.  Consider avoiding those tools.


    Consider how you use your computer.... If you tend to download stuff from sites other than the Mac App Store (and particularly if you're prone to downloading and installing stuff that you didn't go looking for), if you're loading or otherwise using torrents "incautiously", if you're loading software from sites other than the developer's own (whether torrents or any of the various "download" sites), if you automatically type your administrative password when you're prompted for it by something, if you click on links in random mail messages believing that message is really from LinkedIn or Facebook or your cellular provider or your bank or your best friend, if you're running with Adobe Flash installed and with the Oracle Java JVM WebStart plug-in enabled in your browser(s), and if you're prone to picking weak passwords, then you might want to acquire and load some anti-malware software.


    Having regular backups can also a key part of recovering from a malware problem; rolling back to before the problem and then "closing the hole" is a common recovery technique.


    But realize that anti-malware tools are far from a panacea, as they're inherently prone to missing new and changed and "polymorphic" malware, and any of the tools can (unintentionally) render your Mac unstable, uncooperative and otherwise flaky.  In how they insert themselves into the operating system, anti-malware tools can act like the malware they're defending against, after all.


    If you don't do that sort of thing, and if you treat that administrative password as the "key" to your calendar, your address book, your email, your keychain login passwords to Facebook, LinkedIn and whereever, and granting access to the rest of your environment — that's what that administrative password is, after all — and if you keep good backups, then the built-in Xprotect tool does fairly well even with the recent malware.


    If you're swapping storage with Windows or presenting file shares to a network, then you can use ClamAV as that can scan files and quarantine malware for various platforms including Windows and OS X.  ClamAV is installed with OS X Server, and there are ports of ClamAV available for OS X client via Fink, Homebrew and MacPorts.  There's also ClamXAV around — here is the ClamXAV Mac App Store link — that other thread has an indirect pointer.


    I generally run with the built-in Xprotect, with Java off or not installed, and with Flash deinstalled, and don't run nor seed torrents, and no add-on anti-malware tools.  The servers I run do use ClamAV, as they tend to have file shares.


    This question gets asked, so have a look around the forums for some previous discussions, opinions and options.


    There are trade-offs.  You know how you use your Mac.  Your call.

  • Linc Davis Level 10 (192,629 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.

    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 (see below.)
    • 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 another 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 actually been tested by Apple (unless it comes from the Mac App Store), 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. For most practical purposes, applications recognized by Gatekeeper as signed can be considered safe.
    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 evade Apple's controls.         
    4. When you install the Apple-supplied Java runtime (but not the Oracle runtime), yet another layer of protection is added: a "Malware Removal Tool" (MRT). MRT runs automatically in the background when you log in. It seems to check for, and potentially remove, malware that may have been installed via a Java exploit. Like XProtect, MRT is presumably effective against known attacks, but not against unknown attacks. There is no user interface to MRT.
    5. Beyond XProtect, Gatekeeper, and MRT, there’s no benefit, in most cases, from any other automated protection against malware. The first and best line of defense is always your own intelligence. 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. How do you know whether a source 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 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.
    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, Java on the Web is 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 inessential 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 it — not JavaScript — in your browsers. In Safari, this is done by unchecking the box marked Enable Java in the Security tab of the preferences dialog.
    Regardless of version, experience has shown that Java on the Web can't be trusted. If you must use a Java applet for a specific task, enable Java only when needed for the task and disable it immediately when done. Close all other browser windows and tabs, and don't visit any other sites while Java is active. Never enable Java on a public web page that carries third-party advertising. Use it, when necessary, 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:
    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 anti-virus software, in my opinion, is in its effect on human behavior. It does little or nothing to protect people from emerging threats, but they get a false sense of security from it, and then they may behave in ways 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.
  • Intructions Level 1 (0 points)

    so i installed mountain lion and it is really slow. haven't done any maintence for 3 years so what do i need to do to for maintence?

  • thomas_r. Level 7 (30,727 points)

    what do i need to do to for maintence?


    That's really a separate topic, and in the future would be better addressed on a new topic with a more appropriate title to get the most eyes looking at it. However, to answer the question, you don't really need to do anything as far as maintenance is concerned. See The myth of the dirty Mac.


    As to the reasons for your system to be slow, we can't do more than guess without more details. Try my Mac Performance Guide as a starting point.

  • Intructions Level 1 (0 points)

    personaly i hate your articles! they are so biased! but some good things in there anyway so i guess they were ok articles!

  • g_wolfman Level 4 (1,120 points)

    Bias: a particular tendency or inclination, especially one that prevents unprejudcied consideration of a question; prejudice.


    How exactly are Thomas' articles biased?  I personally don't always agree with him...but that's not the same thing.  To paraphrase a certain spanish duelist - I don't think that word means what you think it means.

  • Intructions Level 1 (0 points)

    Sorry poor choice of words!

  • thomas_r. Level 7 (30,727 points)

    personaly i hate your articles! they are so biased! but some good things in there anyway so i guess they were ok articles!


    I'm not sure how to respond to that. It would be far better if you could be clear about what exactly you don't like about them. You claim they're biased, but I'm not sure I understand that criticism. I try very hard to avoid bias. I'm also not quite sure how you could hate them but think they're okay...?


    If you'd like to have a constructive conversation about this, I would be glad to talk to you about it. Feel free to e-mail me privately.