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Free Antivrus for Mountain Lion.

630 Views 16 Replies Latest reply: Mar 14, 2013 7:21 AM by brbrown RSS
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brbrown Level 1 Level 1 (0 points)
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Mar 13, 2013 11:53 AM

Can anyone please direct me to a free antivirus programme for Mountain Lion? I have tried searching AVG to no avail.

iMac, OS X Mountain Lion (10.8)
  • Imp68 Level 4 Level 4 (2,135 points)
  • Linc Davis Level 10 Level 10 (107,955 points)
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    Mar 13, 2013 2:27 PM (in response to brbrown)

    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 up to three layers of built-in protection specifically against malware, not counting features such as sandboxing and address space layout randomization that may also apply to 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 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), a third layer of protection is added: a "Malware Removal Tool" (MRT). MRT runs automatically in the background when you update Java. It checks for, and removes, malware that may have evaded the other protections via a Java exploit (see below.) 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. 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 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 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 security 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.

  • petermac87 Level 5 Level 5 (4,065 points)
    Currently Being Moderated
    Mar 14, 2013 3:15 AM (in response to brbrown)

    brbrown wrote:


    Thank you both for your very helpful and detailed replies. As you realise, I am new to Mac and was very conversant with Windows and protection methods.

    Coincidentally, whilst waiting for your replies, I was expecting to receive an email from a friend with some information and clicked on the link given only to find it was not what I expected. When I rang my friend, I was told she had been hacked so I guess I have also. At the moment I cannot see anything wrong so my Mac may not be infected but as you say, I could pass on the hack to Window users.

    I tried to do a system restore only to find I needed an external drive to form a first backup to enable a restore if need be. Then I thought I would download your suggested software in the hope that it would clear the offending hack but the download page strongly recommended backing up my system before I download. I do not yet have an external hard drive to back up with.


    Have you any suggestions as to how I can find and clear the hack? Would the software you mention help? If so, would it be safe to download without a backup?


    The only AV I would ever use on a Mac if it were needed.


    Safe to download and install, although I would highly recommend you think seriously about setting yourself up with a reliable backup setup.





  • thomas_r. Level 7 Level 7 (26,980 points)
    Currently Being Moderated
    Mar 14, 2013 3:57 AM (in response to brbrown)

    Clicking a link like that does not mean that your Mac is instantly hacked.


    First question, have you installed Java on your machine, and if so, is it enabled in your web browser? If you answered yes to both, you are at risk of drive-by downloads. It's still very unlikely that the link you visited would have resulted in installing Mac malware, which is still pretty rare, but it's possible. You may want to run a scan with anti-virus software.


    Second question, have you installed Adobe Flash Player? If so, the same applies.


    Java and Flash are the two most prominent ways to get your Mac infected. Java should not be used at all at this point, and Flash should be avoided or controlled with some kind of "click-to-play" functionality.


    For more information on this, see my Mac Malware Guide. If you decide to get anti-virus software, use one of the programs it recommends.

  • Barney-15E Level 7 Level 7 (33,410 points)
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    Mar 14, 2013 4:37 AM (in response to brbrown)

    There are some web sites that use Java. From reports, a lot of Norwegian Banking websites depend on Java. However, it is very rare to find a site that needs it.


    Flash is predominately needed for web ads and some video streaming sites. As Thomas mentioned, use ClickToFlash or ClickToPlugin Safari extensions. The first just blocks Flash content from displaying automatically. If you want to see it, you click on it. The second blocks a lot of different plugins.

    You can whitelist a website so that you don't have to click on its Flash content.

    I use ClickToPlugin and you can set it to automatically substitute a website's HTML5 rendering instead of Flash, if it is available. I'm not sure about ClickToFlash.

  • thomas_r. Level 7 Level 7 (26,980 points)
    Currently Being Moderated
    Mar 14, 2013 4:40 AM (in response to brbrown)

    Very few pages these days still require Java, and given the number of times new Java vulnerabilities have been found they will only dwindle further. See:


    Java is vulnerable… Again?!


    As for Flash, it's definitely more pervasive on the web than Java, but Adobe has been doing a pretty good job of keeping that up-to-date. They respond quickly to vulnerabilities (unlike Oracle, who has still not fixed the latest Java vulnerabilities), and there are fewer vulnerabilities found. Still, Flash is also something that is wise to be cautious of. If you want to use Flash, you should use something like ClickToFlash in Safari or "click-to-play" features in other browsers to prevent Flash content from loading without your explicit permission.


    Edit: I notice Barney mentioned ClickToPlugin, which would work as well as ClickToFlash. It's important to note, though, that ClickToPlugin cannot protect against malicious Java applets. That is a common misconception, based on the fact that ClickToPlugin can block certain kinds of Java content, and I just wanted to be sure you are aware of this if you install it.

  • ~Bee Level 7 Level 7 (30,580 points)
  • WZZZ Level 6 Level 6 (11,880 points)
    Currently Being Moderated
    Mar 14, 2013 6:05 AM (in response to brbrown)

    If you have Safari 5.1.7 or above, you need clicktoplugin. Go to Preferences>Extensions>Get Extensions in Safari and find it there.

  • thomas_r. Level 7 Level 7 (26,980 points)
    Currently Being Moderated
    Mar 14, 2013 6:42 AM (in response to brbrown)

    Links are in the guide I referred you to... specifically, on this page:


    How can I protect myself?

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