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elsie2 Level 1 Level 1 (0 points)

How do you know if you have malware, spyware and viruses that can steal your passwords and content without you even knowing it?  The answer I hear so often is Macs don't get viruses.  How is that possible?

  • Kurt Lang Level 8 Level 8 (35,185 points)

    A virus is a type of malware, and there are no viruses which can affect a Mac. The closest there has ever been to such a thing was a Java attack that could install software onto your Mac simply by entering a compromised web site. Since part of the definition of a virus is malware that can replicate without user intervention, that Java attack could be considered the first.


    Otherwise, it's all still foolishness, or lack of knowledge on the part of the user that gets any other type of malware on a Mac. These fall under the Trojan category. The number one way criminals are attacking Macs are illegal software downloads from torrents and other such file sharing sites. They put other software into the installer packages that wouldn't normally be there. Like keyloggers or backdoors in an illegal copy of Photoshop. When you install the illegal software, you also install whatever else is in it.


    If all of your software was legally purchased and obtained from legitimate sites, you have little to worry about. Do not believe sites that sell expensive software for ridiculously low prices. Like the Adobe CS6 Master Collection for $50 as a download. There's nothing legal about that. They get $50, your credit card number, and likely malware installed on your computer with whatever you think you legally purchased.

  • Carolyn Samit Level 10 Level 10 (96,730 points)

    If your Mac has v10.7 Lion or v10.8 Mountain Lion installed, make sure you have Gatekeeper enabled to prevent malware.


    Instructions here > OS X: About Gatekeeper


    Either ClamXav and Sophos can help prevent malicious code from being installed on your Mac.


    Excellent user tip regarding security >  Mac Malware: Apple Support Communities

  • Kurt Lang Level 8 Level 8 (35,185 points)

    Forgot to mention. Open your web browser preferences and turn Java off. Leave Javascript on. Despite the similar name, they do completely different things. It's Java that's full of security holes.


    If you run across a trusted site that requires Java to be enabled in the browser in order to use that site, turn Java on only for as long as you are using that site. Then turn it back off.

  • C F McBlob Level 4 Level 4 (2,865 points)

    elsie2 wrote:


    How do you know if you have malware, spyware and viruses that can steal your passwords and content without you even knowing it?  The answer I hear so often is Macs don't get viruses.  How is that possible?

    How do you know if you have malware? If you're running Windows on aPC, then there's a pretty good chance of it.

  • MadMacs0 Level 5 Level 5 (4,575 points)

    elsie2 wrote:


    How do you know if you have malware, spyware and viruses that can steal your passwords and content without you even knowing it?

    The only way you would have spyware on your computer is if you gave somebody physical access to it or permitted shared access over your network. All the malware known to exist that are capable of doing that use vulnerabilities that have been patched for years and have been targeted against small groups (e.g. Tibetan sympathizers). So as long as you keep your OS X and applications fully up-to-date, keep Java disabled except when you absolutely must use it and pay attention to any warnings you get, then you are protected against all currently known malware that can impact your computer.


    So why do you ask? If you are having issues then I recommend you start a new thread with a more descriptive subject and tell us what you are seeing.

  • Linc Davis Level 10 Level 10 (164,725 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.
    If you find this comment too long or too technical, read only sections 5, 6, and 10.
    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 simply ignore the consequences of distributing codesigned malware.
    • An App Store developer could find a way to bypass Apple's oversight, or the oversight could fail due to human error.
    For the reasons given above, App Store products, and other applications recognized by Gatekeeper as signed, are safer than others, but they can't be considered absolutely safe. "Sandboxed" applications may prompt for access to private data, such as your contacts, or for access to the network. Think before granting that access. OS X security is based on user input. Never click through any request for authorization without thinking.
    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. XProtect, Gatekeeper, and MRT reduce the risk of malware attack, but they're not absolute protection. 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, no matter what the source, should not be trusted if they do something unexpected, such as asking for permission to access your contacts, your location, or the Internet for no obvious 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. Any database of known threats is always going to be out of date. Most of the danger is from unknown threats. If you need to be able to detect Windows malware in your files, use one of the free anti-virus products in the Mac App Store — 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. An anti-malware product from the App Store, such as "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.
    An anti-virus app 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:
    Anti-virus software 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 the software unless a network administrator requires you to do it.
    The ClamXav developer won't try to "upsell" you to a paid version of the product. Other developers may do that. Don't be upsold. For one thing, you should not pay to protect Windows users from the consequences of their choice of computing platform. For another, a paid upgrade from a free app will probably have the disadvantages mentioned in section 7.
    9. 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.
    10. As a Mac user you don't have to live in fear that your computer is going to be infected every time you install an application, read email, or visit a web page. But neither should you have the false idea that you will always be safe, no matter what you do. The greatest harm done by security software is precisely its selling point: it makes people feel safe. They may then feel safe enough to take risks from which the software doesn't protect them. Nothing can lessen the need for safe computing practices.

  • cocozo Level 1 Level 1 (0 points)

    Excellent info Linc, big thanks

  • Barry Fisher Level 3 Level 3 (655 points)

    Excellent info Linc and others about how to prevent from getting Malware/Spyware etc. What those programs are, how you get infected and Mac's systems to prevent it. 


    But no-one has answered the question from the OP about how to tell if you have such software on your mac. And of course the corrallary that if you do, how to get rid of it.

  • MadMacs0 Level 5 Level 5 (4,575 points)

    Barry Fisher wrote:


    But no-one has answered the question from the OP about how to tell if you have such software on your mac. And of course the corrallary that if you do, how to get rid of it.

    I attempted to do that with my contribution, but the OP never got back to us as to why they are asking. Is it unexplained issues or specific suspicions or they just have extra time on their hands to search for something that has a low probability of existence?

  • nickolusroy Level 1 Level 1 (0 points)
    there are no viruses which can affect a Mac.


    This is simply not true. Because less than 10% of computer users are mac users, people who write computer viruses tend not to attack mac operating systems, as their goal is generally to distribute the virus as far and wide as possible.


    To say that mac viruses don't exist is false. Apple doesn't have a magic spell they can cast to prevent malicious attacks, its just far less likely to happen because developers of viruses are far less interested in this tiny user base.

  • Kurt Lang Level 8 Level 8 (35,185 points)

    Name one actual OS X virus. And don't just name it, post a link to a credible source. Good luck.

  • nickolusroy Level 1 Level 1 (0 points)

    "Our bear patrol must be effective, there have been no bear sightings in years!"


    Thats pretty much how your logic is working. But nonetheless, here you go:


  • Kurt Lang Level 8 Level 8 (35,185 points)

    And another so-call security expert who doesn't know the difference between a virus and a Trojan, worm or root kit. Try again.

  • nickolusroy Level 1 Level 1 (0 points)

    I've never claimed to be a security expert. Can you tell me why I'm a "so called security expert" ? I really appreciate your kind and courteous attitude, by the way.


    The sad thing is, you who do claim to be a security expert, are still not correct about this. Here is a proof of concept virus that proves macs are not immune to viruses.


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