Mac Virus/Malware FAQ

Discussion in 'Mac Basics and Help' started by stridemat, Jul 23, 2014.

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  1. stridemat, Jul 23, 2014
    Last edited by stridemat: Jul 23, 2014

    stridemat Moderator

    stridemat

    Staff Member

    Joined:
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    UK
    #1
    Credit should go to GGJstudios for the original text.

    You DON'T have a virus on your Mac!
    If you want to know why this is true, read on.

    The term "virus" is commonly but erroneously used to refer to all types of malware, adware, and spyware programs that do not have the reproductive ability of a true virus.

    The bottom line is this: as a Mac user, your chances of being affected by a virus, trojan or other malware are extremely slim, unless you've been careless about where you get software and when you enter your administrator password.

    If you're experiencing a problem or unexpected behavior with your Mac, there's better than a 99.9% chance that it's something other than a virus or other malware.

    MALWARE TERMINOLOGY
    From Symantec:


    What is scareware?
    Another type of hoax is referred to as scareware. It's a bogus virus warning that pops up when visiting some websites, and looks something like this or this (on iPads). If you take a close look, you'll see the popup refers to a Windows system, which obviously doesn't relate to Mac OS X. It can't harm your Mac at all. Just close the site, clear your browser's cache and cookies, and you'll be fine. Sometimes these scareware sites will generate a never-ending loop of popups, to the point that you must Force Quit your browser. Such scareware sites are usually intended to lure a Windows user into clicking the links to install bogus "antivirus" software, which is typically a trojan. Even if you click the links on a Mac system, it can't install anything, because Windows executable files can't run on Mac OS X.​

    There are NO viruses in the wild that affect Mac OS X at this time.
    If this changes, I will update this post. According to noted computer virus expert Paul Ducklin, in order for a virus to be considered in the wild, "it must be spreading as a result of normal day-to-day operations on and between the computers of unsuspecting users." This definition excludes "proof of concept" code that is used in a testing situation under strictly controlled conditions, and which poses zero threat to average computer users.

    In the past, there have been a few viruses that ran on older versions of the Mac operating system (Mac OS 9 and earlier), but they do not run on any version of Mac OS X. Like every other OS, Mac OS X is not immune to malware threats, this situation could change at any time, but if a new virus is discovered, the news media, forums, blogs, etc. will be instantly buzzing with the news. See update below.*

    There are trojans that can affect Mac OS X,
    but these must be downloaded and installed by the user, which usually involves entering the user's administrator password. Also, Mac OS X will give you a warning when you first launch an app you downloaded from the web. Trojans can easily be avoided by the user exercising common sense and caution when installing applications. A common source of trojans is pirated software, typically downloaded from bit torrent sites.​

    ANTIVIRUS APPS

    Having virus protection software on your Mac is pointless, as far as protecting your Mac from true viruses, since current antivirus software cannot detect a Mac virus that doesn't yet exist, because they simply don't know what to look for. It is possible to have a virus-infected file reside on your hard drive, but since a Windows virus (like any Windows program) can't run in native Mac OS X, it would be harmless to your Mac and could not spread.

    If your situation requires you to run a 3rd-party antivirus app:
    • ClamXav is one of the best choices, since it isn't a resource hog, detects both Mac and Windows malware and doesn't run with elevated privileges. You can run scans when you choose, rather than leaving it running all the time, slowing your system. ClamXav has a Sentry feature which, if enabled, will use significant system resources to constantly scan. Disable the Sentry feature. You don't need it. Also, when you first install ClamXav, as with many antivirus apps, it may perform an initial full system scan, which will consume resources. Once the initial scan is complete, periodic on-demand scans will have much lower demands on resources.
    • Sophos should be avoided, as it could actually increase your Mac's vulnerability, as described here and here... and here.
    • iAntiVirus has a bogus malware definitions list, making their detection accuracy untrustworthy. They also make inaccurate claims about the existence of Mac malware, in order to hype the need for their product. This post will give details.

    WHAT SECURITY STEPS SHOULD I TAKE?

    • DON'T install pirated software, or software from untrusted or unknown sites.
    • You can't infect your Mac simply by visiting a website, opening an email attachment, or connecting to a network. You should, however, exercise reasonable caution when doing these things.
    • Be careful about giving others access to your computer, as they could download and install malware.
    • For Safari users: go to Safari > Preferences > Security > Enable Java (leave this unchecked, unless you're visiting a trusted site that requires it)
    • Make sure you install software updates when they're released, including OS X and apps
    • Only install updates from an installed app, the Mac App Store or directly from a software developer's site. Never install an update to software when prompted to do so by an advertisement on a website or an email.
    • Use ad-blockers to minimize exposure to malicious sites
    • Use trusted DNS servers
    • Go to System Preferences > Security > Firewall and make sure your built-in firewall is enabled
    • Read Mac Security Suggestions compiled by munkery

    WHAT ABOUT SENDING FILES TO WINDOWS USERS?
    Some users choose to run antivirus such as ClamXav on their Mac to scan for Windows viruses (it also scans for Mac threats), so the Mac user can't pass a virus-infected file to a Windows user. However, a more prudent approach is for every Windows user to be protected by their own AV software, to guard against viruses from any source, not just those that might come from a Mac user.

    Running anti-virus on your Mac to protect Windows users from malware is like covering your mouth when you cough in front of the kids, then sending them out without flu shots to a school where a flu epidemic is spreading like wildfire. Great! They might not catch anything from you, but you've left them vulnerable to the greater risk. It's wiser to make sure they have flu shots, so they're protected from infection, whether it be from you or from other people.

    If you really want to help your Windows friends, encourage them to get their own anti-virus protection installed, or offer to install it for them.​
    WHY AM I BEING REDIRECTED TO OTHER SITES?

    Some users experience a problem with being directed automatically to sites that they didn't intend to visit. This may also occur when searching with Google. You don't have a virus! It's a problem with your DNS settings, either in your Mac or in your router. Try resetting your router. Here's how to fix the problem in Mac OS X:


    *UPDATE - RECENT THREATS IN THE NEWS

    As has already been stated, any appearance of significant new security threats to Mac OS X will make news headlines:

    MacDefender or MacSecurity or MacProtector or MacGuard installation package
    Apple has issued a knowledge base article on this issue, found here:

    How to avoid or remove Mac Defender malware
    Further information on MacDefender:

    trojan.osx.boonana.a Trojan
    On Oct. 26, 2010, Mac security site SecureMac posted this security bulletin:
    As with all trojans, this requires the user to unwittingly invite the infection by deliberate action (in this case, clicking on a fake video link). You cannot be infected by this trojan if you don't click on the appropriate link. You can eliminate this threat by disabling Java in your web browser.
     
  2. brdeveloper macrumors 68020

    brdeveloper

    Joined:
    Apr 21, 2010
    Location:
    Brasil
    #2
    Well, actually being virus-free is pretty easy even on Windows these days. When someone says "Macs don't get virus!" it looks more like an advertising than a preventive approach. Even Windows is almost virus free these days. The problem is software not capable of reproducing itself like adwares, spywares, trojans, rootkits, etc.

    I'm a little bit afraid for never having got a malware on my Macs. Actually I don't know if something is being tracked by some hidden application/service.
     
  3. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #3
    All OS X malware that has ever existed in the wild can be easily avoided by practicing safe computing. It is really quite rare to even encounter OS X malware, unless you're being reckless with where you get software that you install.
     
  4. squonk2 macrumors newbie

    Joined:
    Dec 5, 2014
    #4
    A Trojan...?

    Thank you for all your valuable information, GGJstudios. I'm a new member and have been reading all your posts on the forums regarding viruses and malware.

    While I always use the safe computing practices you've described, my wife (not technically savvy) does not. I'm fearful she might have invited a Trojan without knowing.

    She was attempting to send an Evite online (a site she uses frequently) when a shaded gray popup window asked her to enter the word/phrase displayed in that window into an open space below. This has never happened to her on this site before. Unknowingly, she entered the phrase and her entire iMac screen started flashing black & white. She immediately quit her browser. She relayed this story to me, so I did not see it but it all sounds concerning.

    I am willing to run any recommended antivirus/malware software if warranted. Her iMac has been shut off since and I'm looking to the knowledge of others as to how I should proceed.

    Thank you for any help/suggestions!
     
  5. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #5
    This is a security method that many sites use to make sure their site is being accessed by a real person, and not a bot (automated software). It's called a CAPTCHA test, and it's completely harmless.

    It sounds like the site may have had a problem properly displaying the page. It doesn't sound like anything related to any known malware. Clear your browser's cache and cookies and try it again. Chances are very good that it's just a glitch on the site, and nothing to be concerned about.

    If you need to run a scan for your peace of mind, you can install ClamXav and run a scan. I doubt it will find anything, though.
     
  6. squonk2 macrumors newbie

    Joined:
    Dec 5, 2014
    #6
    Thank you, GGJstudios. I appreciate your expertise!
     
  7. satcomer macrumors 603

    satcomer

    Joined:
    Feb 19, 2008
    Location:
    The Finger Lakes Region
    #7
    Tales really consider using a free personal account at OpenDNS because you can set it up to block known Trojan hosting sites with their Phisphing Protection.
     
  8. Dave Braine macrumors 68040

    Dave Braine

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    Mar 19, 2008
    Location:
    Warrington, UK
  9. chown33 macrumors 604

    Joined:
    Aug 9, 2009
    Location:
    Brobdingnag
    #9
    It should be a Sticky Wiki. Or a Wiki Sticky.
     
  10. 2012Tony2012 macrumors 6502a

    2012Tony2012

    Joined:
    Dec 2, 2012
    #10
    And what about if a person does not practise safe computing, how can that person protect themselves from getting nasties?
     
  11. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #11
    Antivirus apps may catch some of the malware such a user might encounter, but not all. If a user is determined to be careless about how thy use their computer, there is no method of protection that will be completely effective. Given that safe computing is not cumbersome, why wouldn't anyone choose to not practice it?
     
  12. 2012Tony2012 macrumors 6502a

    2012Tony2012

    Joined:
    Dec 2, 2012
    #12
    So in other words....if someone doesn't practice "safe computing", then their Mac can indeed get infected?
     
  13. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #13
    It is very unlikely that an average Mac user will ever encounter malware, unless they're regularly engaging in risky activities, such as installing pirated software. It is possible, however, for any Mac to be infected if the user doesn't practice safe computing, even if they have antivirus software installed.
     
  14. 2012Tony2012 macrumors 6502a

    2012Tony2012

    Joined:
    Dec 2, 2012
    #14
    Interesting....so there are virus on Mac that someone may get if they do not practice safe computing.

    And there are Mac apps that are virus', for example pirated apps for Mac?
     
  15. crjackson2134 macrumors 68040

    crjackson2134

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    Charlotte, NC
  16. 2012Tony2012 macrumors 6502a

    2012Tony2012

    Joined:
    Dec 2, 2012
    #16
    So not a single Virus exists for Mac?:eek:
     
  17. chown33 macrumors 604

    Joined:
    Aug 9, 2009
    Location:
    Brobdingnag
    #17
    This is answered in the first post.

    Read the definition of a virus by finding the "What is a virus?" heading.

    Then find the words "in the wild" and read what it says there.

    If the above doesn't answer your question, then ask a more specific question.

    If you haven't read the first post completely, then please do that before asking additional questions. There's no purpose in asking questions that are already answered.
     
  18. Prplehz76 macrumors newbie

    Prplehz76

    Joined:
    May 24, 2018
    Location:
    Bay Area
    #18
    There is a whole grouping of files I’ve found on my Mac that ‘cannot be opened due to no program exists to use it with’ could this be a “virus” or a program installed to gain access via sharing and cause havoc? I’m struggling with sharing process’s, tcp, AirPlay, airport, and netbios showing an open connection on my Mac even though all sharing portions are OFF, my WiFi, Bluetooth, etc are OFF, and.... my firewall is set to the highest possible setting allowed! Could this be a Trojan, or is this an actual remote user/spyware, or could this just be a bug in some code? I’ve gone from having plenty of room on my hard drive to having next to nothing available. Would just resetting the Mac back to default correct this and forget trying to surgically removing what’s gone wrong?
    --- Post Merged, Jul 2, 2018 ---
    Ps, I understand this post is dated 2014 but I’m looking for answers to save my Mac.....
     
  19. Gregg2 macrumors 603

    Joined:
    May 22, 2008
    Location:
    Milwaukee, WI
    #19
    Well, do you think the problem is that these files are bogus? Or, do you think the files are good, and the apps you created with them are present? You haven't fully presented the problem.
     
  20. mpainesyd macrumors 6502

    mpainesyd

    Joined:
    Nov 29, 2008
    Location:
    Sydney, Australia
    #20
    If you have been updating macOS/OSX for several years it is likely that there are some old files hanging around are no longer associated with any apps. However the filling up of your hard drive is a puzzle.
    I did have a problem a while ago where I found copying a file from one Mac to the external hard drive on another Mac created multiple copies of that file and I had to Force Quit finder to stop it. Have you looked for multiple copies of files?

    EtreCheck.app is useful for diagnosing problems on a Mac.
     
  21. Prplehz76 macrumors newbie

    Prplehz76

    Joined:
    May 24, 2018
    Location:
    Bay Area
    #21
    FF726DFB-0890-43A6-A58E-27BBA4440C3B.png
    Well to give some background I had moved with my bf at the time now fiancé from the city to a very rural area where there is no WiFi and we have to rely on our cell phones and hot spot. I’ve worked in the Silicon Valley for startups for over ten years and I’m an accountant but a computer nerd at heart and I actually handle the operations side of accounting, long story short Im not shy around computers and am the family IT person and for the past two years have had to learn networking because of all going on. We hired an IT person a year ago too. So like I was saying since we moved here it started with my iPhone 6 Plus at the time began acting strange. Freezing, icons at the top shifting. My passwords would stop working and it became a daily thing of resetting all passwords, I got a new phone 6s plus. It only got worse. My keyboard would delete words as I typed them. It was happening to all of us but mainly me. It started getting really strange. All our devices and email began to be inundated with porn and some was worth me calling a friend in law enforcement. My phones old and new on day just became disabled. Poof! My Mac would tell me someone was logged in, we talked to Apple, I’ve reset all devices more than once, replaced SIM cards, my Mac then was disabled (my boyfriend had an android and a surface if this matters. My car stereo was an android) I have been VERY conservative no 3rd party software, my devices were work related and so I kept them clean and updated. The IT guy said he’s never seen devices in such good condition. He reset everything but we got new phones 7plus and I switched carriers. Att to Verizon! It calmed down for a bit then it started again and Python has been installed(?) my iCloud account at times was inaccessible. I’ve learned command line and it’s th only thing that keeps me sane and Apple has confirmed there is some developer stuff being accessed but also a lot of native apple stuff. My MacBook Pro retina is a developer system my work gave me as a gift and so Xcode & Automater, text wrangler are all installed and I suspect they play a huge part in the problem. I can tell you that with WiFi off, sharing off, Finder has been rearranged magically, I’ve turned my firewall on highest settings, and I’ve attached a screenshot of my Mac presently. This is actually pretty quiet. Sometime each interface will show an established connection with everything off. And there are constantly signs of Microsoft programs or processes running my word and excel have become unusable. The newest since yesterday on my phone the app called ‘Mr Putt’ appears under Cellular but no where else. I do not own any app by this name
    --- Post Merged, Jul 2, 2018 ---
    I can’t upload the pictures showing my Mac right now but under Sudo in the terminal using NEttop or lsof -I interfaces lo0 process ‘node’ and Wifiagent have an established connection, awdl0 mDNS respnder is on. Web pages will be obviously spoofed. There is a ddglot of signs of DDos attack. My keyboard is being hijacked again. So let me know what I can provide to help pinpoint the culprit or is there a command I can use that will help me?

    Also port 1720 is always open I can’t figure out what’s causing it.

    Beam.smp.80 has 24 processes open under lo0 via tcp localhost

    Launchd has 6 processes using both ups/tcp two of which are river rock and 4 are using a hidden ipv4 address *:625<->*:* the other s same but numbs inside of 138, Xcscontrol tcp4 via localhost.

    S
    Thank you!!
    --- Post Merged, Jul 2, 2018 ---

    Rereading this my keyboard was being hijacked or something and some of what I said was rearranged. Hopefully you guys get the gist of what I’m dealing with.
     
  22. hobowankenobi macrumors 6502a

    Joined:
    Aug 27, 2015
    Location:
    on the land line mr. smith.
    #22
    Here we go again...

    One of three things:

    • Trolling.
    • Seriously in over your head, doing and troubleshooting things you have no business messing with.
    • The North Koreans are coming after you very, very hard.

    No matter which one it is, I doubt anybody here can solve your issues.
     
  23. Gregg2 macrumors 603

    Joined:
    May 22, 2008
    Location:
    Milwaukee, WI
    #23
    Perception of what the problem might be is still not clear. Rambling "response" to my questions did not address them.
     
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