4 Replies Latest reply: Jan 18, 2012 9:39 AM by Klaus1
alexspencer Level 1 Level 1 (0 points)

I want to transfer my files (by USB) from my old computer "PC" to my new macbook pro, but my old cPC had a virus before, and I'm sure even though I already scanned it, there's still some left. I am planning to buy a "Norton Internet Security For Mac 5.0" to make sure this could help to avoid viruses to my mac, but it's for internet. If I won't use any antivirus software does my macbook pro will be harmed?.. any informations, suggestions or advices? thanks,

MacBook Pro
  • 1. Re: A USB inserted from an infected computer will harm my Macbook pro?
    Klaus1 Level 8 Level 8 (44,485 points)

    It might be a good idea to 'clean up' the PC before transferring the files. Viruses that affect Windows do not affect Apple OS X, but read on:




    No viruses that can attack OS X have so far been detected 'in the wild', i.e. in anything other than laboratory conditions.


    It is possible, however, to pass on a Windows virus to another Windows user, for example through an email attachment. To prevent this all you need is the free anti-virus utility ClamXav, which you can download for Tiger from:




    and for Leopard, Snow Leopard and Lion from here:




    Note: If you wish to uninstall ClamXav: keep a copy of the disk image from when you downloaded it, or download it again - the uninstaller is included with the application. To uninstall, quit ClamXav Sentry (if you use it) and make sure it's not set to launch at log in. The uninstaller will remove the engine and any schedules you've got set up, then just drag ClamXav.app to the trash.


    If you are already using ClamXav: please ensure that you have installed all recent  Apple Security Updates  and that your version of ClamXav is the latest available.


    Do not install Norton Anti-Virus on a Mac as it can seriously damage your operating system. Norton Anti-Virus is not compatible with Apple OS X.




    Do not be tricked by 'scareware' that tempts computer users to download fake anti-virus software that may itself be malware.


    Fake anti-virus software that infect PCs with malicious code are a growing threat, according to a study by Google. Its analysis of 240m web pages over 13 months showed that fake anti-virus programs accounted for 15% of all malicious software.


    Scammers trick people into downloading programs by convincing them that their PC is infected with a virus.

    Once installed, the software may steal data or force people to make a payment to register the fake product.

    Beware of PDF files from unknown sources. A security firm announced that by its counting, malicious Reader documents made up 80% of all exploits at the end of 2009.:


    http://www.computerworld.com/s/article/9157438/in which Rogue_PDFs_account_for_80_of_all_exploits_says_researcher




    The appearance of Trojans and other malware that can possibly infect a Mac seems to be growing, but is a completely different issue to viruses.


    If you allow a Trojan to be installed, the user's DNS records can be modified, redirecting incoming internet traffic through the attacker's servers, where it can be hijacked and injected with malicious websites and pornographic advertisements. The trojan also installs a watchdog process that ensures the victim's  (that's you!)  DNS records stay modified on a minute-by-minute basis.


    You can read more about how, for example, the OSX/DNSChanger Trojan works (by falsely suggesting extra codecs are required for Quicktime) here:




    SecureMac has introduced a free Trojan Detection Tool for Mac OS X.  It's available here:




    First update the MacScan malware definitions before scanning. You can also contact their support team for any additional support - macsec@securemac.com


    The DNSChanger Removal Tool detects and removes spyware targeting Mac OS X and allows users to check to see if the trojan has been installed on their computer; if it has, the software helps to identify and remove the offending file. After a system reboot, the users' DNS records will be repaired.


    (Note that a 30 day trial version of MacScan can be downloaded free of charge from:




    and this can perform a complete scan of your entire hard disk. After 30 days free trial the cost is $29.99. The full version permits you to scan selected files and folders only, as well as the entire hard disk. It will detect (and delete if you ask it to) all 'tracker cookies' that switch you to web sites you did not want to go to.)


    A white paper was published on the subject of Trojans by SubRosaSoft, available here:


    http://www.macforensicslab.com/ProductsAndServices/index.php?main_page=document_ general_info&cPath=11&products_id=174


    Also, beware of MacSweeper and MacDefender (also goes under the name of MacProtector, MacGaurd, MacSecurity or MacShield) :


    These are malware that misleads users by exaggerating reports about spyware, adware or viruses on their computer in an attempt to obtain payment.


    Mackeeper is equally worthless and should also be avoided. Again, the developer seeks to obtain payment for an application that does nothing that free utilities do not also offer, and in many cases it will also mess up your system.


    You can keep up to date, particularly about malware present in some downloadable pirated software, at the Securemac site:






    Adding Open DNS codes to your Network Preferences, should give good results in terms of added security as well as speed-up:


    Open System Preferences/Network. Double click on your connection type, or select it in the drop-down menu, and in the box marked 'DNS Servers' add the following two numbers:



    (You can also enter them if you click on Advanced and then DNS)


    Sometimes reversing the order of the DNS numbers can be beneficial in cases where there is a long delay before web pages start to load, and then suddenly load at normal speed:




    There may be other ways of guarding against Trojans, viruses and general malware affecting the Mac, and alternatives will probably appear in the future. In the meantime the advice is: be careful where you go on the web and what you download!




    If you think you may have acquired a Trojan, and you know its name, you can also locate it via the Terminal:


    http://theappleblog.com/2009/04/24/mac-botnet-how-to-ensure-you-are-not-part-of- the-problem/


    Although any content that you download has the possibility of containing malicious software, practising a bit of care will generally keep you free from the consequences of anything like the DNSChanger trojan.

    1. Avoid going to suspect and untrusted Web sites, especially p'orn'ography sites.


    2. Check out what you are downloading. Mac OS X asks you for you administrator password to install applications for a reason! Only download media and applications from well-known and trusted Web sites. If you think you may have downloaded suspicious files, read the installer packages and make sure they are legit. If you cannot determine if the program you downloaded is infected, do a quick Internet search and see if any other users reported issues after installing a particular program.


    3. Use an antivirus program like ClamXav. If you are in the habit of downloading a lot of media and other files, it may be well worth your while to run those files through this AV application.


    4. Use Mac OS X's built-in Firewalls and other security features.


    5.  Peer-to-peer sharing applications and download torrents (such as the now defunct LimeWire) supplying pirated software, movies etc are hotbeds of potential software issues waiting to happen to your Mac. Everything from changing permissions to downloading trojans and other malicious software can be acquired from using these applications. Similar risks apply to using Facebook, Twitter, MySpace, YouTube and similar sites which are prone to malicious hacking:  http://news.bbc.co.uk/1/hi/technology/8420233.stm


    6. Resist the temptation to download pirated software. They can contain Botnet Trojans.  SecureMac offer a simple and free tool for the removal of the iBotNet Trojan available here:




    YOUR PRIVACY ON THE INTERNET and the latest risks to look out for:


    There is the potential for having your entire email contact list stolen for use for spamming:




    And if you are using iPhone Apps you are also at risk of losing all privacy:


    http://www.engadget.com/2010/10/03/hacker-claims-third-party-iphone-apps-can-tra nsmit-udid-pose-se/


    The advent of HTML5  may also be a future threat to internet privacy:




    Security of OS X generally:






    Security Configuration for Version 10.5 Leopard:




    NOTE: Apple's Snow Leopard and Lion operating systems silently update the malware protection built into Mac OS X to protect against a backdoor Trojan horse that can allow hackers to gain remote control over your treasured iMac or MacBook: Macs running Snow Leopard or Lion now check for new malware definitions daily, allowing Apple to quickly deploy protection from threats before they have a chance to spread.

    Few malicious titles actually exist for Mac OS X, and those that do rely almost entirely upon duping users to install software that pretends to be legitimate.




    However, if you are running Lion Server:


    Apple's new server operating system -- OS X Lion -- is so inherently insecure that Stamos recommends keeping it off the network altogether and using Macs only as standalone machines connected to IP or Windows networks, not those designed for Macs.

    The Mac Server's networking protocols -- especially DHX User Authentication -- are designed for ease of use, not security. It is trivial, Stamos said, for hackers to set up a Mac user to download a file that will overflow the buffer protecting the heap segment of the server's memory, allowing the file's malicious payload to run uncontrolled in the server's memory and give itself whatever access rights it wants.


  • 2. Re: A USB inserted from an infected computer will harm my Macbook pro?
    thomas_r. Level 7 Level 7 (27,930 points)

    You do not need to worry about the viruses your Windows machine may have had, they cannot affect your Mac.  As to Norton, that has a very bad reputation around here.  I would avoid it.


    For more information on this topic, see my Mac Malware Guide.


    (Note that my pages contain links to other pages that promote my services, and this should not be taken as an endorsement of my services by Apple.)

  • 3. Re: A USB inserted from an infected computer will harm my Macbook pro?
    Ralph Landry1 Level 7 Level 7 (32,450 points)

    Klaus, that was excellent...printed a copy for the files as I can never remember all of those addresses.


    One addition you might consider - the uninstall procedure of the author of MacKeeper does not uninstall but leaves nasty little files that keep up the problems...have to go to Phile Stokes's procedure to actual clean up the mess.

  • 4. Re: A USB inserted from an infected computer will harm my Macbook pro?
    Klaus1 Level 8 Level 8 (44,485 points)

    Thanks Ralph, that was a copy of my User Tip available here:





    (I have ClamXav set to scan incoming emails, but nothing else.)


    First update the MacScan malware definitions before scanning. You can also contact their support team for any additional support - macsec@securemac.com



    To which the following could be added:


    Security of OS X generally:






    Security Configuration for Version 10.5 Leopard:




    This Blog entry is also worth a read:




    Has your Mac been infected by a Botnet? Go here http://botnetchecker.com/  (do not enter any information) and it will tell you.


    UPDATES: How safe is your smartphone? (Android is the top malware collector)

    Another source of malware, apart from sites like Facebook and Hotmail, is the Android Marketplace:

    More than 50 applications available via the official Android Marketplace were initially found to contain a virus.

    Analysis suggests that the booby-trapped apps may have been downloaded up to 200,000 times. The apps are also known to be available on unofficial Android stores too. Once a booby-trapped application is installed and run, the virus lurking within, known as DroidDream, sends sensitive data, such as a phone's unique ID number, to a remote server. It also checks to see if a phone has already been infected and, if not, uses known exploits to bypass security controls and give its creator access to the handset. This bestows the ability to install any code on a phone or steal any information from it.

    Remote removal of the booby-trapped apps may not solve all the security problems they pose. The remote kill switch will not remove any other code that may have been dropped onto the device as a result of the initial infection.

    Moreover, more than 99% of Android phones are potentially leaking data that, if stolen, could be used to get the information they store online.



    The data being leaked is typically used to get at web-based services such as Google Calendar.

    The open nature of the Android platform was a boon and a danger, and as Facebook have already discovered it is also a very attractive criminal playground.


    Smartphones and social networking sites are likely to become the next big target for cyber criminals, according to a security industry report.

    Symantec's annual threat analysis warns that the technologies are increasingly being used to spread malicious code.

    Users of Facebook, Twitter and Google's mobile operating system, Android, are said to be particularly vulnerable.

    In several cases, the security holes were exploited and used to install harmful software on Android handsets - suggesting that criminals now view smartphone hacking as a potentially lucrative area, and Android is still in the firing line:


    Android: it's getting worse: Juniper found a 400% increase in Android malware from 2009 to the summer of 2010.  We have since seen exponential grow in Android malware over the last several months. The Juniper Global Threat Center found that the months of October and November are shaping up to see the fastest growth in Android malware discovery in the history of the platform. The number of malware samples identified in September increased by 28% over the number of the known Android malware samples. October showed a 110% increase in malware sample collection over the previous month and a striking 171% increase from what had been collected up to July 2011.


    At least six different varieties of malware were discovered hidden in applications that were distributed through a Chinese download service.

    Several pieces of malware were also found on iPhones, however only devices that had been "jailbroken" to bypass Apple's security were affected.

    The company's process of pre-vetting all new applications is believed to have spared its devices from a major attack.

    The company estimates that one in six links posted on Facebook pages are connected to malicious software.


    to which Facebook has responded:

    "Facebook and Internet security company Web of Trust (WOT) will provide Facebook users with a feature that protects them against dubious Web links, the companies said this week.

    When a Facebook user clicks on a link that leads to a page with a poor reputation rating given by the WOT community, the user will receive a warning message. Typically, the sites with a poor reputation are known for phishing, untrustworthy content, fraudulent services or other scams."



    Newly discovered malicious software dubbed "MACDefender" takes aim at users of the Mac OS X operating system by automatically downloading a file through JavaScript. But users must also agree to install the software, leaving the potential threat limited.


    The new MACDefender malware was first noted on April 30, 2011 by users of the Apple Support Communities, and was highlighted by antivirus company Intego. If the right settings are enabled in Apple's Safari browser, MACDefender can be downloaded to a system after a user clicks a link while searching the Internet.


    "When a user clicks a link after performing a search on a search engine such as Google, this takes them to a web site whose page contains JavaScript that automatically downloads a file," Intego said. "In this case, the file downloaded is a compressed ZIP archive, which, if a specific option in a web browser is checked (Open 'safe' files after downloading in Safari, for example), will open."


    However, users must still agree to install the malware after it downloads. After the ZIP file is extracted, users are presented with the "MACDefender Setup Installer," at which point they must agree to continue and provide an administrator password.


    Because of the fact that users must agree to install the software and provide a password, Intego categorized the threat with MACDefender as "low."


    Users on Apple's support forums advise killing active processes from the application using the Mac OS X Activity Monitor. MACDefender can then be deleted from the Applications folder by dragging it into the trash.


    The malware is not to be confused with MacDefender, the maker of geocaching software including GCStatistic and DTmatrix. The company noted on its site it is not affiliated with the malware.


    Malware spreads through search engines like Google via a method known as "SEO poisoning." The sites are designed to game search engine algorithms and show up when users search for certain topics.


    The latest threat to  the Mac OS is the Weyland-Yutani BOT, which is described as a DIY crimewave kit that supports web injects and form grabbing in Firefox; however both Chrome and Safari will soon follow.  'Form grabbing' is a way of collecting passwords:




    Apple's Snow Leopard and Lion operating systems  silently update the malware protection built into Mac OS X to protect against a backdoor Trojan horse that can allow hackers to gain remote control over your treasured iMac or MacBook: Macs running Snow Leopard or Lion now check for new malware definitions daily, allowing Apple to quickly deploy protection from threats before they have a chance to spread.

    Few malicious titles actually exist for Mac OS X, and those that do almost entirely rely upon duping users to install software that pretends to be legitimate, however A new version of an existing Trojan Horse posing as a legitimate Flash Player installer (named “Flashback.A” by a security firm) is designed to disable updates to the default Mac OS X anti-malware protection system, potentially leaving the system open to the manual installation of other malware without any system warnings. In order to prevent a potential infection with “Flashback” Trojans, Mac users are advised to obtain their copy of Adobe Flash Player directly from Adobe’s official website and to disable the "Open 'safe' files after downloading" option in Apple's Safari browser to avoid automatically running files downloaded from the Internet.


    http://www.appleinsider.com/articles/11/10/19/fake_adobe_flash_malware_seeks_to_ disable_mac_os_x_anti_malware_protection.html


    Additional reading:


    "Antivirus Software On Your Mac: Yes or No?"