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Malware detected by ClamXav

1978 Views 6 Replies Latest reply: Feb 26, 2013 11:19 PM by MadMacs0 RSS
smr.kol Calculating status...
Currently Being Moderated
Feb 26, 2013 1:46 AM

My mid-2010 MacBook Pro has been behaving perfectly, except for a few occasions when I might have imagined that it took a bit longer to open an app or a folder or file. With talk about trojans and all going round, I downloaded recently ClamXav. It has detected and quarantined more than 50 files with a malware identified as "Heuristics.Phishing.Email.SpoofedDomain" from the inbox of my Gmail account. All the mails were from two banks. There were other mails also from the same banks, but were not picked up by the antivirus software. What should I do?

MacBook Pro, OS X Mountain Lion (10.8.2)
  • Linc Davis Level 10 Level 10 (108,110 points)
    Currently Being Moderated
    Feb 26, 2013 9:50 AM (in response to smr.kol)

    What should I do?

     

    Nothing. That's not malware. It may or may not be phishing email, in which case you should delete it from within Mail, not with ClamXav.

     

    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.
    For more information about Gatekeeper, see this Apple Support article.
             
    4. Beyond XProtect and Gatekeeper, 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.
    5. 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 never a good idea, and Java's developers have had a lot of trouble 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.
       
    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 only on well-known, password-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 these guidelines, and you’ll be practically as safe from malware as you can be.

    6. 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.
    7. 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:
      
    ♥♥♥♥♥♥♥♥♥♥♥♥♥♥!!!!!!!H0TBABEZ4U!!!!!!!.AVI♥♥♥♥♥♥♥♥♥♥♥♥♥♥.exe
       
    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.
        
    8. 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.
      
    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.

  • michaelsip4 Level 2 Level 2 (300 points)
    Currently Being Moderated
    Feb 26, 2013 10:52 AM (in response to Linc Davis)

    Allow me to interject

     

    goto to clamxav support site and determine what the message designation represents

    http://www.clamxav.com/BB/viewforum.php?f=1&sid=f451f391441f09e60c92a1338c79bdbf

    However when u search use Heuristics.Phishing as the search parameter

  • michaelsip4 Level 2 Level 2 (300 points)
    Currently Being Moderated
    Feb 26, 2013 11:39 AM (in response to michaelsip4)

    a sample of some of the responsed could be along this line or others.

     

    ZenoAthens wrote: .Trash/10194.emlx     Heuristics.Phishing.Email.SpoofedDomain

     

    I don't know how this could have gotten there, but it's a possible infected e-mail message that is sitting in your Trash Can. I can only guess that this was somehow moved there in after a previous scan which is a bad idea for two reasons.

     

    The word Heuristics means that it wasn't positively identified as a phishing message, just that something about the say it was formatted looked suspicious. These should always be read first to make certain they aren't something important.

     

    Secondly moving it will corrupt the mailbox index.

    Here's my standard guidance on handling such things:  Never use ClamXav (or any other A-V software) to move (quarantine) or delete e-mail. It will corrupt the mailbox index which could cause loss of other e-mail and other issues with functions such as searching. It may also leave the original e-mail on your ISP's e-mail server and will be re-downloaded to your hard drive the next time you check for new mail.   So, if you choose to "Scan e-mail content for malware and phishing" in the General Preferences, make sure you do not elect to either Quarantine or Delete infected files.   When possibly infected e-mail files are found: - Highlight the entry in the ClamXav window's top pane that needs to be dealt with. - Right-click/Control-click on the entry.  - Select "Reveal In Finder" from the pop-up menu.  - When the window opens, double-click on the file to open the message in your e-mail client application.  - Read the message and if you agree that it is junk/spam/phishing then use the e-mail client's delete button to delete it (reading it is especially important when the word "Heuristics" appears in the infection name).  - If you disagree and choose to retain the message, return to ClamXav and choose "Exclude From Future Scans" from the pop-up menu.  - If this is a g-mail account and those messages continue to show up after you have deleted them in the above manner, you may need to log in to webmail using your browser, go to the "All Mail" folder, find the message(s) and use the delete button there to permanently delete them from the server. Then check the "Trash" folder and delete them there.

  • MadMacs0 Level 4 Level 4 (3,345 points)
    Currently Being Moderated
    Feb 26, 2013 6:42 PM (in response to smr.kol)

    smr.kol wrote:

     

    My mid-2010 MacBook Pro has been behaving perfectly, except for a few occasions when I might have imagined that it took a bit longer to open an app or a folder or file. With talk about trojans and all going round, I downloaded recently ClamXav. It has detected and quarantined more than 50 files with a malware identified as "Heuristics.Phishing.Email.SpoofedDomain" from the inbox of my Gmail account. All the mails were from two banks.

    As others have said, the fastest way to get help with ClamXav is to visit the Forum.

     

    One thing that is new for Gmail accounts, is that I finally found a way to permanently delete e-mail without having to use webmail in the All Mail folder. See how here.

  • MadMacs0 Level 4 Level 4 (3,345 points)
    Currently Being Moderated
    Feb 26, 2013 11:19 PM (in response to smr.kol)

    smr.kol wrote:

     

    Thank you so much for all the very useful information. All the files quarantined by ClamXav appear to be routine publicity material from banks. As I am a novice I am not sure about how to return these files from the Quarantine folder in Documents to their original location in Mail without disturbing the latter's index or sequencing system.

    You have already corrupted the maibox index by moving them. As long as you don't need any of them, all you need to do is rebuild each mailbox that that they came from. If you are using Apple Mail, then you do that by highlighting each affected mailbox, in turn, and selecting "Rebuild" from the bottom of the Mailbox menu.

    how should I get rid of ClamXav without disturbing the operating system?

    That depends on where you got it from (AppStore or web site). Everything you need to know about ClamXav can be found from the ClamXav Help menu or as I suggested earlier, dropping by the ClamXav Forum, but I'll save you some time just this once.

     

    Removal of the AppStore version is done in the same manner as any other AppStore app http://support.apple.com/kb/HT4673.

     

    Removal of the Web version requires you to remove the scan engine first which is all explained at FAQ 22. How do I uninstall ClamXav completely?

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