Failed installation of Avast

Do not install Avast.

If Avast won't install, that's a blessing in disguise. It's the worst of all the bad Mac anti-virus software out there. It has had a serious problem with false positives for years, among other things sporadically identifying as malicious a particular file that is part of Mac OS X since at least 2009. It has recently included an adware component (see Avast installs adware!), and has deals with known adware distributor download.com. Worst of all, Avast is hijacking the security certificates of HTTPS sites in a very irresponsible manner that actually reduces the security of your browsing (see Avast’s man in the middle). Never install Avast!

(Fair disclosure: I may receive compensation from links to my sites, TheSafeMac.com and AdwareMedic.com.)

• Non-Apple "anti-virus" products are worthless and will prevent your Mac from working as designed. Some such products are malicious. "Avast" is not the worst of them, but it comes close.
• Nothing in the world can prevent you from succumbing from "phishing" scams.

There will always be threats to your information security associated with using any Internet - connected communications tool:

1. You can mitigate those threats by following commonsense practices
2. Delegating that responsibility to software is an ineffective defense
3. Assuming that any product will protect you from those threats is a hazardous attitude that is likely to result in neglecting point #1 above.

OS X already includes everything it needs to protect itself from viruses and malware. Keep it that way with software updates from Apple.

A much better question is "how should I protect my Mac":

• Never install any product that claims to "clean up", "speed up", "optimize", "boost" or "accelerate" your Mac; to "wash" it, "tune" it, or to make it "shiny". Those claims are absurd.

  Such products are very aggressively marketed. They are all scams.

• Never install pirated or "cracked" software, software obtained from dubious websites, or other questionable sources.
  • Illegally obtained software is almost certain to contain malware.
  • "Questionable sources" include but are not limited to spontaneously appearing web pages or popups, download hosting sites such as C net dot com, Softonic dot com, Soft pedia dot com, Download dot com, Mac Update dot com, or any other site whose revenue is primarily derived from junk product advertisements.
  • If you need to install software that isn't available from the Mac App Store, obtain it only from legitimate sources authorized by the software's developer.
• Don’t supply your password in response to a popup window requesting it, unless you know what it is and the reason your credentials are required.
• Don’t open email attachments from email addresses that you do not recognize, or click links contained in an email:
  • Most of these are scams that direct you to fraudulent sites that attempt to convince you to disclose personal information.
  • Such "phishing" attempts are the 21st century equivalent of a social exploit that has existed since the dawn of civilization. Don’t fall for it.
  • Apple will never ask you to reveal personal information in an email. If you receive an unexpected email from Apple saying your account will be closed unless you take immediate action, just ignore it. If your iCloud, iTunes, or App Store account becomes disabled for valid reasons, you will know when you try to buy something or log in to this support site, and are unable to.
• Don’t install browser extensions unless you understand their purpose:

  Go to the Safari menu > Preferences > Extensions. If you see any extensions that you do not recognize or understand, simply click the Uninstall button and they will be gone.

• Don’t install Java unless you are certain that you need it:
  • Java, a non-Apple product, is a potential vector for malware. If you are required to use Java, be mindful of that possibility.
  • Java can be disabled in System Preferences.
  • Despite its name JavaScript is unrelated to Java. No malware can infect your Mac through JavaScript. It’s OK to leave it enabled.
  • The same precaution applies to Adobe Flash Player. Newly discovered Flash vulnerabilities appear almost weekly.
• Beware spontaneous popups: Safari menu > Preferences > Security > check "Block popup windows".
  • Popup windows are useful and required for some websites, but unsolicited popups are commonly used to deceive people into installing unwanted software they would never intentionally install.
  • Popups themselves cannot infect your Mac, but many contain resource-hungry code that will slow down Internet browsing.
  • If you ever receive a popup window indicating that your Mac is infected with some ick or that you won some prize, it is 100% fraudulent. Ignore it.
  • The same goes for a spontaneously appearing dialog insisting that you upgrade your video player right this instant. Such popups are frequently associated with sites that promise to deliver "free" movies or other copyrighted content that is not normally "free".
  • The more insistent it is that you upgrade or install something, the more likely it is to be a scam. Close the window or tab and forget it.
• Ignore hyperventilating popular media outlets that thrive by promoting fear and discord with entertainment products arrogantly presented as "news". Learn what real threats actually exist and how to arm yourself against them:
  • The most serious threat to your data security is phishing. Most of these attempts are pathetic and are easily recognized, but that hasn't stopped prominent public figures from recently succumbing to this age-old scam.
  • OS X viruses do not exist, but intentionally malicious or poorly written code, created by either nefarious or inept individuals, is nothing new.
  • Never install something without first knowing what it is, what it does, how it works, and how to get rid of it when you don’t want it any more.
  • If you elect to use "anti-virus" software, familiarize yourself with its limitations and potential to cause adverse effects, and apply the principle immediately preceding this one.
  • Most such utilities will only slow down and destabilize your Mac while they look for viruses that do not exist, conveying no benefit whatsoever - other than to make you "feel good" about security, when you should actually be exercising sound judgment, derived from accurate knowledge, based on verifiable facts.
• Do install updates from Apple as they become available. No one knows more about Macs and how to protect them than the company that builds them.

Summary: Use common sense and caution when you use your Mac, just like you would in any social context. There is no product, utility, or magic talisman that can protect you from all the evils of mankind.

joakley wrote:

I didn't want this thread to focus on anti-virus. Really I was just hoping for some suggestions on how to get around an ornery installer which happens to be anti-virus software. But since no-one has answered, I'm guessing the issue is very specific to my friend's situation, and not easily answerable.

Yes, without more information about the system in question, it's hard to say whether this is something wrong with the system itself or with the Avast installer. It sounds like you took some good steps. The only thing that would concern me is the fact that the drive needed repairing... with a modern hard drive, that often means that the hard drive is dying, which could explain the issue. Or it might not.

I guess all this leads the wider question of what's the proper thing to do when helping not-so-savvy users stay out of trouble?

Education is the key. There is no software that can guarantee protection, and anyone relying on software to protect them will get infected with something - malware or adware - sooner or later. Mac OS X already detects all currently known malware. New malware won't be detected by either Mac OS X or anti-virus software, and it's a toss-up as to which might protect you first following the discovery of new malware. As to adware, nothing does a great job of blocking it.

However, learning what to be skeptical of and not opening things that are suspicious is as close to a guarantee of not getting infected as anything can be. Rather than assuming that folks who aren't tech savvy can't learn, it's important to try to teach them.