Unwanted software: Don't get more than you bargained for with free downloads

Unwanted software are programs that are downloaded—often unknowingly as part of a software bundle—that can cause serious problems for computer users. Research into unwanted software infection rates finds that at least tens of millions of computers are infected. Unwanted software is associated with billions of dollars in fraud every year.

How does unwanted software affect consumers?

A consumer’s first inkling that her computer is infected with unwanted software may be when she opens her Internet browser and finds that the browser’s default search engine or homepage has been changed without her consent. In other cases, the unwanted software may cause new tabs to automatically load in the browser, pop-up windows to appear, or even change the browser itself (such as by adding a “toolbar” or extension). Another common symptom of unwanted software is when ads start to appear where they aren’t expected (such as weight loss ads on a children’s website or on browser error screens). Additionally, another form of unwanted software are so-called “PC cleaners” or other programs that claim to speed up your computer’s performance.

Consumers can often be confused about the source of this behavior. First, unwanted software often waits several weeks after download to affect the consumer, meaning that a consumer is unlikely to connect the downloaded software with the problems with their browser. In addition, unwanted software can be hard to find and delete—this software often masks its filename so consumers can’t find it and can regenerate even if it gets deleted.  

While unwanted software can appear to be simply an annoyance that detracts from the experience of using a browser, these dangerous downloads in fact pose a significant security risk to consumers’ personal information. Often, such software will disable security protections and settings to take control of a consumer’s computer, leaving that computer vulnerable to hackers and data thieves.

How prevalent is unwanted software?

Unwanted software has been around for some time, but in recent years, it has become an even bigger concern for Internet users. 

For example, a May 2015 study by Google, UC Berkeley, and UC Santa Barbara found that tens of millions of visitors to Google’s serviceshad unwanted adware installed on their computer. Within that group, half had at least two, and nearly one-third of users had at least four such programs infecting their machines. And that’s just for one type of unwanted software infection. Unwanted software was the source of nearly 20% of complaints from Chrome users alone in 2014.

A similar study by security firm Namogoo found that 15-30% of e-commerce website visitors were infected with malware that causes them to view injected ads, malicious links and fraudulent spyware on otherwise legitimate sites.

Research conducted by security firm WhiteOps found that unwanted software such as ad injectors are a significant contributor to the $7.2 billion in ad fraud that occurs every year.

How can you spot unwanted software?

The following are telltale signs of unwanted software:

  • “Express” setup options for software. When installing new software, be wary when you’re prompted to use “express” (or similarly worded) setup options. This could allow the program to install unwanted software. Instead, consider a “custom” setup so that you have control over what exactly is being installed.

  • Pre-checked boxes. When installing one program (say, a PDF reader), you may notice a pre-checked box offering to install another program (like a search toolbar or antivirus) at the same time. Make sure you review these pre-checked options and uncheck those boxes before continuing setup if you don’t know what they are or they look suspicious.

  • No “I decline” option. When installing a new program, you may be prompted to accept an end-user licensing agreement (EULA) as part of the installation. If there’s no “I decline” option with the EULA, or if you’re unable to uncheck the “I accept” box, it could be a red flag that your download is packaged with unwanted software.

  • “Download managers.” Most reputable software publisher websites will let you download programs directly from the site. Watch out for websites that make you install a download manager in order to download the software you really want. It’s common for download managers to include additional unwanted software.

Tips on protecting yourself from unwanted software

  • Get your software directly from the source. When you’re looking for a new program, look on the publisher’s website first. Software download repositories may bundle in unwanted software with legitimate downloads.

  • Avoid clicking on pop-ups or banner ads that warn you of slow performance on your computer. This is often a ruse to lead you to websites that host unwanted software.

  • Make sure everything is up-to-date. To best protect yourself, repeatedly update your browser and operating systems; older systems are more susceptible to being infected by malware. Be sure to check for computer and browser updates in computer settings. Ads claiming that your computer software is out-of-date are likely to lead you to more unwanted software.

  • Routinely scan your computer. Use antivirus software to regularly scan your computer for programs that you don’t recognize.

  • Pay attention when installing new software. When downloading programs and extensions, pay attention to the fine print. In particular, be on the lookout for pre-checked boxes that offer to install things like toolbars or other software in addition to the software you were looking for.

  • Heed your browser’s warnings. Most major Web browsers now have functionality built-in that will warn you when you are about to enter an unsafe website. Chances are that if your browser is telling you to not visit a certain website or download a particular program, you’re better off steering clear.

Here are a few examples of warnings from the most popular browsers:


Google
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Firefox
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Safari
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What to do if you suspect you’ve already installed unwanted software

Despite our best efforts, it’s still possible to inadvertently install unwanted software. Once it happens, there are several steps you can take:

  • Ensure that the latest versions of your browser and operating system are installed. The best way to defend yourself against unwanted software is to ensure that your Internet browser (Safari, Firefox, Chrome, Edge, etc.) and operating system (Windows, OSX, Linux, etc.) are up-to-date.

  • Run a security scan using a reputable antivirus removal tool. While this software isn’t perfect, an antivirus tool can help detect and remove unwanted software. If you suspect you have unwanted software on your computer, make sure your antivirus tool is up-to-date and then run a full scan. The antivirus may help to detect and remove such software.

  • Check your browser extensions. Unwanted software may be installed as an extension on your browser. You can review extensions and disable suspicious-looking ones by checking your browser’s settings page. Click here for instructions on how to do so for several popular browsers.

  • If all else fails, format and reinstall. In extreme cases, unwanted software may be so persistent that it disables operating systems or browser updates and resists antivirus removal. If it comes to that, it may become necessary to format your hard drive and reinstall your operating system and Internet browser. Before you do this however, be sure to create backups of important files (like photos, videos, and documents). WARNING: This may be a time-consuming process and beyond the skill of some users. If you don’t feel comfortable doing so, you may need to look for outside help from your local electronics store or computer manufacturer.