More than 12,300 websites in the business category were used to launch cyberattacks or deliver malware in 2017, making company sites riskier than gambling and shopping sites. Attackers are abusing people's trust in popular sites to launch consistent and effective malware campaigns.

Forty-two percent of the top 100,000 websites ranked by Alexa are considered "risky," according to Menlo Security's State of the Web 2017. Researchers determined a website's risk based on three criteria: use of vulnerable software, history of distributing malware or launching attacks, and the occurrence of a security breach within the 12 previous months.

A site was deemed risky if it met any one of these criteria. The largest category of risk was news and media sites, 49% of which met a risk factor, followed by entertainment and arts (45%), travel (41%), personal sites and blogs (40%), society (39%), and business and economy (39%), which includes company, association, industry group, financial data and serivces, and hosted business application sites.

Business and economy sites hosted more phishing sites, ran more vulnerable software, and experienced more security incidents than any other category in 2017, researchers found. The category was hit with 23,819 incidents in 2017; the next-highest was society sites at 12,669.

Background websites: Who are you talking to?

Menlo CTO Kowsik Guruswamy explains the risk of "background radiation," which stems from the idea that much of cybercriminals' damage happens behind the scenes. Each time someone visits a website, it contacts an average of 25 background sites for different demands: grabbing ads from an ad delivery network, for example, or videos from a content delivery server.

Any of these third-party sites could be compromised and pose risk to users. Most malware prevention tools, from antivirus products to behavioral modeling systems, are designed to focus on the intended domain and often don't pick up on calls to background sites.

A major website like Bloomberg might have an IT team to update servers, Guruswamy says. However, when end users visit and are presented with videos and ads, the activity comes from other networks and may not necessarily be safe. The same applies to all major websites.

As software ages, risks grow

Many of today's websites are participating in browsing sessions, and actively servicing ads, on software riddled with vulnerabilities, Guruswamy says.

"You have this really, really old software that's full of holes that haven't been patched and are waiting to be exploited," he explains, pointing to the Equifax breach as an example of what threat actors can do if a website is running unpatched software.

Menlo analysts passively fingerprinted website software for both primary and background sites, and coordinated the documented vulnerabilities for each one. They found more than 51,000 business and economy websites are running vulnerable software.

The software supporting company websites is often old enough to have been compromised several times over the past few years. More than 32,000 websites analyzed run on Microsoft Internet Information Services (IIS) 7.5, which was released in 2009. Many sites use software that is no longer fully supported; for example, Microsoft's IIS 5 Web server, which was released in 2000 and stopped receiving mainstream support in 2005.

Tactics for tricking users

Most high-profile breaches start with a phishing or spearphishing attack. In 2017, 4,600 phishing sites used legitimate hosting services. It's easier to create a subdomain on a real hosting service than hack a popular site or set up a brand-new domain, Guruswamy says.

Companies usually whitelist legitimate domains, which give them a false sense of security while covering for a phishing website. Researchers found 15 phishing sites hosted on the world's ten most popular domains. While no evidence indicated anyone was successfully breached from any of these subdomains, it's worth noting hackers are embracing hosting services.

Guruswamy calls it "trust hacking" and says many threat actors leverage websites like DocuSign or Dropbox so when targets receive emails to open documents, they don't think it's malicious.

Typosquatting is another common way of sending users to malicious websites. Attackers set up fake domains with intentional misspellings so people accidentally access them if they mistype a website in the browser. "Wellforgo.com," "Yaoo.com," and "Yotuube.com" are examples.

"It's an attack vector that's been around for a while but now bad actors are taking the time to actively get it categorized as a good site," he explains. In the 30-day period Menlo tracked users' web activity, traffic to 78 bad sites had been misspelled to trick people trying to visit the top 1,000 domains on Alexa.