Security firm Symantec claims that exploit kits spread malware to users only at half the rate that email does, with one of every nine email users encountering malware in the first half of 2017.
The claim was made in the company's latest Internet Security Threat Report, with this one concentrating on email threats.
The report did not specify how many individuals were surveyed to arrive at this conclusion or the geographical regions covered, though presumably the data used was from Symantec's operations worldwide.
Given the descriptions within the report, the users surveyed appear to be overwhelmingly Windows users.
{loadposition sam08}Other findings were that business email compromise scams targeted about 8000 businesses each month, with an organisation that was targeted receiving an average of 5.2 such scam emails in a given month.
Symantec analyst Ben Nahorney said that 54% of email received by those surveyed was spam and this was expected to increase in the second half of 2017.
An organisation that did not use spam filters had to effectively employ two people to manage the spam that every 100 employees received, Nahorney added.
The report claimed that email was the most frequently used delivery mechanism for malware.
"According to research we conducted across different threat vectors, no other distribution channel comes close: not compromised websites containing exploit kits, not network file sharing technologies like SMB, not malicious advertising campaigns that entice users to click on banner ads," Nahorney said.
"In fact, a user is almost twice as likely to encounter malware through email than come across a malicious website."
In terms of industry segments targeted, 23.8% of users in the wholesale trade industry were targeted, with mining (22.6%) and non-classifiable firms (20.3%) making up the top three.
The top three malicious email subject lines were to do with a bill or invoice, delivery of a package and scanned documents.
The report said that the primary method for distribution of malicious emails was through spambots, with Necurs being the main spambot responsible, even though it went missing in the first three months of 2017.
Other spambots which were prominent in the period surveyed were BlankSlate (email subject and body empty), Fioesrat (used for attacking PHP servers), Silentbrute (usually sends an Office document), Pandex (also used to distribute ransomware), Oliner, Sarvdap, Emotet and Walkedac.
In the case of business email compromise, the most common subject line was to do with payment. However there were also scams which aimed to obtain company documents, such as those to do with taxation.
"One of the more interesting developments in the BEC sphere are attacks where the scammers are attempting to obtain other assets, as opposed to directly stealing money," Nahorney said. "In one BEC campaign early in 2017 the scammers appeared to be focused on obtaining the employee’s American tax form, the W2, from the targeted organisations."
The report said that while the spam rate had fallen, it continued to make up more than half of the email received by those surveyed.
"Based on median salary data from the US Census Bureau, spending 10 minutes managing spam adds up to US$4.51 per employee each day. That’s US$1177.42 spent annually for one employee to filter spam," Nahorney said.
"For every 100 employees a business has, this comes out to US$117,741.67 per year. That’s the equivalent of having two full-time employees dedicated to simply managing spam – a far less trivial figure."
Graphics: courtesy Symantec