Figures from Trustwave show there has been a steady decline in exploit kit activity over the past year. Exploit kits were once one of the biggest cybersecurity threats. In late 2015 and early 2016 exploit kits were being extensively used to spread ransomware and malware. Now exploit kit activity has virtually dropped to nothing.
Exploit kits are toolkits that are loaded onto malicious or hijacked websites that probe for vulnerabilities in browsers and plugins such as Adobe Flash Player and Java. When a new zero-day vulnerability was discovered, it would rapidly be added to exploit kits and used to silently download ransomware and malware onto web visitors’ computers. Any individuals that had failed to keep their browsers and plugins up to date would be at risk of being infected. All that would be required was make them – or fool them- into visiting a malicious website.
Links were sent via spam email, malvertising was used to redirect web visitors and websites were hacked and hijacked. However, the effort required to develop exploits for vulnerabilities and host exploit kits was considerable. The potential rewards made the effort more than worthwhile.
Exploit kits such as Angler, Magnitude and Neutrino no longer pose such a big threat. The actors behind the Angler exploit kit, which was used to spread Locky ransomware in early 2016, were arrested. Law enforcement agencies across the world have also targeted gangs running these exploit kits. Today, exploit kit activity has not stopped entirely, but it is nowhere near the level seen in the first half of 2016.
While this is certainly good news, it does not mean that the threat level has reduced. Ransomware and malware are still major threats, all that has happened is cybercriminals have changed tactics for distributing the malicious programs. Exploit kits are not dead and buried. There has just been a lull in activity. New exploit kits are undoubtedly being developed. For the time being, exploit kit activity remains at a low level.
Now, the biggest threat comes from malicious spam email messages. Locky and other ransomware variants are now almost exclusively spread via spam email messages. Cybercriminals are also developing more sophisticated methods to bypass security controls, trick end users into opening infected email attachments, and improve infection rates.
Much greater effort is now being put into developing convincing phishing and spear phishing emails, while spam emails are combined with a wide range of social engineering tricks to get end users to open infected email attachments. End users are more knowledgeable and know not to click on suspicious email attachments such as executable files; however, malicious Word documents are another matter. Office documents are now extensively used to fool end users into installing malware.
With cybercriminals now favoring spam and phishing emails to spread malware and ransomware, businesses need to ensure their spam defenses are up to scratch. Employees should continue to be trained on cybersecurity, the latest email threats should be communicated to staff and advanced spam filters should be deployed to prevent messages from being delivered to end users.