Eight of the top ten most exploited vulnerabilities in 2018 affected Microsoft products. Only one -- but the second most exploited -- was an Adobe vulnerability. The last one, ranking at the ninth most exploited vulnerability of 2018, was an Android vulnerability.
These details come from Recorded Future's Cyber Threat Analysis of vulnerabilities exploited throughout 2018. The intelligence comes from thousands of different resources, including code repositories, deep web forum postings and dark web onion sites. The purpose is to provide a missing link in today's risk analysis. Vulnerability databases provide information about vulnerabilities, but do not disclose whether or to what extent each one is being actively exploited.
It is worth noting that some of the best-known vulnerabilities, such as those exploited by EternalBlue and Specter/Meltdown, don't make the list. This is because they tended to be used by a limited number of nation states rather than a large number of criminals. "The ETERNALBLUE exploit (which used MS17-010)," notes the report, "while often mentioned, was not used by the criminal underground or offered for sale as a part of other exploit kits. Spectre, while noted in a few phishing attacks, was not also heavily utilized by under criminals."
By knowing which threats are most active, security teams can prioritize which systems most urgently need patching or other mitigating actions. In a 2017 analysis of zero-day threats, RAND Corporation pointed out that vulnerabilities on average have a seven-year life-cycle. The most exploited vulnerabilities from 2018 will almost certainly still be exploited in 2019.
For example, the most exploited vulnerability in 2017 (CVE-2017-0199) was still the fifth most exploited vulnerability in 2018. The most exploited vulnerability of 2016 (CVE-2016-0189) was still the sixth most exploited in 2018, being used by five different exploit kits. And the oldest vulnerability in the list dates from 2012, and is still present in EKs today.
Recorded Future's analysis also looked at exploit kits (EKs) and remote access trojans (RATs). In both cases, the decline in new development is continuing. In 2017, there were ten new EKs. In 2018, this had dropped to five new EKs. The most-referenced EK on the dark web was Threadkit (which first emerged in 2017). Threadkit contains four of the 2018 top ten Microsoft vulnerabilities (CVE-2018-4878, CVE-2017-11882, CVE-2017-0199, and CVE-2017-8570), and was selling for $400 in December 2018. It was last updated on December 28 by mrbass, a user on a dark web forum, to include vulnerability CVE-2018-15982. This is an Adobe vulnerability too recent to make the top ten for the whole year.
The only two ransomwares highlighted in this report are Gandcrab and Hermes. Gandcrab is delivered by the Fallout and Grandsoft EKs -- which is fairly typical of consumer targeted ransomware. Recent reports have suggested that GandCrab is increasingly being targeted against businesses. Interestingly, a new report from BitDefender says that North Korean "hackers are targeting the websites of [Chinese] government departments with emails containing [GandCrab] ransomware." The attribution, however, is limited to a North Korean name in the email header -- which seems a somewhat flimsy. Hermes is being delivered via the Adobe vulnerability.
In 2017, there were 47 new RATs, but only 35 in 2018.
Allan Liska, Recorded Future's threat intelligence analyst, told SecurityWeek that the shift away from EK's is likely linked to the growth of targeted attacks. He doesn't believe, however, that this indicates a growth in sophisticated criminals over script kiddies (who traditionally bought or hired EKs). "The growth of cybercrime as a service now makes it easy for less tech-savvy criminals to launch targeted attacks." However, he added, "a second reason for the decline in EK usage is that they are getting less effective. They are primarily used in browsers, and there are fewer browser exploits available. The few EKs that remain very effective are being used more than others, simply because they still work."
Use of Adobe vulnerabilities continued its decline in 2018. In 2015 and 2016, the majority of most-used vulnerabilities were Adobe vulnerabilities -- in 2018 there was just one in the top ten. Recorded Future believes this is likely down to the impending demise of Adobe Flash in 2020 -- but note the emergence of CVE-2018-15982 at the end of 2018 and its inclusion in the Threadkit (also added to Fallout) EK in January 2019.
The report makes a few specific recommendations for security teams. Top of the list, unsurprisingly, is "Prioritize patching of all the vulnerabilities identified in this post." Most of the remaining advice is fairly standard 'good practice'; but two suggestions stand out as slightly unusual: consider using the Chrome browser; and employ an ad-blocker.
"Right now," explained Liska, "the Chrome track record is pretty good. Every browser has exploits. They are one of the most, if not the most, targeted pieces of software. What we've seen is that Chrome is quick to patch any new vulnerabilities and all versions have the auto-update feature, so they get updated relatively quickly. There aren't many unpatched versions of Chrome around, and Google has built in a number of additional protections. When vulnerabilities are found in Chrome, our research suggests that they are difficult to exploit. So, purely from a security perspective, Chrome is an excellent browser choice."
The second most frequently exploited vulnerability, the Adobe vulnerability, is primarily delivered through malvertising -- and malvertising is a perennial and largely invisible threat.
Related: The Top Vulnerabilities Exploited by Cybercriminals