For the first time in years, enterprises have more reason to be concerned about cybercriminals exploiting flaws in Microsoft software than in Adobe Flash.
Recorded Future recently analyzed code repositories, the Dark Web, underground forums, and other sources to identify the vulnerabilities that cybercriminals exploited most commonly in 2017.
The exercise revealed a marked shift in attacker preference from Adobe to Microsoft product exploits: in contrast to previous years where Adobe Flash flaws dominated Recorded Future's list of the 10 most commonly exploited vulnerabilities, seven of the top 10 in 2017 were Microsoft vulnerabilities.
By way of comparison, in 2016, six of the top 10 software flaws that cybercriminals most commonly exploited in phishing attacks and in exploit kits were in Adobe Flash. In 2015, Recorded Future found Adobe Flash accounting for eight of the top 10 vulnerabilities used by exploit kits.
The declining interest around Adobe Flash vulnerabilities appears tied to a broader decline in overall exploit kit activity, according to Recorded Future. The security vendor's analysis uncovered a 62% decline in exploit kit development in 2017, compared to 2016. Only a handful of exploit kits, such as AKBuilder, Terror, and Disdain saw any significant activity last year, Recorded Future noted.
One reason for the decreasing exploit kit activity is that Internet users are using more secure browsers these days. The massive interest around cryptocurrency mining and a trend towards more targeted attacks may also explain the dwindling interest in the use of exploit kits in attacks, Recorded Future said.
Meanwhile, topping the list of most exploited flaws in 2017 was a vulnerability disclosed in April 2017 in multiple versions of Microsoft Office (CVE-2017-0199) that gives remote attackers a way to execute arbitrary code on vulnerable systems. Multiple malware tools including some of the most prolific ones last year such as Cerber, Dridex, FinFisher, and Latenbot, exploited the vulnerability.
CVE-2016-0189, a flaw in Microsoft's Internet Explorer, ranked second because it was used in a dozen exploit kits including RIG, one of the most prolific exploits kit currently available and in others such as the Sundown, Neutrino, and Terror exploit kits.
Unsurprisingly, the vulnerabilities that attackers tended to exploit most frequently last year tended to be the ones with a high severity rating. Five of the vulnerabilities in Recorded Future's Top 10 list for 2017 had severity scores of 9.3 or higher, while four had CVSS score of 7.6.
The only exception was CVE-2017-0022, a Microsoft Windows flaw with a severity score of just 4.3 that ranked third in Recorded Future's list because two prolific exploit kits — Neutrino and Astrum — used it.
"Readers should use this report to understand some of the more obvious targets of exploitation," says Scott Donnelly, vice president of technical solutions at Recorded Future.
Generally, cybercriminals tend to go after the largest pool of targets. So products with a large user base usually end up being disproportionately represented in Recorded Future's list.
But sometimes, the CVSS score that is assigned to a security flaw may not correlate exactly with its severity in the wild. "For instance, CVE-2017-0022 had a CVSS score of 4.3, yet tops our chart due to adoption by a major exploit kit," he says. "[So], key takeaways include the suggestion to assess the currently level of exploitation of a vulnerability when deciding on patch/remediation prioritization."
Bill Lummis, technical program manager at vulnerability disclosure management provider HackerOne, says Flash Player's ubiquity was what made it such a popular target for the past several years. But with Adobe's decision to kill Flash, attackers are moving to other technologies.
"The report shows that you can't be narrowly focusing on just one exploit or just one attack vector," Lummis says.
Security administrators need to focus on improving their patch management processes for the software their users actually need and removing the software they don’t require. "Crimeware groups aren't going to pick up their ball and go home just because one piece of software becomes harder to attack," Lummis says.
"So it's important to think of the issue in terms of security best practices, rather than focusing too narrowly on specific avenues of exploitation," he says.
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