The Cybersecurity and Infrastructure Security Agency (CISA), the Federal Bureau of Investigation (FBI), and the broader U.S. Government released a list today of the top 10 vulnerabilities most commonly exploited by foreign cyber actors.
The exploitation of these vulnerabilities often requires fewer resources compared to zero-day exploits for which no patches are available.
Top 10 Most Exploited Vulnerabilities 2016–2019
Source: us-cert.gov
U.S. Government reporting has identified the top 10 most exploited vulnerabilities by state, nonstate, and unattributed cyber actors from 2016 to 2019 as follows: CVE-2017-11882, CVE-2017-0199, CVE-2017-5638, CVE-2012-0158, CVE-2019-0604, CVE-2017-0143, CVE-2018-4878, CVE-2017-8759, CVE-2015-1641, and CVE-2018-7600.
- According to U.S. Government technical analysis, malicious cyber actors most often exploited vulnerabilities in Microsoft’s Object Linking and Embedding (OLE) technology. OLE allows documents to contain embedded content from other applications such as spreadsheets. After OLE the second-most-reported vulnerable technology was a widespread Web framework known as Apache Struts.
- Of the top 10, the three vulnerabilities used most frequently across state-sponsored cyber actors from China, Iran, North Korea, and Russia are CVE-2017-11882, CVE-2017-0199, and CVE-2012-0158. All three of these vulnerabilities are related to Microsoft’s OLE technology.
- As of December 2019, Chinese state cyber actors were frequently exploiting the same vulnerability—CVE-2012-0158—that the U.S. Government publicly assessed in 2015 was the most used in their cyber operations. This trend suggests that organizations have not yet widely implemented patches for this vulnerability and that Chinese state cyber actors may continue to incorporate dated flaws into their operational tradecraft as long as they remain effective.
- Deploying patches often requires IT, security professionals, to balance the need to mitigate vulnerabilities with the need for keeping systems running and ensuring installed patches are compatible with other software. This can require a significant investment of effort, particularly when mitigating multiple flaws at the same time.
- A U.S. industry study released in early 2019 similarly discovered that the flaws malicious cyber actors exploited the most consistently were in Microsoft and Adobe Flash products, probably because of the widespread use of these technologies. Four of the industry study’s top 10 most exploited flaws also appear on this Alert’s list, highlighting how U.S. Government and private-sector data sources may complement each other to enhance security.
Vulnerabilities Exploited in 2020
In addition to the top 10 vulnerabilities from 2016 to 2019 listed above, the U.S. Government has reported that the following vulnerabilities are being routinely exploited by sophisticated foreign cyber actors in 2020:
- Malicious cyber actors are increasingly targeting unpatched Virtual Private Network vulnerabilities.
- An arbitrary code execution vulnerability in Citrix VPN appliances, known as CVE-2019-19781, has been detected in exploits in the wild.
- An arbitrary file reading vulnerability in Pulse Secure VPN servers, known as CVE-2019-11510, continues to be an attractive target for malicious actors.
- March 2020 brought an abrupt shift to work-from-home that necessitated, for many organizations, rapid deployment of cloud collaboration services, such as Microsoft Office 365 (O365). Malicious cyber actors are targeting organizations whose hasty deployment of Microsoft O365 may have led to oversights in security configurations and vulnerable to attack.
- Cybersecurity weaknesses—such as poor employee education on social engineering attacks and a lack of system recovery and contingency plans—have continued to make organizations susceptible to ransomware attacks in 2020.
Here’s a comment from Satnam Narang, Staff Research Engineer at Tenable providing an analysis of a trend seen within these top 10 vulnerabilities.
CISA’s list of the top 10 routinely exploited vulnerabilities from 2016 through 2019 primarily consists of flaws in Microsoft products, particularly in Microsoft Office. This comes as no surprise as cybercriminals go after low hanging fruit, which is often ubiquitous software with known but unpatched vulnerabilities. Many of the bad actors leverage flaws in Office when distributing spear-phishing emails to their intended targets. These emails are tailored to their victim, using a lure designed to capture their interest in order to convince them to open the malicious attachment.
This list is indicative of a trend we see time and time again: Cybercriminals prefer to leverage known but unpatched vulnerabilities. Finding or acquiring zero-day vulnerabilities is a costly endeavor, so leveraging unpatched flaws with publicly available exploit code gets them to their end goal in the fastest and cheapest way possible.
Vulnerabilities in Virtual Private Network (VPN) solutions are another area that has seen an increase in activity going back to 2019 when exploiting code for several notable VPNs became publicly available. We anticipate that many of these flaws will continue to be leveraged by bad actors of all kinds because as they say if it ain’t broke, don’t fix it.
This list is a solid reminder of the importance of basic cyber hygiene and systems maintenance. Knowing which vulnerabilities are being actively exploited by bad actors and prioritizing their remediation is one of the most effective ways to reduce risk.
