Top 10 Routinely Exploited Common Vulnerabilities & Exposures

Health-ISAC Vulnerability Bulletin

Date:  May 14, 2020 

TLP:WHITE 

Event: Top 10 Routinely Exploited Common Vulnerabilities & Exposures (CVEs) 
 

Summary: 

This alert provides details on vulnerabilities that are routinely being exploited by nation state cyber actors.  Organizations can greatly reduce the risk of these foreign threats by applying patches. 

On May 13, 2020, the Cybersecurity and Infrastructure Security Agency (CISA), the Federal Bureau of Investigation (FBI), and the broader U.S. Government issued an alert (AA20-133A) to advise IT security professionals at public and private sector organizations to place an increased priority on patching the most commonly known vulnerabilities exploited by sophisticated foreign cyber actors. 

Analysis: 

Foreign cyber actors continue to exploit publicly known—and often dated—software vulnerabilities against broad target sets, including public and private sector organizations, including the healthcare sector. Exploitation of these vulnerabilities often requires fewer resources as compared with zero-day exploits for which no patches are available. 

Health-ISAC member organizations could reduce the threats from some sophisticated nation state actors through an increased effort to patch systems and implement programs to keep system patching up to date. A concerted campaign to patch these vulnerabilities would introduce friction into adversaries’ operational tradecraft and force them to develop or acquire exploits that are more costly and less widely effective. A concerted patching campaign would also bolster network security by focusing scarce defensive resources on the observed activities of nation state adversaries. 

Technical Details:   

Most Exploited Vulnerabilities during 2016-2019 

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 nation 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 nation 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. 

Most Exploited Vulnerabilities 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 expedited deployment of Microsoft O365 may have led to oversights in security configurations 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.

Mitigations: 

This Alert provides mitigations for each of the top vulnerabilities identified above. In addition to the mitigations listed below, CISA, FBI, and the broader U.S. Government recommend that organizations transition away from any end-of-life software. 

Members can report suspicious / adversarial activity to the H-ISAC Threat Operations Center (TOC) and H-ISAC will aggregate the information in an anonymous report to share to the FBI on behalf of the healthcare sector. 

Mitigations for the Most Exploited Vulnerabilities 2016–2019

Note: The lists of associated malware corresponding to each CVE below is not meant to be exhaustive but instead is intended to identify a malware family commonly associated with exploiting the CVE.  

CVE-2017-0143 

• – Vulnerable Products: Microsoft Windows Vista SP2; Windows Server 2008 SP2 and R2 SP1; Windows 7 SP1; Windows 8.1; Windows Server 2012 Gold and R2; Windows RT 8.1; and Windows 10 Gold, 1511, and 1607; and Windows Server 2016 
• – Associated Malware: Multiple using the EternalSynergy and EternalBlue Exploit Kit 
• – Mitigation: Update affected Microsoft products with the latest security patches 
• – More Detail: https://nvd.nist.gov/vuln/detail/CVE-2017-0143 

CVE-2018-4878 

• – Vulnerable Products: Adobe Flash Player before 28.0.0.161 
• – Associated Malware: DOGCALL 
• – Mitigation: Update Adobe Flash Player installation to the latest version 
• – More Detail: https://nvd.nist.gov/vuln/detail/CVE-2018-4878 
• – IOCs: https://www.us-cert.gov/ncas/analysis-reports/ar20-133d 

CVE-2017-8759 

• – Vulnerable Products: Microsoft .NET Framework 2.0, 3.5, 3.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2 and 4.7 
• – Associated Malware: FINSPY, FinFisher, WingBird 
• – Mitigation: Update affected Microsoft products with the latest security patches 
• – More Detail: https://nvd.nist.gov/vuln/detail/CVE-2017-8759 
• – IOCs: https://www.us-cert.gov/ncas/analysis-reports/ar20-133f 

CVE-2015-1641 

• – Vulnerable Products: Microsoft Word 2007 SP3, Office 2010 SP2, Word 2010 SP2, Word 2013 SP1, Word 2013 RT SP1, Word for Mac 2011, Office Compatibility Pack SP3, Word Automation Services on SharePoint Server 2010 SP2 and 2013 SP1, and Office Web Apps Server 2010 SP2 and 2013 SP1 
• – Associated Malware: Toshliph, UWarrior 
• – Mitigation: Update affected Microsoft products with the latest security patches 
• – More Detail: https://nvd.nist.gov/vuln/detail/CVE-2015-1641 
• – IOCs: https://www.us-cert.gov/ncas/analysis-reports/ar20-133m 

CVE-2018-7600 

• – Vulnerable Products: Drupal before 7.58, 8.x before 8.3.9, 8.4.x before 8.4.6, and 8.5.x before 8.5.1 
• – Associated Malware: Kitty 
• – Mitigation: Upgrade to the most recent version of Drupal 7 or 8 core. 
• – More Detail: https://nvd.nist.gov/vuln/detail/CVE-2018-7600 

Mitigations for Most Exploited Vulnerabilities in 2020 

CVE-2019-19781 

• – Vulnerable Products: Citrix Application Delivery Controller, Citrix Gateway, and Citrix SDWAN WANOP 
• – Mitigation: Update affected Citrix devices with the latest security patches 
• – More Detail: 
•    ~ https://www.us-cert.gov/ncas/alerts/aa20-020a  
•    ~ https://www.us-cert.gov/ncas/alerts/aa20-031a  
•    ~ https://www.fireeye.com/blog/products-and-services/2020/01/fireeye-and-citrix-tool-scans-for-iocs-related-to-vulnerability.html  
•    ~ https://nvd.nist.gov/vuln/detail/CVE-2019-19781  
•    ~ https://www.microsoft.com/security/blog/2020/04/28/ransomware-groups-continue-to-target-healthcare-critical-services-heres-how-to-reduce-risk/  

Organizational Cybersecurity Weaknesses 

• – Vulnerable Products: Systems, networks, and data 
• – Mitigation: Follow cybersecurity best practices 
• – More Detail: https://www.cisa.gov/cyber-essentials 

CISA Online Resources 

The Patch Factory: CISA infographic depicting the global infrastructure for managing vulnerabilities. 

https://www.us-cert.gov/sites/default/files/publications/patch_factory_S508C.pdf

CISA Alert: (AA20-120A) Microsoft Office 365 Security Recommendations: recommendations for organizations to review and ensure their O365 environment is configured to protect, detect, and respond against would-be attackers. 
https://cve.mitre.org/cve/

CISA’s Cyber Essentials: a guide for leaders of small businesses as well as leaders of small and local government agencies to develop an actionable understanding of where to start implementing organizational cybersecurity practices. 
https://www.us-cert.gov/ncas/alerts/TA15-119A

Recognition & References: 

• – Health Industry Cybersecurity Practices (HICP): Managing Threats and Protecting Patients publication  

https://healthsectorcouncil.org/hhs-and-hscc-release-voluntary-cybersecurity-practices-for-the-health-industry/ 

• – Cybersecurity Vulnerabilities and Exposures (CVE) list 

https://cve.mitre.org/cve/ 

• – CISA Alert (TA15-119A) Top 30 Targeted High Risk Vulnerabilities  

https://www.us-cert.gov/ncas/alerts/TA15-119A 

• – Recorded Future. 2019 Vulnerability Report: Cybercriminals Continue to Market Microsoft Products  

https://www.recordedfuture.com/top-vulnerabilities-2019/