Security Experts:

US Gov Warning: VPN, Network Perimeter Product Flaws Under Constant Attack

The U.S. government and its allies are pleading with defenders to pay attention to gaping holes in perimeter-type devices, warning that advanced threat actors are feasting on known security defects in VPN appliances, network product gateways and enterprise cloud applications.

In a joint advisory published Wednesday, cybersecurity response agencies from the U.S., the U.K., and Australia called special attention to flaws in network perimeter tech from Citrix, Fortinet, Pulse, F5 Networks and MobileIron.

The agencies listed 30 distinct security vulnerabilities (categorized by CVEs) that have been “routinely exploited” over the last two years to plant malware on public and private sector organizations around the world.

According to the data, it’s clear that the pandemic-induced shift to remote work has introduced low hanging fruit for attackers to exploit. In 2021, four of the most targeted vulnerabilities affected remote work, VPNs, or cloud-based technologies. 

“Many VPN gateway devices remained unpatched during 2020. The rapid shift and increased use of remote work options, such as virtual private networks (VPNs) and cloud-based environments, likely placed additional burden on cyber defenders struggling to maintain and keep pace with routine software patching,” the agencies said.

The list of the most commonly exploited flaws observed in 2021 includes some of the most widely deployed enterprise products:

  • Microsoft Exchange: CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065 
  • Pulse Secure: CVE-2021-22893, CVE-2021-22894, CVE-2021-22899, and CVE-2021-22900
  • Accellion: CVE-2021-27101, CVE-2021-27102, CVE-2021-27103, CVE-2021-27104
  • VMware: CVE-2021-21985
  • Fortinet: CVE-2018-13379, CVE-2020-12812, and CVE-2019-5591 

Anti-malware researchers confirm that exploits for these vulnerabilities have been used as initial entry points for ransomware attacks and nation-state APT cyberespionage campaigns.

[ Read: Why Are Users Ignoring Multi-Factor Authentication? ]

The agencies also published a separate list of the CVEs that were exploited the most in 2020, right in the midst of the global shift to deploying WFH remote work technologies:
  • CVE-2019-19781 -- Citrix Netscaler arbitrary code execution
  • CVE 2019-11510 -- Pulse arbitrary file reading 
  • CVE 2018-13379 -- Fortinet path traversal 
  • CVE 2020-5902 -- F5- Big IP remote code execution (RCE) 
  • CVE 2020-15505 -- MobileIron remote code execution
  • CVE-2017-11882 - Microsoft remote code execution
  • CVE-2019-11580 -- Atlassian remote code execution
  • CVE-2018-7600 -- Drupal remote code execution
  • CVE 2019-18935 -- Telerik remote code execution
  • CVE-2019-0604 -- Microsoft remote code execution
  • CVE-2020-0787 -- Microsoft elevation of privilege 
  • CVE-2020-1472 -- Netlogon elevation of privilege 

In the joint advisory (PDF), the agencies said public and private organizations worldwide should assume their networks are already compromised if these vulnerabilities haven’t yet been addressed.

“Organizations that have not remediated these vulnerabilities should investigate for the presence of IOCs and, if compromised, initiate incident response and recovery plans,” the agencies warned.

The advisory contains technical details of every vulnerability, mitigation guidance and indicators of compromise (IOCs) to help organizations manage these risks.

Related: Researchers Raise Alarm for F5 BIG-IP Malware Attacks

Related: Microsoft: Multiple Exchange Server Zero-Days Under Attack

Related: NSA: Russian Hackers Exploiting VPN Vulnerabilities - Patch Now

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Ryan Naraine is Editor-at-Large at SecurityWeek and host of the popular Security Conversations podcast series. Ryan is a veteran cybersecurity strategist who has built security engagement programs at major global brands, including Intel Corp., Bishop Fox and GReAT. He is a co-founder of Threatpost and the global SAS conference series. Ryan's past career as a security journalist included bylines at major technology publications including Ziff Davis eWEEK, CBS Interactive's ZDNet, PCMag and PC World. Ryan is a director of the Security Tinkerers non-profit, an advisor to early-stage entrepreneurs, and a regular speaker at security conferences around the world. Follow Ryan on Twitter @ryanaraine.