VPN Attacks: A Rising Threat for Remote Work in the COVID-19 Era

Attacks against virtual private network (VPN) products from Fortinet and Pulse Secure have surged dramatically in the first quarter of 2021. A recent report released by Nuspire, a leading managed security services provider (MSSP), revealed that threat actors managed to gain an initial position in the network using a compromised VPN password, resulting in huge data loss and disruption to several services.

 
These incidents reported in the investigation indicate the failure to provide an additional layer of security to VPN accounts, along with the malicious actors taking advantage of unpatched vulnerabilities disclosed earlier
Sourced from its 90 billion traffic logs, the “2021 Q1 Threat Landscape Report” outlined the following concerns.

• Attacks against Fortinet’s SSL-VPN jumped to 1,916% in the first quarter of 2021 and a 1,527% spike in the attacks against Pulse Secure VPN.

• To launch cyberattacks, threat actors tried abusing flaws that were disclosed earlier. Two highly targeted flaws included a path reversal vulnerability (CVE-2018-13379) affecting Fortinet VPN and a file distribution vulnerability (CVE-2019-11510) in Pulse Secure Connect VPN.

Having flaws in their respective products, both the vendors were issued patches a long time back. Even the security analysts have been warning them for some time about the high adversary concern in the vulnerabilities. In fact, in January 2020, Tenable had warned of threat actors leveraging the flaw detected in Pulse Connect Secure to distribute the ransomware strain named Sodinokibi. Later in April, the NSA, FBI, and the Department of Homeland Security's Cybersecurity and Infrastructure Security Agency (CISA) detected Russia's Foreign Intelligence Service (SVR) as targeting the Fortinet and Pulse Secure VPN flaws in attacks against US and allied networks.

“2020 was the era of remote work and as the workforce adjusted, information technology professionals scrambled to support this level of remote activity by enabling a wide variety of remote connectivity methods,” said J.R. Cunningham, Nuspire Chief Security Officer. “This added multiple new attack vectors that enabled threat actors to prey on organizations, which is what we started to see in Q1 and are continuing to see today.”

Recently, the cyber forensic team of FireEye’s Mandiant discovered four new malware tools that weaponized Pulse Secure vulnerabilities. Threat actor groups- UNC2630 and UNC2717- used tools called, Bloodmine, Bloodbank, Cleanpulse, and Rapidpulse to establish tenacity on devices connected to Pulse Secure VPNs. The attackers used these tools to launch attacks against defense, government, technology, transport, and financial entities in the U.S. and Europe.

In the first week of June, another incident of malicious attacks via a SonicWall VPN flaw was also reported. Malicious actors exploited an old vulnerability (CVE-2019-7481) in the VPN to compromise older SonicWall SRA 4600 VPN devices.

These reported attacks on VPNs indicate that threat actors can find many ways to exploit and monetize a vulnerable VPN. Further, the slow response shown in patching the vulnerabilities allows adversaries to launch attacks against vulnerable endpoints. Once they get in, navigating to exfiltrate information and deploying malware becomes easy.
Jerry Nguyen, director of threat intelligence and rapid response at Nuspire, has stated that the large spike in activity targeting VPN devices in Q1 2021 had to do with organizations not patching these vulnerabilities despite previous warnings.
"The US CIRT released a number of reminder alerts that attackers were looking at these VPNs and people should patch," Nguyen says. "The biggest thing we are seeing with VPNs [is that] everyone is looking at the endpoint and not the perimeter when they need to look at both."

Declining Trend In Other Malicious Activity
Ironically, the VPN attacks increased amid an overall decrease in malware, botnet, and other types of exploit activity. Nuspire's analysis of threat data from the first quarter of 2021 indicates a declining trend in malware activity by more than 54% in comparison to Q4 2020. There’s a significant drop in vulnerability exploit activity, other than that targeting VPNs, nearly 22% compared with the previous quarter and while botnet activity declined by some 11%.

According to Nguyen, it is the law enforcement's takedown of the massive Emotet operation in January that relatively led to a sharp drop in malware, exploit, and botnet activity.

"Emotet has consistently been one of the top trending malwares in our threat reports, and it created a vacuum when shut down," Nguyen says.

However, the present trend is likely temporary and it can once again go upward in the last quarter.
"I would expect another malware family, such as TrickBot, potentially to begin to trend more or a new malware variant take over," Nguyen says. "Threat actors will not just stop distributing malware. They will adapt and move on to something new."
Josh Smith, the security analyst at Nuspire, has suggested enterprise organizations pay close attention to remote access security involving VPNs and Microsoft's Remote Desktop Protocol — another popular target for attackers. Both technologies offer malicious actors wide access to a network for deploying ransomware. Organizations should monitor their technology asset and ensure applying security patches without any delay. Implementing multifactor authentication (MFA) is also vital, he says.
"End users may find it frustrating to have to enter MFA codes, but if credentials are leaked that allow access to a remote service, MFA can be the difference between a successful breach or stopping a threat actor’s access," said Josh Smith.

How to Prevent Attacks
The situation due to the global pandemic COVID-19 led to the advent of an era where organizations are shifting to remote working culture and moving their infrastructure, networks, and applications to the cloud. However, loose security ends make everything accessible to users and threat actors. Cybercriminals have become more active in this era and involved in conducting widespread scanning and exploitation against systems. Thus, more unexpected trends can be observed in 2021. VPN, a vital tool for remote working, remains one of the biggest targets to breach security endpoint systems. Therefore, organizations should always be watchful of potential attacks and apply patches immediately after they are released by vendors.

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