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US Government Alerts of Imminent Attacks Against the Healthcare Sector by Trickbot Group

Arete Analysis

Executive Summary

Last week,  the Cybersecurity and Infrastructure Security Agency (CISA) in collaboration with the Federal Bureau of Investigation (FBI), and the Department of Health and Human Services (HHS) released the following alert: AA20-302A – Ransomware Activity Targeting the Healthcare and Public Health Sector.

The alert informs that there is credible intelligence of an increased and imminent cybercrime threat to U.S. hospitals and healthcare providers associated with the Trickbot and BazarLoader trojans that often leads to ransomware like the Ryuk and Conti ransomware. The alert also mentions the Trickbot Anchor tool set and Anchor DNS tool developed by this group.

News of these attacks against the Healthcare sector are of special concern due to the recent increase of COVID-19 cases in the US and evidence that shows ransomware attacks against the healthcare sector have been associated with persons losing their lives due to services being routed to nearby hospitals and laboratory results not being quickly delivered electronically to the providers.

Arete statistics and Intel from Arete’s Fusion Center and Open-source intelligence (OSINT) shows that this new wave of attacks since October 2020 have a slight change in TTPs and the BazarLoader malware has now been observed in systems compromised with Ryuk.

The Arete incident response (IR) practice has responded to more than ninety (90) Ryuk engagements since 2019 with more than six breach responses engagements just in the month of October 2020.

Based on Intelligence gathered from our DFIR cases, Arete’s Fusion Center had developed countermeasures deployed in the SentinelOne EDR platform to detect these threats and our Managed Detection and Response (MDR) team has been handling detections at our client’s sites.

This article is meant to share with the community Arete’s statistics and our assessment based on breach response engagements.

Statistical Data from Arete’s Metrics

The information listed below is based on Ryuk cases investigated by Arete IR since January 2019. Our IR and Data Analytics practices work together to track key data points for every ransomware engagement.  Our IR practice tracks data points on the ransomware variant and collects statis-tics based on handled engagements:

  • Since 2019, Arete has responded to Ryuk cases in some of the following sectors:

Healthcare: 19 | Professional Service: 28 | Public services: 21 | Manufacturing: 11 | Technology/Engineing/ Telecom: 6 | Critical Infrastructure: 1

  • Average duration of business downtime: 9.47 days

  • Average original ransom demand in bitcoin: 125.39 BTC

  • Average final ransom demand in bitcoin: 72.58 BTC

  • Average ransom demand paid in US dollars: $621,064.05

  • Minimum ransom demand paid in US dollars: $10,000.00

  • Maximum ransom demand paid in US dollars: $5,177,510.78

  • Remote access is the most common method of intrusion found 39.34% of the times

  • During the Ryuk dwell time this year, Arete responded to ten (10) Conti ransomware engagements

Ryuk Ransomware Overview

Since August 2018, a Russian-based cybercrime group has been operating a ransomware known as Ryuk (a customized version of Hermes commodity ransomware).

The industry saw a sudden drop of Ryuk, starting around the time that COVID-19 had its major impact in March 2020. This is also around the same time that a very similar, Conti ransomware, began to kick-off, leading many to believe that Conti was merely a rebrand of Ryuk. The data suggests though that it is possible that Conti was a failed rebrand since Arete IR has not been engaged with Conti infected clients since Ryuk attacks started again in October 2020.

Ryuk typically compromises networks through Trickbot, or Emotet then delivering Trickbot. Trickbot has recently been in the news in the cyber industry due to Microsoft’s approval via a court order to engage in disruption efforts of this botnet. With this active disruption campaign, it is possible that the sudden return and up-tick of Ryuk infections is due to the Russian cybercrime group acting in retaliation utilizing their more mature ransomware product, Ryuk, as opposed to the potentially rebranded, Conti, which could still have been in a testing phase. This is based on the sudden stop of Conti and up-rise of Ryuk in line with the disruption efforts from Microsoft.

According to Microsoft, they initially disabled sixty-two (62) of the initially identified sixty-nine (69) Trickbot servers. Almost immediately, fifty-nine (59) new servers were attempted to be added to the Trickbot infrastructure. As of October 20, 2020, fifty-eight (58) of the new servers have also been disabled leaving a total number of eight (8) known active Trickbot servers.

Ryuk Wave Crashing on US Healthcare

Of the more than ninety (90) total Ryuk ransomware engagements that Arete IR has led since May 2019, nineteen (19) of those engagements were for a client in the healthcare industry (23%).  Out of the seven (7) engagements of Ryuk ransomware that Arete IR has led since it re-emerged in October 2020, the most recent case is the only client that is in the healthcare industry (14%). This evidence shows it is not typical for Ryuk attacks to be focused primarily on the healthcare industry. This could further backup the theory that the impending Ryuk wave of attacks on the healthcare

industry could be retaliation for Microsoft’s disruption campaign against the Trickbot infrastructure that Ryuk is known for utilizing for initial intrusion.

Recommendations

  • Install an Endpoint Detection and Response (EDR) solution with the capability to halt detected processes and isolate systems on the network, based on identified conditions

  • Block: Any known attacker C2s in the firewall; A high number of SMB connection attempts from one system to others in the network over a short period of time

  • Implement: A system enforced password policy to force users into changing passwords at least every 90 days; Multifactor authentication (MFA) on RDP and VPN access

  • If not needed, eliminate vulnerable RDP ports exposed to the internet

  • Perform: Dark web monitoring periodically to verify if data from the organization is available for sell in the black market; Penetration tests • Periodically patch systems and update tools

  • Monitor: Connections to the network from suspicious locations; Downloadsuploads of files to file sharing services over non-standard hours, not commonly used in the organization, etc; Uploads of files from Domain Controllers to the internet; Network scans from uncommon servers (e.g. RDP server)

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Article

FortiBleed Campaign Linked to INC and Lynx Ransomware Operations

Researchers have linked the FortiBleed credential-harvesting campaign to the INC and Lynx ransomware-as-a-service (RaaS) operations, establishing a direct connection between large-scale FortiGate credential theft and subsequent ransomware deployment. The attribution is based on a variety of factors, including an operator observed managing negotiation panels for both ransomware groups, notable overlap between FortiBleed victim data and subsequent ransomware targets, and internal infrastructure exposing attack workflows. The campaign is estimated to have targeted more than 430,000 internet-facing FortiGate devices, resulting in administrative access to hundreds of organizations. 

What’s Notable and Unique

  • Researchers identified a shared operator actively managing negotiation panels for both the INC and Lynx ransomware groups, providing rare operational evidence linking the two RaaS operations beyond infrastructure or malware similarities. 


  • Analysis of the exposed infrastructure revealed a structured ransomware operation with dedicated roles for access acquisition, victim management, negotiations, and technical support, reflecting an organized ransomware-as-a-service (RaaS) model rather than an ad hoc criminal group. 


  • The operation reportedly integrates artificial intelligence into multiple stages of the attack lifecycle, including vulnerability research, penetration testing, attack automation, and ransomware development, demonstrating the increasing adoption of AI to enhance offensive capabilities.

Mitigations

Organizations should assume that exposed or previously compromised FortiGate credentials may be leveraged for ransomware deployment and immediately reset administrative and VPN credentials while enforcing multi-factor authentication (MFA) for all privileged access. Security teams should ensure that FortiGate appliances are fully patched, restrict management interfaces to trusted networks, and audit administrative accounts and firewall configurations for unauthorized changes. Organizations should also monitor for anomalous authentication activity, hunt for published indicators of compromise (IOCs), and review VPN and firewall logs for signs of unauthorized access. Maintaining centralized logging and a well-practiced incident response process can help detect and contain attacks before they progress to lateral movement or ransomware deployment.

Analyst Comments

The attribution of FortiBleed to the INC and Lynx ransomware operations reinforces the growing convergence between credential-harvesting campaigns and ransomware deployment, highlighting the role of initial access operations in modern RaaS ecosystems. The relationship between INC and Lynx also aligns with Arete's previous research, which identified a shared malware lineage. INC Ransom, first observed in 2023, was later leaked or sold, enabling code reuse by other threat actors. Lynx, which emerged in 2024, is widely regarded as an evolution of the INC codebase. Sinobi ransomware, identified in 2025, shares near-identical binaries and infrastructure, and approximately 99% code similarity with Lynx. Further details on the code correlation between INC, Lynx, and Sinobi are available in Arete's 2025 Annual Report.

Sources

  • Is FortiBleed Linked to INC and Lynx Ransomware?   

  • FortiBleed credential-theft campaign linked to Lynx ransomware   

  • FortiBleed Unmasked: A Joint Operation by Lynx and INC Ransomware Groups   

  • FortiBleed Credential Theft Campaign Attributed to INC and Lynx Ransomware Groups  

Article

Ransomware Trends & Data Insights: June 2026

Although Akira was once again the most active ransomware threat in June, activity remained relatively distributed among multiple threat groups, with 17 unique threat groups observed throughout the month. Along with Akira, Qilin and INC Ransom remained active and were among the top five most active threat groups observed in June. Several new threat actors also emerged during the month, including KryBit, Settra, and Icarus.

Figure 1. Activity from the top 5 threat groups in June 2026

Throughout the month, analysts at Arete identified several trends behind the threat actors perpetrating cybercrime activities:

  • In June, a threat actor calling themselves Icarus compromised and exfiltrated data from customers of the market intelligence platform Klue. Klue later confirmed the security incident, which involved attackers stealing OAuth tokens used to connect to customers' Salesforce environments, and reported that the threat actor was deleting the data stolen from affected Klue customers. In an odd twist, reports emerged of a second threat actor claiming to have compromised Icarus's infrastructure and attempting to re-extort Klue's customers. Regardless, the Klue breach highlights the growing threat of software-as-a-service (SaaS) supply chain compromises, particularly those exploiting OAuth tokens and trusted integrations to bypass traditional security controls.

  • In mid-June, security researchers identified a large-scale credential-harvesting and valid account abuse campaign dubbed “FortiBleed” that systematically targets internet-facing Fortinet FortiGate firewalls and SSL-VPN gateways, relying heavily on automated password spraying and configuration exfiltration rather than vulnerability exploitation. The scale of exposure and attack activity has been significant and globally distributed, with attackers collecting the login credentials of over 86,000 FortiGate devices across 194 countries. There is no singular ‘fix’ to mitigate the database exposure, and it is important that organizations work with their security teams, incident response providers, and other stakeholders to review environments holistically and monitor for signs of potentially unauthorized activity.

  • Multiple threat groups continue to leverage vulnerable drivers to bypass endpoint detection and response (EDR) solutions in a technique known as Bring Your Own Vulnerable Driver (BYOVD). Arete has observed Akira and DragonForce using the technique in multiple engagements, and The Gentlemen ransomware-as-a-service (RaaS) has also been observed using what researchers are calling "GentleKiller", a framework consisting of multiple variants that leverage vulnerable drivers and EDR-disabling utilities to target a wide range of endpoint security products.  

Sources

  • Arete Internal

Article

Update on FortiBleed Credential Exposure

Last week, security researchers identified a large-scale credential-harvesting and valid account abuse campaign dubbed “FortiBleed” that systematically targets internet-facing Fortinet FortiGate firewalls and SSL-VPN gateways. The campaign relies heavily on automated password spraying and configuration exfiltration rather than vulnerability exploitation.

  • Attackers first scan for exposed FortiGate devices and rank targets based on revenue. SSH brute-force attacks are used against admin accounts to gain initial access.

  • Following initial access, operators deploy stealthy packet-sniffing capabilities and establish external listening posts to receive harvested credentials and session data in near real time.

  • Observed post-exploitation activity strongly indicates pre-positioning for broader enterprise compromise, including lateral movement and potential ransomware deployment.

  • The scale of exposure and attack activity has been significant and globally distributed. The campaign has been ongoing since at least February 2026, with attackers collecting the login credentials of over 86,000 FortiGate devices across 194 nations.

How Arete Can Help

Arete continues to monitor this campaign, utilizing our extensive experience in detection, threat hunting, and attack surface review to look for indications of unauthorized activity related to this database exposure. Additional information regarding important considerations, containment and credential compromise mitigation actions, and additional hardening recommendations can be found in Arete’s FortiBleed Advisory.

Sources

  • FortiBleed: SOCRadar’s Investigation into 86,644 Compromised Fortinet Firewalls

  • FortiBleed Attackers Turn Firewalls Into Credential Stealers as Heists Persist

  • FortiBleed: The Most Detailed Breakdown Yet of an Active Russian Credential-Harvesting Operation

  • Hackers Using FortigateSniffer Tool That Turns Compromised Firewalls Into Password Collectors  

Article

Europol Disrupts AudiA6 Crypto Laundering Service

European authorities have dismantled AudiA6, a major cryptocurrency laundering service linked to ransomware groups and broader cybercriminal networks. Between 2022 and 2025, the platform is believed to have processed over €336 million in illicit funds, enabling threat actors to obscure financial trails and monetize cybercrime proceeds. Its operators are also suspected of running Dark2Web, a dark web forum that facilitated collaboration, services, and connections among cybercriminals globally. This development underscores the expanding role of sophisticated, large-scale cryptocurrency laundering services in sustaining the cybercrime economy, enabling threat actors to obscure illicit funds and evade regulatory controls.

What’s Notable and Unique 

  • Following law enforcement disruption of Cryptex and Garantex, AudiA6 emerged as another platform involved in financial activities linked to ransomware groups. Investigators believe that AudiA6 became a central hub for cybercriminals seeking to launder stolen digital assets while obscuring the transaction trail from authorities.

  • On June 10, 2026, a coordinated operation resulted in two arrests in Georgia, the dismantling of key infrastructure (30+ servers, 25 domains), the freezing or seizure of over €778,000 in crypto, and the takedown of the AudiA6 and Dark2Web platforms. 

Analyst Comments

Ransomware groups and cybercriminal networks are increasingly leveraging sophisticated techniques, including chain-hopping, decentralized exchanges, and mixer-as-a-service platforms, to rapidly move illicit cryptocurrency across multiple blockchains, effectively obscuring transaction trails. Concurrently, the widespread use of fraudulent exchange accounts, mule wallets, and privacy-enhancing tools has elevated cryptocurrency laundering to a core enabler of the cybercrime ecosystem, allowing actors to bypass anti-money-laundering controls at scale. This investigation identified over 6,000 KYC records linked to money-mule accounts, many of which were tied to Russian-speaking intermediaries specifically recruited to facilitate the movement of illicit proceeds. These threat actors systematically used both commercial and domain-controlled email services to establish mule accounts across multiple cryptocurrency platforms. Collectively, these findings underscore the growing scale, coordination, and professionalization of cryptocurrency-enabled crime, highlighting the critical need for sustained, intelligence-led, and internationally coordinated efforts to disrupt these evolving financial ecosystems.

Sources

  • Ransomware gangs cut off from EUR 336 million ‘AudiA6’ crypto laundering pipeline