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Good Europol Hunting: How Do You Like Them Apples, Emotet?

Combating Ransomware

On January 27, 2021, Europol announced that it had led a coordinated takedown of the Emotet infrastructure in collaboration with law enforcement authorities in the Netherlands, Germany, the United States, the United Kingdom, France, Lithuania, Canada, and Ukraine.

According to Europol, over the course of the operation, it has been able to map out and take control of servers from around the world that Emotet was using as “command-and-control” (C2) nodes. Europol also shared that it would use the seized servers to deactivate Emotet by pushing an update to all infected systems still connecting to the seized C2s. Analysis of the new Emotet updates, which were developed by Europol, shows code that will self-remove the Trojans from infected systems on March 25, 2021, at 12:00 (local time).

“As part of the criminal investigation conducted by the Dutch National Police into EMOTET, a database containing e-mail addresses, usernames and passwords stolen by EMOTET was discovered. You can check if your e-mail address has been compromised. As part of the global remediation strategy, in order to initiate the notification of those affected and the cleaning up of the systems, information was distributed worldwide via the network of so-called Computer Emergency Response Teams (CERTs).”

Source: Europol

The Ukrainian National Police agency also reported making some arrests in connection with this operation.


Mutable currency seized from Emotet

Emotet Overview

Emotet is a sophisticated banking Trojan that security researchers first identified in 2014. Originally, it was designed to steal banking credentials for use in taking over bank accounts and stealing funds from victims. Over the years, its functionality was updated to enable hackers to deploy supplementary malware and steal content from victims’ email systems.

In mid-2018, the Emotet group started to work closely with operators of the TrickBot banking Trojan and Ryuk/Conti ransomware groups. After initial infection, Emotet can stay undetected for weeks, sometimes months, before it eventually deploys the TrickBot Trojan, which can then lead to a subsequent ransomware attack. In the last few months, Emotet has also been seen deploying IcedID and Qbot Trojans, which can also lead to ransomware attacks by the MegaCortex, Prolock, and/or Maze/Egregor variants.

Emotet Risk Assessment

On October 12, 2020, Microsoft announced a similar takedown of the Trickbot infrastructure. In this case, the botnet’s owners were able to rebuild their infrastructure and restart operations in about four weeks. In part, this quick reboot was thanks to the Trickbot banking Trojan having a “fallback” communications module, which uses a blockchain distributed domain name service (DNS) technology called Emercoin DNS (EmerDNS) that law enforcement cannot take over. After the Trickbot operators deployed a new set of C2 servers, they were able to use the fallback channel to update configurations on infected systems.


It’s all about the money. Cold. Hard. Cash.

Unlike Trickbot, Emotet does not have a similar fallback capability and cannot regain access to infected systems to update configurations. Therefore, it will likely take the Emotet group longer to recover and resume operations. Based on the Arete Cyber Threat Intelligence (CTI) team’s assessment, the takedown of the Emotet C2 infrastructure will disrupt this botnet’s operations for at least five to six weeks.

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Red alert symbols and warning icons spreading across a digital network, representing firewall compromise and widespread cyber intrusion.
Red alert symbols and warning icons spreading across a digital network, representing firewall compromise and widespread cyber intrusion.

Article

FortiGate Exploits Enable Network Breaches and Credential Theft

A recent security report indicates that threat actors are actively exploiting FortiGate Next-Generation Firewall (NGFW) appliances as initial access vectors to compromise enterprise networks. The activity leverages recently disclosed vulnerabilities or weak credentials to gain unauthorized access and extract configuration files, which often contain sensitive information, including service account credentials and detailed network topology data. 

Analysis of these incidents shows significant variation in attacker dwell time, ranging from immediate lateral movement to delays of up to two months post-compromise. Since these appliances often integrate with authentication systems such as Active Directory and Lightweight Directory Access Protocol (LDAP), their compromise can grant attackers extensive access, substantially increasing the risk of widespread network intrusion and data exposure. 

What’s Notable and Unique 

  • The activity involves the exploitation of recently disclosed security vulnerabilities, including CVE-2025-59718, CVE-2025-59719, and CVE-2026-24858, or weak credentials, allowing attackers to gain administrative access, extract configuration files, and obtain service account credentials and network topology information. 


  • In one observed incident, attackers created a FortiGate admin account with unrestricted firewall rules and maintained access over time, consistent with initial access broker activity. After a couple of months, threat actors extracted and decrypted LDAP credentials to compromise Active Directory. 

  • In another case, attackers moved from FortiGate access to deploying remote access tools, including Pulseway and MeshAgent, while also utilizing cloud infrastructure such as Google Cloud Storage and Amazon Web Services (AWS). 

Analyst Comments 

Arete has identified multiple instances of Fortinet device exploitation for initial access, involving various threat actors, with the Qilin ransomware group notably leveraging Fortinet device exploits. Given their integration with systems like Active Directory, NGFW appliances remain high-value targets for both state-aligned and financially motivated actors. In parallel, Arete has observed recent dark web activity involving leaked FortiGate VPN access, further highlighting the expanding risk landscape. This aligns with the recent reporting from Amazon Threat Intelligence, which identified large-scale compromises of FortiGate devices driven by exposed management ports and weak authentication, rather than vulnerability exploitation. Overall, these developments underscore the increasing focus on network edge devices as entry points, reinforcing the need for organizations to strengthen authentication, restrict external exposure, and address fundamental security gaps to mitigate the risk of widespread compromise. 

Sources 

FortiGate Edge Intrusions | Stolen Service Accounts Lead to Rogue Workstations and Deep AD Compromise

Article

Vulnerability Discovered in Anthropic’s Claude Code

Security researchers discovered two critical vulnerabilities in Anthropic's agentic AI coding tool, Claude Code. The vulnerabilities, tracked as CVE-2025-59536 and CVE-2026-21852, allowed attackers to achieve remote code execution and to compromise a victim's API credentials. The vulnerabilities exploit maliciously crafted repository configurations to circumvent control mechanisms. It should be noted that Anthropic worked closely with the security researchers throughout the process, and the bugs were patched before the research was published. 

What’s Notable and Unique 

  • The configuration files .claude/settings.json and .mcp.json were repurposed to execute malicious commands. Because the configurations could be applied immediately upon starting Claude Code, the commands ran before the user could deny permissions via a dialogue prompt, or they bypassed the authentication prompt altogether. 


  • .claude/settings.json also defines the endpoint for all Claude Code API communications. By replacing the default localhost URL with a URL they own, an attacker could redirect traffic to infrastructure they control. Critically, the authentication traffic generated upon starting Claude Code included the user's full Anthropic API key in plain text and was sent before the user could interact with the trust dialogue. 


  • Restrictive permissions on sensitive files could be bypassed by simply prompting Claude Code to create a copy of the file's contents, which did not inherit the original file's permissions. A threat actor using a stolen API key could gain complete read and write access to all files within a workspace. 

Analyst Comments 

The vulnerabilities and attack paths detailed in the research illustrate the double-edged nature of AI tools. The speed, scale, and convenience characteristics that make AI tools attractive to developer teams also benefit threat actors who use them for nefarious purposes. Defenders should expect adversaries to continue seeking ways to exploit configurations and orchestration logic to increase the impact of their attacks. Organizations planning to implement AI development tools should prioritize AI supply-chain hygiene and CI/CD hardening practices. 

Sources 

  • Caught in the Hook: RCE and API Token Exfiltration Through Claude Code Project Files | CVE-2025-59536 | CVE-2026-21852

Article

Ransomware Trends & Data Insights: February 2026

After a slight lull in January, Akira and Qilin returned to dominating ransomware activity in February, collectively accounting for almost half of all engagements that month. The rest of the threat landscape remained relatively diverse, with a mix of persistent threats like INC and PLAY, older groups like Cl0p and LockBit, and newer groups like BravoX and Payouts King. Given current trends, the first quarter of 2026 will likely remain relatively predictable, with the top groups from the second half of 2025 continuing to operate at fairly consistent levels month to month.

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

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

  • In February, Arete observed Qilin actively targeting WatchGuard Firebox devices, especially those vulnerable to CVE-2025-14733, to gain initial access to victim environments. CVE-2025-14733 is a critical vulnerability in WatchGuard Fireware OS that allows a remote, unauthenticated threat actor to execute arbitrary code. In addition to upgrading WatchGuard devices to the latest Firebox OS version, which patches the bug, administrators are urged to rotate all shared secrets on affected devices that may have been compromised and may be used in future campaigns.


  • Reports from February suggest that threat actors are increasingly exploring AI-enabled tools and services to scale malicious activities, demonstrating how generative AI is being integrated into both espionage and financially motivated threat operations. The Google Threat Intelligence Group indicated that state-backed threat actors are leveraging Google’s Gemini AI as a force multiplier to support all stages of the cyberattack lifecycle, from reconnaissance to post-compromise operations. Separate reporting from Amazon Threat Intelligence identified a threat actor leveraging commercially available generative AI services to conduct a large-scale campaign against FortiGate firewalls, gaining access through weak or reused credentials protected only by single-factor authentication.


  • The Interlock ransomware group recently introduced a custom process-termination utility called “Hotta Killer,” designed to disable endpoint detection and response solutions during active intrusions. This tool exploits a zero-day vulnerability (CVE-2025-61155) in a gaming anti-cheat driver, marking a significant adaptation in the group’s operations against security tools like FortiEDR. Arete is actively monitoring this activity, which highlights the growing trend of Bring Your Own Vulnerable Driver (BYOVD) attacks, in which threat actors exploit legitimate, signed drivers to bypass and disable endpoint security controls.

Sources

  • Arete Internal