Article
AKO Ransomware – Analysis
Arete Analysis

Summary
Since January 2020, Arete’s Incident Response (IR) team has responded to various AKO ransomware engagements against organizations in the finance, healthcare, and manufacturing sectors. Below we share observations on AKO’s ransom demands, initial access vectors, and operating model, as well as recommendations to protect against cyber threats like AKO.
—————————————————————————
Statistical Data on AKO ransomware from Arete’s metrics
The information listed below is based on AKO cases investigated by Arete IR since January 2020. 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 statistics based on handled engagements:
Arete has responded to AKO cases since January 2020 in the Finance, Healthcare, and Manufacturing sectors
The average ransom demand is 8 BTC
The maximum ransom demand paid in US dollars has been $150,000
The minimum ransom demand paid in US dollars has been $2,000
Data exfiltration was observed in incidents involving the Healthcare sector
The major infection vector has been Remote Access (RDP) at 67% of the time
Background
AKO ransomware has been around since at least January 2020 and is distributed via a ransomware-as-a-service (RaaS), which mirrors the software-as-a-service (SaaS) model offered by legitimate vendors. Like SaaS, RaaS is offered via cloud-based sub- scription models for a subscription fee and several RaaS groups use a partner, or franchise-like, structure. This structure is where the RaaS operator keeps a percentage of commission from every victim infected through their partners and pays the rest of the extorted funds to the partner or “franchise owner.” What makes the RaaS model so appealing and lucrative is they are specifically built to be easy to use and deploy. Typically, RaaS variants employ a portal where the partner only needs to download the ransom- ware, with no development or coding skills required. Most RaaS models even provide a fully staffed technical and customer support service, like you would find with a legitimate SaaS offering. The support is meant to help the franchise owner or partner get off the ground with their ransomware campaign.
There are various blogs 1-2 that have been written on AKO ransomware, so we will not go into detail in this section. In some of these reports, the malware was observed encrypting files on Windows systems and adding a .m9V742 files extension, Windows Defender is stopped, and the registry modified to prevent the antivirus software from starting again. Some antivirus tools detect the malware as MedusaLocker or MedusaReborn, but the AKO ransomware operators deny association with MedusaLocker and say that AKO is their own product. The threat actors also confirmed that it is part of their job to steal data from the compromised networks.
At the time of this writing, no known free decryptors for this ransomware variant were available.
Recommendations
Install an Endpoint Detection and Response 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
Implement a system enforced password policy to force users into changing passwords at least every 90 days
Implement multifactor authentication on RDP and VPN access
If not needed, eliminate vulnerable RDP ports exposed to the internet
Block a high number of SMB connection attempts from one system to others in the network over a short period of time
Perform dark web monitoring periodically to verify if data from the organization is available for sale in the black market
Perform penetration tests
Periodically patch systems and update tools
Monitor connections to the network from suspicious locations
Monitor downloads & uploads of files to file sharing services over non-standard hours, not commonly used in the organization
Monitor uploads of files from domain controllers to the internet
Monitor network scans from uncommon servers (e.g. RDP server)
Sources
Back to Blog Posts
Report
Arete's 2025 Annual Crimeware Report
Harness Arete’s unique data and expertise on extortion and ransomware to inform your response to the evolving threat landscape.
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



