EXPLORE

Article

ALPHV/BlackCat Ransomware Group Claims Responsibility for MGM Resorts Attack

Cyber Threats

Threat Actors

Summary

The ALPHV/ BlackCat ransomware group claimed responsibility for the MGM Resorts cyberattack in September 2023. The attack disrupted MGM’s operations, including slot machines, ATMs, and payment systems, causing significant financial and operational damage. Arete’s detailed analysis highlights ALPHV/BlackCat’s methodologies and the sectors affected by their attacks.

MGM Resorts recently identified a cybersecurity issue affecting certain of the Company’s systems. Promptly after detecting the issue, we began an investigation with assistance from leading external cybersecurity experts. We also notified law enforcement and are taking steps to protect our systems and data, including shutting down certain systems. Our investigation is ongoing, and we are working diligently to resolve the matter. The Company will continue to implement measures to secure its business operations and take additional steps as appropriate.

This incident also resulted in significant financial impact. According to NASDAQ, shares of the company’s stock have fallen 7.9%, from $43.74 to $40.29, between September 8 and 18.

The ALPHV (aka BlackCat) ransomware group claimed responsibility for this attack.

Update from ALPHV’s Dark Web Site

Arete has gained a deep understanding of ALPHV/BlackCat operations by working with nearly 100 clients impacted by the ransomware group since 2021. Arete’s Threat Intelligence team monitors multiple data leak sites and discovered that on September 14, the ALPHV group claimed they gained access to the MGM network on September 8. After multiple failed attempts to get in touch with the victim, ALPHV released their ransomware payload to more than 100 ESXi hypervisors in MGM’s network environment:

Source: Arete


Source: Arete


In this post, the group states:

“Their network has been infiltrated since Friday.”

“After waiting a day, we successfully launched ransomware attacks against more than 100 ESXi hypervisors in their environment on September 11th after trying to get in touch but failing. This was after they brought in external firms for assistance in containing the incident.”

“The ALPHV ransomware group has not before privately or publicly claimed responsibility for an attack before this point.”

“We still continue to have access to some of MGM’s infrastructure. If a deal is not reached, we shall carry out additional attacks. We continue to wait for MGM to… reach out as they have clearly demonstrated that they know where to contact us.”

Insights on ALPHV/BlackCat

Arete’s mid-year Turning Tides – Navigating the Evolving World of Cybercrime, highlighted ALPHV/BlackCat as one of the top ransomware groups observed in the second half of 2022 (H2 2022) and the first half of 2023 (H1 2023) based on data from our incident response engagements.

Source: Arete

Additional data also reveals that ALPHV/BlackCat remains one of the top three threat actor groups observed by Arete since Q3 of 2022.

Source: Arete

Below are insights on ALPHV based on Arete’s incident response engagements:

  • Sectors affected include entertainment, critical infrastructure, financial services, healthcare, manufacturing, professional services, public services, and retail.

  • Average ransom demand: $1,992,971

  • Percentage of time data exfiltration occurs: 70%

  • Average business downtime: 5.3 days

  • Tools used: CobaltStrike, Mimikatz, Megasync, LaZagne, and WebBrowserPassView

  • ALPHV/BlackCat uses various entry points to infect the victim’s network, including phishing emails, compromised credentials, and remote desktop protocol (RDP) brute force attacks.

  • Other malware is used as a stepping stone to launch the ransomware payload.

  • To increase potential reach and impact, the group targets both Windows and Linux devices, as well as network-attached storage (NAS) devices, which are often used to store backups and sensitive data.

To learn more about ALPHV/BlackCat and how to protect your organization from cyberattacks, download Turning Tides – Navigating the Evolving World of Cybercrime.

Our team of experts is here to assist you with this and any other related cyber incidents. Available services include Incident Response & Forensics, Threat Actor Negotiations, Crypto Operations, Security Operations (SOC), Restoration, and Threat Intelligence.

Cyber Emergency Hotline: 866.210.0955

New Engagements: Arete911@AreteIR.com

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.

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