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Colonial Pipeline Breached by Darkside Ransomware Group

Arete Analysis

Cyber Threats

On Saturday May 8, US Colonial Pipeline announced that they were victim of a ransomware attack that affected their network on Friday May 7.

US Colonial Pipeline is said to be the largest fuel pipeline in the United States and the main source of gasoline, diesel and jet fuel for the East Coast providing 45% of all fuel consumed on the East Coast.

To contain the threat, the company took certain systems offline, and these actions temporarily halted all pipeline operations and affected some of their IT systems. The company said that they have remained in contact with law enforcement and other federal agencies, including the Department of Energy who is leading the Federal Government response.

Arete Darkside Ransomware Group Analysis

Arete Incident Response has worked on multiple breach response engagements associated with the DarkSide ransomware group. The following are statistics and metrics from our DFIR engagements associated with this threat:

Sectors affected

  • Critical Infrastructure

  • Manufacturing

  • Professional Services

  • Public Service

  • Financial Services

  • High Technology/Engineering/Social Media

  • Retail

  • Average ransom demand in US dollars: 2,720,909

    • The highest ransom demand Arete observed has been 12 million dollars

  • Average ransom paid in US dollars: 1,548,509

  • Data exfiltration has been observed in 80% of the cases

FBI Response and Recommendations

Today, the FBI announced in their Twitter page that the DarkSide ransomware is confirmed to be the malware affecting Colonial Pipeline:

Image Source

The FBI also released an FBI FLASH alert MU-000146-MW coordinated with DHS-CISA and the Department of Energy. The alert confirms press reporting on Darkside infecting a critical infrastructure company in the United States and describes Darkside as a ransomware-as-a-service (RaaS) variant, in which criminal affiliates conduct the attacks and the proceeds are shared with the ransomware developer(s). It also mentions that Darkside has impacted numerous organizations across various additional sectors including manufacturing, legal, insurance, healthcare, and energy.

Recommended Mitigations by the FBI:

  • Backup data regularly, keep offline backups, and verify integrity of backup process.

  • Keep software updated. Install software patches so that attackers cannot take advantage of known problems or vulnerabilities.

  • Use two-factor authentication and strong passwords.

  • Audit logs for all remote connection protocols.

  • Audit logs to ensure all new accounts were intentionally created.

  • Scan for open or listening ports and disable SMBv1.

  • Consider disabling RDP if it is not being used.

  • Ensure anti-virus and anti-malware solutions are set to automatically update and regular scans are conducted.

  • Implement application whitelisting. Only allow systems to execute programs known and permitted by security policy.

  • Monitor Active Directory and local administrators group changes.

  • Maintain only the most up-to-date version of PowerShell and uninstall older versions.

  • Enable PowerShell logging and monitor for unusual commands, especially execution of Base64 encoded PowerShell.

  • Turn off the option to automatically download attachments. To simplify the process of reading email, many email programs offer the feature to automatically download attachments. Check your settings to see if your software offers the option and disable it.

Arete strongly recommends the use of advanced behavioral endpoint detection and response (EDR) technology to counter ransomware attacks! Advanced behavior EDR systems should include artificial intelligence (AI) and machine learning (ML). 

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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