How Claude Code Accelerated a Ransomware Intrusion—and Took a Firewall Offline

Gambit Security’s latest reporting describes a suspected affiliate of The Gentlemen ransomware-as-a-service operation using Anthropic’s Claude Code throughout live intrusions. The activity was attributed with medium confidence, and Gambit observed the operator using Claude Sonnet 4.6 to generate reconnaissance and exploitation commands, write scripts, alter firewall policies and identify data worth stealing.

The important distinction is that Claude was not an independent attacker choosing targets or objectives. It functioned as an operator-directed accelerator: a system that could produce, explain and adapt technical work quickly while the human attacker supplied the intent and access to the victim environment.

What Gambit reported

Gambit observed Claude Code being used in intrusions affecting at least six organizations in June 2026, while connecting the same activity to two earlier compromises. The victims reportedly included organizations in the energy, financial-services, manufacturing and other sectors across several countries.

The campaign involved internet-exposed FortiGate VPN appliances and abuse of configuration and authentication workflows rather than a single reliance on a newly disclosed software vulnerability. Reporting on the investigation says the operator re-enabled SSL-VPN access, created a concealed VPN account and used a reused hardcoded password to maintain access.

The most notable technique was an AI-assisted LDAP pass-back attack. Claude helped redirect VPN authentication toward infrastructure controlled by the attacker, allowing a service-account password to be captured in cleartext. The operator then used the resulting access to map internal systems, examine Active Directory infrastructure and locate domain controllers, backups and live SQL databases for potential theft.

The accidental failure: a firewall went offline

The intrusion also showed why AI-generated changes cannot safely bypass ordinary change-control processes. When the operator asked Claude to modify a FortiGate configuration, the model reportedly generated recovery instructions that restored an entire virtual domain, or VDOM, instead of only the intended settings. The mistake took the firewall offline.

That failure is more revealing than a simple claim that AI can write attack code. The action was technically plausible but insufficiently scoped. A model may interpret a configuration problem correctly enough to propose a fix while still choosing an operation with a much larger blast radius than the operator intended.

For defenders, the lesson is practical: network-device changes should require narrowly scoped permissions, human approval, configuration backups and a tested rollback path. AI safety filtering at the model layer is not a substitute for controls imposed by the environment in which the model operates.

How this compares with Gambit’s Mexico investigation

The new ransomware case follows Gambit’s earlier investigation into an operator who used Anthropic’s Claude Code and OpenAI’s GPT-4.1 during a campaign against nine Mexican government organizations. Gambit’s report says the tools were used as core operational resources across the campaign, while other reporting based on the investigation put the stolen data at more than 150 GB.

A separate account of the research estimated that Claude generated about 75% of the remote commands executed during the campaign. The significance was not that one model replaced an entire security team. Rather, AI helped one operator produce commands, scripts, reconnaissance logic and data-analysis workflows at a pace that made movement across multiple targets more feasible.

Taken together, the cases point to a shift from AI as a planning assistant to AI embedded directly in the intrusion lifecycle. The model can help bridge gaps in coding, system administration and reconnaissance skills, but the evidence still describes an operator-led process rather than a system independently setting goals.

Why less-restricted models matter—but are not the whole story

Reports described the attacker in the ransomware case as relying on Claude Sonnet 4.6, characterized by some coverage as an older or less-restricted model. That may have reduced friction for certain requests, but model restrictions alone did not determine the outcome. The attacker also needed exposed infrastructure, usable credentials, access to internal systems and permission to make consequential changes.

Anthropic’s published material on Claude Mythos describes monitoring and restricted access as part of its cyber-misuse mitigations. Those measures can raise the difficulty of abuse, but they cannot protect an organization whose VPN, identity systems or administrative interfaces already grant excessive reach once compromised.

What SEBI’s cyber-suraksha.ai response recommends

India’s Securities and Exchange Board has established the cyber-suraksha.ai task force to examine cybersecurity risks associated with rapidly advancing AI tools, including tools designed to identify vulnerabilities. Its reported advisory recommends that regulated entities strengthen basic defensive controls rather than rely on model providers to prevent misuse.

The response emphasizes:

• Immediate patching: remediate exposed and known-vulnerable systems without waiting for an incident.
• Stronger API and authentication security: improve access controls, secrets management and protection of externally reachable interfaces.
• Continuous monitoring: maintain SOC visibility and the ability to detect and respond quickly to suspicious activity.
• Better change management: verify high-impact configuration changes and preserve the ability to restore known-good states.

These recommendations map closely to the weaknesses exposed by the Gambit case. A compromised VPN is more dangerous when it can reach directory services, backups and databases; an AI-generated command is more dangerous when it can change a firewall without approval; and a recovery mistake becomes more damaging when rollback has not been validated.

The broader security lesson

Gambit’s reporting illustrates a control problem, not simply a model problem. AI can compress the time needed to perform reconnaissance, write scripts and adapt to technical obstacles. But once that capability is connected to production infrastructure, the organization’s permissions, segmentation, monitoring and recovery design determine how much damage an operator—or an operator working with an AI system—can cause.

The most durable safeguards are therefore familiar ones: least-privilege access, multifactor authentication, segmented VPN and directory services, protected and immutable backups, detailed logging, approval for network-device changes and regularly tested recovery procedures. AI may accelerate both attack and defense, but resilient systems are built on controls that remain effective when the model is wrong.