Eurofiber Data Breach – Hackers Exploited Vulnerability to Exfiltrate Users’ Data

Eurofiber France recently discovered a serious security incident that affected its ticket management platform and customer portal systems.

On November 13, 2025, hackers exploited a software vulnerability in the platform used by Eurofiber France and its regional brands, including Eurafibre, FullSave, Netiwan, and Avelia.

The attack also targeted the ATE customer portal, which serves the company’s cloud division operating under the Eurofiber Cloud Infra France brand.

Through this exploit, the attackers managed to steal customer data from these platforms.

The breach remained limited to Eurofiber France customers and did not spread to other Eurofiber entities operating in Belgium, Germany, or the Netherlands.

The company immediately took action after detecting the intrusion. Within the first few hours, the ticketing platform and ATE portal were secured with stronger protections, and the exploited vulnerability was patched to prevent further unauthorized access.

Fortunately, sensitive information like banking details remained safe, as these were stored in separate systems that the attackers could not reach.

Security analysts at Eurofiber identified the breach quickly and activated their incident response procedures. The company worked alongside cybersecurity experts to contain the damage and secure affected systems.

Services continued running normally throughout the attack, meaning customers experienced no downtime or service interruptions despite the ongoing breach.

Eurofiber France followed all legal requirements by reporting the incident to French authorities. The company filed reports with CNIL, which is the French Data Protection Authority that enforces GDPR regulations, and notified ANSSI, France’s National Cybersecurity Agency.

Additionally, Eurofiber filed a complaint for extortion, suggesting the attackers may have attempted to demand payment or threaten further action.

Technical Response and Platform Security

The attack vector involved exploiting a software vulnerability within the ticket management platform infrastructure.

This type of vulnerability allowed the malicious actor to gain unauthorized access to the system and extract data without proper authentication.

The specific vulnerability type was not disclosed, but the platform’s architecture enabled the attacker to bypass normal security controls.

After detection, the security team implemented enhanced monitoring and access controls across both the ticketing platform and ATE portal.

These measures included stronger authentication mechanisms, improved logging capabilities, and additional network segmentation to prevent lateral movement within the infrastructure.

The rapid patching response demonstrates the importance of having incident response procedures ready to deploy when security incidents occur.

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