Cellcom Acknowledges Cyberattack After Major Service Disruption

Cellcom/Nsight, a leading regional telecommunications provider, has issued a heartfelt message to its customers following a five-day service disruption caused by a cyber incident.

In a letter signed by CEO Brighid Riordan, the company detailed the steps taken to restore service and safeguard customer data, emphasizing transparency, accountability, and community commitment.

Understanding the Cyber Incident and Response

The disruption, which began last week, was traced to a targeted cyber incident affecting a specific segment of Cellcom/Nsight’s network infrastructure.

According to Riordan, the attack did not compromise the systems where sensitive customer data, such as names, addresses, and financial information, is stored.

The company immediately activated its incident response protocol, which included:

• Engaging third-party cybersecurity experts to assess and contain the breach.
• Notifying federal and state authorities, including the FBI and Wisconsin officials, in compliance with cybersecurity incident reporting regulations.
• Implementing network segmentation to isolate affected systems and prevent lateral movement by threat actors.

The company’s swift response aligns with industry best practices for incident management, including the use of Security Information and Event Management (SIEM) systems and adherence to the National Institute of Standards and Technology (NIST) Cybersecurity Framework.

Technical Measures and Service Restoration

Cellcom/Nsight reported significant progress in restoring services, with a major milestone achieved the previous night.

The recovery process has been meticulous, prioritizing security and operational integrity over speed.

Key technical steps included:

• Forensic analysis of compromised servers using endpoint detection and response (EDR) tools.
• Restoration of core network services from clean, verified backups.
• Continuous monitoring for indicators of compromise (IOCs) and potential persistence mechanisms left by attackers.
• Patch management to address any exploited vulnerabilities, such as those identified by Common Vulnerabilities and Exposures (CVE) codes relevant to the attack vector.

Riordan assured customers that every phase of the recovery is being handled with care and precision, stating, “We will not rush anything that compromises safety, security, or trust.”

Customer Assurance and Future Commitment

Cellcom/Nsight has a legacy spanning 115 years, evolving from a local telephone provider to a modern telecommunications company.

The CEO acknowledged the inconvenience and hardship experienced by customers, offering compensation for the outage period: “We’re covering the time you were without service, and then some.”

The company reiterated its commitment to transparency, ongoing communication, and continuous improvement of its cybersecurity posture. Future initiatives include:

• Enhanced employee cybersecurity training to recognize and mitigate phishing and social engineering attacks.
• Regular penetration testing and vulnerability assessments are used to proactively identify and remediate security gaps.
• Investment in advanced threat intelligence platforms to detect and respond to emerging threats.

Riordan concluded the letter by expressing gratitude to both employees and customers for their resilience and support, promising that Cellcom/Nsight will emerge “better and stronger” from this experience.

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