Helsinki’s NCSC-FI: Key Lessons from a Major Data Breach Response
▼ Summary
– A 2024 data breach in Helsinki exposed sensitive personal data of over 300,000 people, prompting a year-long investigation by Finland’s Safety Investigation Authority (SIAF/OTKES).
– The breach affected Helsinki’s Education Division (KASKO) and was traced to an outdated Cisco ASA 5515 firewall appliance last updated in 2016.
– Attackers used brute force and exploited a vulnerability via Cisco AnyConnect software to gain privileged access and steal 2TB of data, including documents from city employees and students.
– Initial estimates of affected individuals (120,000) were later revised to over 300,000, encompassing employees, students, and applicants for childcare benefits.
– Matias Mesia of Finland’s National Cyber Security Centre (NCSC-FI) shared insights at FIRSTCON on containment and mitigation strategies for similar cybersecurity incidents.
The 2024 Helsinki data breach serves as a critical case study for organizations worldwide, demonstrating both vulnerabilities in legacy systems and effective response strategies. When Finland’s capital suffered a massive cybersecurity incident exposing sensitive information of over 300,000 individuals, it triggered a comprehensive investigation by national authorities. The findings, published in mid-2025, revealed crucial insights that every security team should consider.
During a recent cybersecurity conference, Matias Mesia from Finland’s National Cyber Security Centre (NCSC-FI) detailed the breach timeline and response efforts. The attack targeted Helsinki’s Education Division through an outdated Cisco firewall appliance that hadn’t received security updates since 2016. Shockingly, the device had been without dedicated maintenance personnel since 2017.
Attackers initially used brute force methods before exploiting a remote connection vulnerability through Cisco AnyConnect software. After crashing the system, they accessed internal networks using compromised credentials found on dark web marketplaces. The breach escalated rapidly as attackers gained privileged access to critical systems including Active Directory, virtualization servers, and backup repositories.
What began as an estimated impact on 15,000 individuals soon ballooned to affect ten times that number. The stolen data—approximately 2TB containing 10 million documents—included sensitive information about city employees, students, benefit applicants, and their family members. The incident highlights how quickly initial damage assessments can underestimate true breach scope.
Helsinki’s response demonstrated several best practices worth emulating. The case underscores the dangers of unmaintained legacy infrastructure, particularly when organizational knowledge about systems gets lost through staff turnover. Security teams must prioritize asset management, ensuring all devices receive regular updates and have clear ownership. The Helsinki breach proves that even a single outdated appliance can serve as the weak link in an otherwise robust security chain.
For cybersecurity professionals, the lessons extend beyond technical remediation. The incident shows the importance of maintaining institutional knowledge about critical systems and establishing clear protocols for handling credentials. Perhaps most importantly, it demonstrates how quickly a localized breach can escalate into an organization-wide crisis without proper containment measures.
(Source: InfoSecurity)
