A Cyberattack on an SME – Case Study and Lessons Learned

We dive into a fictional but realistic incident: a medium-sized company called Meyer & Söhne GmbH, with 100 employees, falls victim to a cyberattack. On a Friday evening, a customer service employee notices strange file names on the server. By Monday, the incident has escalated into a complete IT shutdown.

This case study shows step by step how an attack can unfold, what mistakes are made, and – in retrospect – what would have helped. The goal is to derive practical lessons for your own company from this story.

Phase 1: Attack Preparation (Unnoticed)

A few weeks before the visible attack, a bookkeeper at Meyer & Söhne receives an email that appears to come from a known supplier. Subject: “September invoice – important.” The employee opens the attachment (a Word document). Nothing happens – apparently. In reality, he has unknowingly opened the door for malware.

It installs itself as a Trojan and initially lies dormant in the system. Such precursor malware serves attackers to gain access to the company network and scout around (reconnaissance). At Meyer & Söhne, this attachment is not detected because the virus scanner on the PC was outdated and macros in Office were not disabled.

Phase 2: Escalation – The Attack Is Launched

Friday 5 p.m.: The Trojan downloads the actual ransomware from the internet. It begins to encrypt all files on the central server. Since hardly anyone is in the office at this time, it initially goes undetected.

The next morning, a service employee tries to access the VPN from home – it doesn’t work. He assumes a technical glitch. Only on Monday morning does the full extent come to light: none of the employees can log in, and on all computers there is a ransom message: “Your files are encrypted. Transfer €50,000 in Bitcoin within 7 days, or we will delete the key.” Panic ensues.

Phase 3: Response – The Race Against Time

Unfortunately, the company has no emergency plan. Valuable hours pass before it is clear who is making decisions. Finally, the managing director calls their IT service provider partner. They recommend: disconnect all systems from the network immediately (to stop the spread) and check the backups.

But the daily backup on the connected USB hard drive was also encrypted – it had been connected to the server the whole time, and the ransomware caught it too. No access to data, production is at a standstill, 100 people cannot work. Each day creates a loss of an estimated €20,000 in lost revenue and ongoing salary costs (by comparison: additional payroll costs and external forensics alone can quickly add up to over €100,000).

Management now involves the police (ZAC) and informs a service provider specializing in IT forensics. The cyber insurance – fortunately they had one – also brings in its experts. The decision is made not to pay the ransom, especially since it is unclear whether the extortionists would actually decrypt the data after payment and whether copies of the product drawings have already been taken (data exfiltration).

Instead, the forensics team attempts to salvage individual intact data fragments. In parallel, Meyer & Söhne proactively informs its customers that there will be delays – this reveals which customers are understanding and which are not.

Phase 4: Recovery and Aftermath

After just under a week, part of the IT can be restored with great effort from earlier, manually stored backups (a stroke of luck: an older backup from the previous year was stored offline in a safe, and the most important ERP data could be reconstructed from it).

Operations resume, but several weeks of work and current data are irretrievably lost. Total costs – downtime, external assistance, new acquisitions – add up to around €200,000. The company survives the incident thanks to insurance and reserves, but it is a wake-up call. Intensive security training, a better backup strategy (3-2-1 rule), and the establishment of an emergency plan follow. The IT infrastructure is also modernized.

Key Lessons from This Attack Scenario

Human Error as an Entry Point

Many attacks start with human error (here: opening a phishing attachment). Training and technical safeguards (e.g., macro blocking) would have significantly reduced the risk.

Backup Strategy Determines Survival

Backup, backup, backup: if Meyer & Söhne had had an externally stored, up-to-date backup, the extortion would have come to nothing. The 3-2-1 rule would have prevented the worst.

Emergency Plans Save Valuable Time

An emergency plan with clear responsibilities and prepared contacts (forensics, hotline, insurance) would have shortened the response time. In an emergency, every minute counts to contain damage.

Transparent Communication Builds Trust

Communication is crucial: internally (so everyone knows what to do) and externally (being transparent with customers). Meyer & Söhne maintained the trust of some customers because it communicated openly rather than sweeping things under the rug.

Prevention Is More Cost-Effective Than Recovery

Prevention is cheaper than recovery: after the incident, the company invests €50,000 in security (new firewalls, monitoring, training) – a sum that looks small compared to the €200,000 in damage.

Practical tip: Use this example as a basis to assess your own vulnerability. Ask yourself: would we have been better prepared than Meyer & Söhne? If not, act. Better to create one more backup in peacetime than to fight for every file in wartime.