The megatrend of security is acquiring a new dimension in the course of digital transformation – particularly at the interfaces of money, data, and processes. This becomes particularly evident where operational routine intersects with cyber risks: in invoice processing.

One Monday, one email – and €40 million less

Friday evening, a call to the accounts department. A supplier politely reminds them of an outstanding invoice. The clerk is irritated – the payment was made long ago. On Monday, the IT department raises the alarm: the PDF invoice originally sent by email was intercepted en route, manipulated, and resent with a changed IBAN. A six-figure loss. Such incidents are on the rise. Business Email Compromise is considered by the FBI to be the most expensive form of cybercrime worldwide, with annual damages amounting to billions.

„In international comparison, Germany is a popular target for cybercrime.“

Carsten Meywirth – Head of Cybercrime Department, Federal Criminal Police Office

And yet, in many companies, the exchange of invoices still takes place via insecure channels: by email, unencrypted, often even without structured checks. Invoice exchange is no longer a mere accounting routine – but a strategic interface between compliance, IT and liquidity protection.
Cybercriminals know this and attack precisely where technical systems meet human routines. A fleeting glance at the sender, an unthinking click, a quick „sign-off“ under time pressure: such everyday actions offer ideal attack vectors. The damage is enormous. According to the Bitkom study „Wirtschaftsschutz 2024“ (Economic Security 2024), losses from cyberattacks in German companies now amount to €178.6 billion annually. The threat is highly professionalised: perpetrator groups work in a division of labour, use social engineering training, fake domains, compromised supplier data – and perfect timing. The European cybersecurity agency ENISA now counts so-called „Invoice and Payment Redirect Scams“ among the most dangerous threat trends in Europe.

Why invoices are the sweet spot for attackers

Invoices appear harmless, but that's precisely what makes them dangerous. They trigger cash flows and often run through established routines – ideal for social engineering.

Many attacks begin with a simple email. According to the 2024 Verizon Data Breach Investigations Report, 73% of all social engineering attacks are initiated via email. A seemingly harmless subject line, a PDF attachment – and the Trojan is already at work. What looks like a normal invoicing process is, in reality, a clever cover for an attack. Particularly insidious: intercepted invoices are forwarded in their original design – unnoticed. The problem is that PDF invoices sent by email can be manipulated and are difficult to trace. They cannot be automatically validated, they cannot be securely transmitted, and they offer no proof of authenticity.

In 2024, the Schleswig High Court ruled that those who send invoices without protection bear responsibility in the event of manipulation. This does not just apply to IT systems, but also to decision-making processes. In many medium-sized companies, invoices are still checked manually, with internal approval via email, ideally under time pressure. If a colleague „from above“ urgently requests a payment to be approved, employees often don't question it in their routine. This is how invoice receipt becomes the most dangerous entry point.

A drastic example: The attack on Südwestfalen-IT in autumn 2023 crippled over 70 municipalities – the cause: allegedly malware in an email attachment of an administrative process. For weeks, public infrastructure in parts of the region was offline.

Structure and Network: How Peppol and E-invoicing formats become a firewall

The introduction of structured e-invoicing formats, such as XRechnung or ZUGFeRD was for a long time considered a bureaucratic act. Yet, it offers precisely what conventional processes lack: integrity, transparency, and the ability to protect itself.

An e-invoice is a machine-readable data record in which all information is stored in a standardised format: amount, sender, tax rate, IBAN. Because these fields are clearly defined, they can be checked automatically – against orders, goods receipts, and budgets. A reconciliation that only occurs on a sample basis in classical processes runs fully automatically here. And as soon as an IBAN does not match the master data, the system raises an alarm. Crucial to this is the transmission path. Secure e-invoicing processes do not run via email, but via specialised networks such as Peppol. The transmission takes place there with end-to-end encryption – only between verified senders and recipients. Every step is traceable. Tampering is excluded.

The result: Invoice processing becomes not only more efficient, but also a digital line of defence, as validation and secure delivery become standard features of e-invoicing.

Duty with potential: Why acting now protects better than reacting later

From 1 January 2025, in Germany, the Duty to accept for structured e-invoices. Many companies see this as a purely technical change. But in reality, it opens up the opportunity to strategically realign their invoicing landscape – with security as the guiding principle. The BSI explicitly recommends: structured formats and secure transmission channels. The CyberRisikoCheck according to DIN SPEC 27076 provides a practical introduction to identifying and closing security-relevant gaps.

Those who act now will not only gain regulatory certainty but also modernise critical processes at the same time: with role-based approvals, automatic validation, and traceable audit trails. Platforms such as ivi E-Invoicing Platform can be implemented quickly, networks like Peppol offer a reliable infrastructure – certified, established, ready for use. The time to get started has never been better.

Forging a shield from duty

The structured e-invoice is more than just a new data format; it's a functional security tool. Used correctly, it becomes the finance department's firewall. It protects against manipulation, minimises human error, and replaces risky routines with automated, traceable processes. From authenticity to integrity and secure transmission, processes are created that can not only be managed efficiently but also defended effectively. Investing now in format standards, network connectivity, and system validation reduces the risk of payment defaults, protects cash flow, and enhances supply chain resilience.

In short: Those who rely on e-invoicing and secure networks protect what matters – and future-proof their business.

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