Penetration Test
A penetration test is a planned, authorized attack on an IT system designed to uncover its weaknesses before real attackers exploit them. Experts probe in a controlled way whether and how far they can break into a network, an application or — as with an ERP system — into business-critical data.
A penetration test (pentest for short) is a simulated, explicitly commissioned attack on an IT system that security experts use to probe its vulnerability under real-world attack conditions. The goal is to find weaknesses in networks, servers, web applications or configurations and — where contractually permitted — to actively exploit them in order to show what damage a real attacker could do. Unlike a purely theoretical security report, a pentest therefore delivers not an abstract risk note but practical proof: this gap is real, this is how it can be exploited, and these are the consequences.
The test is strictly scoped and controlled. The client and the testers agree in advance on the scope, the target systems, the time window and the permitted methods in a written authorization — without this authorization the same action would be a criminal offense. At the end comes a report that ranks the vulnerabilities found by severity, documents the attack path in a comprehensible way and recommends concrete remediation measures. A penetration test is thus a central tool for reliably assessing the security level of a system instead of relying on assumptions.
At a glance
- Penetration test = authorized, simulated attack to uncover real vulnerabilities
- Always with written authorization and a clearly defined scope — otherwise a criminal offense
- Types: black-, grey- and white-box depending on the tester’s prior knowledge
- Delivers a prioritized report with proof, attack path and countermeasures
- Relevant for ERP systems because they concentrate central financial, customer and inventory data
How a penetration test works
A penetration test follows a structured process that is based on established methodologies such as the BSI guideline or the OWASP Web Security Testing Guide. It does not begin with hacking but with alignment: what may be tested, which systems are off-limits, how aggressively the testers may proceed and who can be reached in an emergency. Only once this framework has been fixed in writing does the actual technical work begin.
A pentest typically runs through several phases. In reconnaissance, the testers gather information about the target — open ports, software in use, version levels. This is followed by identifying potential vulnerabilities, actively exploiting them, and — where relevant — attempting to widen the privileges gained (privilege escalation) and to maintain control. Finally, all traces are documented and the system is restored to its original state.
The phases at a glance
As a mnemonic, the process is often broken down into five steps: preparation and scoping, information gathering, vulnerability analysis, active exploitation and reporting. The last step is the most valuable — a pentest without a clear final report with prioritized recommendations remains an end in itself. A good report addresses both the technical side (concrete fixes) and management (a business risk assessment) at the same time.
Types of penetration tests
Penetration tests differ above all in how much prior knowledge the testers receive and from which position they attack. In a black-box test they get hardly any information and act like an outside attacker — this is realistic but time-consuming. In a white-box test the source code, architecture and access credentials are laid open, which allows a deep, efficient assessment. The grey-box test sits in between and is the most common in practice because it balances effort and informative value.
In addition, tests are distinguished by attack position: an external test checks what is reachable from the outside over the internet — web shop, VPN access, mail server. An internal test simulates an attacker who is already inside the network, for example through a compromised employee account or malware. Further variants include tests of web applications and APIs, of cloud environments, of Wi-Fi, as well as social engineering tests that put the human factor (phishing, physical access) to the test.
Distinction: penetration test vs. vulnerability scan vs. audit
The term is often confused with related assessments. A vulnerability scan is a largely automated comparison of systems against known security gaps. It is fast and cheap but produces many false positives and does not prove whether a gap is actually exploitable. A penetration test often builds on such a scan but goes decisively further: people test manually, chain several vulnerabilities together and demonstrate the real damage.
A security audit, by contrast, primarily assesses processes, policies and conformity — for example against ISO 27001 — and works on a document- and sample-based basis without actively attacking. An even more comprehensive format is red teaming, in which a team attacks a company over an extended period and with the full range of methods (technical, physical, social engineering) in order to test its entire defensive capability. The pentest is the focused, technically practical core within this spectrum.
Penetration test in the ERP system
An ERP system is a particularly rewarding target because it concentrates a company’s most valuable data in one place: the customer and supplier master data, prices and terms, open orders, stock levels as well as financial and posting data. If an attacker gains access, the risks include data theft, manipulated purchase orders, redirected payments or a complete standstill of operations. A penetration test therefore specifically checks whether this central data base can be reached from the outside or via compromised accounts.
In the ERP context the test typically targets several layers: the web interface and login, the connected interfaces and APIs (for example to a shop, marketplace or shipping provider), the authorization concept as well as the underlying server and database layer. Common findings are overly broad roles, weak or missing multi-factor authentication, unpatched components and unsecured API endpoints. How the test is organized depends on the operating model.
Cloud ERP vs. on-premise: who may test what?
With a cloud ERP in a SaaS model, the provider operates the infrastructure — an unauthorized pentest against its systems is generally prohibited by contract and must be agreed in advance. The customer can and should, however, have their own access, roles, interfaces and individual customizations assessed. With an on-premise ERP or self-hosting, responsibility lies entirely with the company, which may commission the test correspondingly more broadly — from the application down to the underlying server.
Why penetration tests matter in the DACH region
Regular security assessments are not just good practice but increasingly mandatory. The GDPR requires appropriate technical protective measures for personal data and their ongoing review — a penetration test is a recognized means of demonstrating this due diligence. Security standards such as ISO 27001 likewise call for systematic vulnerability management that includes pentests. For operators of critical infrastructure (KRITIS) and under the NIS 2 implementation, these requirements are tightening further.
In practice, a pentest pays off twice over: it lowers the real risk of a costly incident, and it provides customers, auditors, insurers and supervisory authorities with documented evidence of due diligence. Repetition is important — a test is a snapshot in time. After major changes to the ERP, interfaces or infrastructure, as well as at fixed intervals (often annually), it should be carried out again, complemented by continuous patch management so that gaps that were once closed do not reopen.
Example
Example: pentest uncovers an open API at an online retailer
A mid-sized online retailer runs its ERP on self-hosting and has connected it to a shop and marketplaces via an API. Before connecting another sales channel, management commissions a grey-box penetration test of the ERP interfaces. The testers are given a normal user account and the API documentation, but no administrator rights.
Within a few days they find an API endpoint that returns order and customer data without a proper authorization check: with a simply incremented parameter, other customers’ orders including addresses and amounts can be retrieved. The report classifies the finding as critical, documents the exact attack path and recommends a server-side authorization check for each record. The company closes the gap before the rollout — a potential data protection incident subject to a reporting obligation is thereby prevented.
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