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Credential Stuffing
Definition
Credential stuffing is an attack in which stolen usernames and passwords from previously leaked databases are tried against other services. It exploits password reuse.
Credential stuffing exploits the reality that many people reuse the same password across multiple services. Attackers buy or steal databases of credentials and use automated tools to try those combinations at massive scale.
Unlike brute force, the passwords used have already been proven valid at another service. This makes the attack more efficient and harder to detect.
Defence: multi-factor authentication (MFA), detection of suspicious login patterns, have-i-been-pwned checks and encouraging users to use unique passwords via a password manager. The scale of credential stuffing is enormous: over 15 billion stolen credentials are available on the dark web (Digital Shadows, 2023). Modern credential stuffing tools use IP rotation, delays and browser emulation to bypass rate limiting and CAPTCHA protection. Successful logins are resold on the dark web or used for further attacks. Password managers and unique passwords per service are essential to reduce the risk.
Impact on organisations
The impact on organisations is substantial. Under NIS2, organisations in critical sectors are required to implement appropriate technical and organisational measures. DORA sets comparable requirements for financial institutions. The average cost of a security incident amounts to millions of euros in recovery, legal fees and reputational damage. National cybersecurity centres warn that advanced threat actors increasingly target European organisations.
Protection
Effective protection requires a layered approach combining technical measures with organisational processes and awareness. Regular testing of security measures through pentests and security assessments is essential. An incident response plan with clear roles and communication lines prepares the organisation for worst-case scenarios. Continuous monitoring through an MDR service or internal SOC detects threats before they can cause damage. Security awareness training ensures employees recognise and report suspicious activities.
The threat landscape evolves rapidly. Organisations that operate only reactively face increasing risk. A proactive security strategy combines technical measures with regular security testing, continuous monitoring and a practised incident response team. NIS2 requires organisations in critical sectors to implement demonstrable security measures, including supply chain risk management and regular assessments. The cost of prevention is a fraction of the cost of a security incident: the IBM Cost of Data Breach Report 2024 documents average costs of $4.88 million per incident. Organisations with an MDR service or practised incident response team save an average of $2.66 million per incident compared to organisations without preparation.
How DEFION helps
DEFION offers a comprehensive portfolio of security services that help organisations address this threat. The 24/7 SOC team continuously monitors for suspicious activities. Pentests and red teaming exercises test the effectiveness of existing security measures. In the event of an incident, the DFIR team is immediately available for forensic investigation and recovery. This requires a proactive security strategy that is regularly tested and updated based on the current threat landscape. Organisations that invest in prevention and preparation save significantly on incident response costs. ISO 27001 provides a proven framework for structurally organising information security.