UnauthorizedAccessException

Unauthorized access refers to gaining entry to a computer system, network, or data resource without permission from the owner or administrator. It covers both intrusions from outside and misuse of legitimate credentials beyond their authorized scope. Unauthorized access threatens confidentiality, integrity, and availability of information and services, and is a central concern in information security and law.

Common forms include credential theft via phishing or malware, brute-force or credential-stuffing attacks, exploiting software vulnerabilities, session hijacking, and insider misuse. Physical access to devices can also enable unauthorized access when safeguards are weak.

Legally, unauthorized access is typically prohibited as a crime or civil wrong. Jurisdictions may distinguish between mere access and unlawful or unauthorized use of data, and may require intent to obtain sensitive information or to cause harm. Notable regimes include the United States Computer Fraud and Abuse Act, the United Kingdom's Computer Misuse Act, and similar provisions elsewhere. In many places, penalties scale with harm, data sensitivity, and the offender's role.

Prevention focuses on reducing opportunities for unauthorized access. Key measures include least-privilege access, multi-factor authentication, strong password and credential hygiene, regular patching and vulnerability management, network segmentation, encryption of data in transit and at rest, continuous monitoring, and security awareness training. Incident response plans should cover detection, containment, eradication, recovery, and post-incident analysis.

Impact can include financial loss, reputational damage, regulatory penalties, and legal liability. Ethical considerations emphasize protecting user privacy while maintaining security, and ensuring lawful monitoring and auditing of access to information systems.