Authentication forms the foundation of digital security. When authentication fails, everything else collapses. Yet many organisations rely on authentication protocols with known weaknesses or implement strong protocols incorrectly.
Password-based authentication remains ubiquitous despite fundamental flaws. Humans choose weak passwords, reuse them across sites, and fall for phishing attacks. No amount of complexity requirements or rotation policies fully addresses these issues.
NTLM authentication in Windows environments poses serious risks. This legacy protocol supports relay attacks, where attackers intercept authentication attempts and forward them to other systems. Attackers who can position themselves on the network can authenticate as any user without knowing their password.
Kerberos provides stronger security than NTLM when properly implemented. However, misconfigurations create vulnerabilities. Weak encryption types, permissive delegation settings, and disabled pre-authentication enable various attacks. Attackers exploit these weaknesses routinely during penetration tests. Professional web application penetration testing specifically targets authentication mechanisms, attempting various bypass techniques in a controlled environment.
Certificate-based authentication offers strong security in theory. Implementation challenges include certificate lifecycle management, revocation checking, and protecting private keys. Organisations that deploy certificate authentication often overlook these critical details.
William Fieldhouse, Director of Aardwolf Security Ltd, notes: “Authentication vulnerabilities consistently appear during web application penetration testing. The specific weaknesses vary, but they typically stem from implementation mistakes rather than protocol flaws. Getting authentication right requires both strong protocols and careful implementation.”
Single sign-on solutions centralise authentication, improving user experience and security management. They also create single points of failure. Compromise of the SSO provider grants access to every integrated application. Defence in depth requires careful SSO security configuration.
OAuth and OpenID Connect dominate modern web authentication. These protocols are robust when implemented correctly. Common mistakes include inadequate redirect URI validation, accepting unsigned tokens, or failing to validate token issuer claims.
Token storage security matters tremendously. Access tokens grant access to protected resources. If an attacker steals tokens, they bypass authentication entirely. Secure storage in HTTP-only cookies or encrypted storage prevents many attacks.
Session management weaknesses often accompany authentication flaws. Predictable session IDs, inadequate session timeouts, or missing session invalidation after password changes all create risks. Sessions deserve the same security attention as initial authentication.
