Broken Authentication Interview Questions and Answers
Learn Broken Authentication with interview questions, Mermaid diagrams, Spring Security examples, OWASP guidance, and enterprise security best practices.
Broken Authentication - Interview Questions & Answers
Broken Authentication refers to security weaknesses that allow attackers to compromise user identities, steal credentials, hijack sessions, or bypass authentication mechanisms.
In the OWASP Top 10 (2021), this category is included under Identification and Authentication Failures.
Authentication is the first security boundary of every enterprise application. Weak authentication can result in complete system compromise.
Q1. What is Broken Authentication?
Answer
Broken Authentication occurs when an application's authentication process is implemented incorrectly, allowing attackers to impersonate legitimate users.
Examples include:
- Weak passwords
- Stolen credentials
- Session hijacking
- Missing MFA
- Weak JWT validation
- Predictable session IDs
Authentication Flow
flowchart LR
User --> Authentication
Authentication --> Application
Application --> ProtectedResources["Protected Resources"]
Q2. Why is Broken Authentication dangerous?
Answer
If attackers bypass authentication, they can gain access to protected resources as legitimate users.
Possible impacts include:
- Account Takeover
- Financial Fraud
- Data Theft
- Privilege Escalation
- Identity Theft
- Regulatory Violations
Attack Impact
flowchart TD
BrokenAuthentication["Broken Authentication"] --> AccountTakeover["Account Takeover"]
BrokenAuthentication["Broken Authentication"] --> DataTheft["Data Theft"]
BrokenAuthentication["Broken Authentication"] --> PrivilegeEscalation["Privilege Escalation"]
BrokenAuthentication["Broken Authentication"] --> FinancialLoss["Financial Loss"]
Q3. What are common causes of Broken Authentication?
Answer
Common causes include:
- Weak passwords
- Password reuse
- Missing Multi-Factor Authentication (MFA)
- Weak session management
- Long-lived sessions
- Hardcoded credentials
- Improper JWT validation
- Insecure password storage
Causes
mindmap
root((Broken Authentication))
Weak Passwords
No MFA
Session Hijacking
JWT Validation Issues
Password Reuse
Hardcoded Credentials
Long Sessions
Q4. What is Session Hijacking?
Answer
Session Hijacking occurs when an attacker steals a valid session identifier and uses it to impersonate the authenticated user.
The attacker does not need the user's password.
Session Hijacking
flowchart LR
User --> Login
Login --> SessionCookie["Session Cookie"]
SessionCookie["Session Cookie"] --> Attacker
Attacker --> Application
Prevention
- HTTPS
- HttpOnly Cookies
- Secure Cookies
- Short Session Timeout
Q5. How should passwords be stored securely?
Answer
Passwords should never be stored in plain text.
Use secure password hashing algorithms such as:
- BCrypt
- Argon2
- PBKDF2
- SCrypt
Password Storage
flowchart LR
Password --> HashAlgorithm["Hash Algorithm"]
HashAlgorithm["Hash Algorithm"] --> Database
Interview Tip
Hash passwords—not encrypt them. Password hashing is a one-way process designed for secure password storage.
Q6. How does Spring Security help prevent Broken Authentication?
Answer
Spring Security provides built-in authentication features.
It supports:
- BCrypt Password Encoder
- OAuth2
- OpenID Connect
- JWT Authentication
- Session Management
- Remember-Me
- MFA Integration
Spring Security
flowchart TD
User --> SpringSecurity["Spring Security"]
SpringSecurity["Spring Security"] --> AuthenticationManager["Authentication Manager"]
AuthenticationManager["Authentication Manager"] --> ProtectedApis["Protected APIs"]
Q7. What is Multi-Factor Authentication (MFA)?
Answer
MFA requires users to verify their identity using two or more authentication factors.
Examples:
- Password
- OTP
- Mobile Authenticator App
- Security Key
- Biometrics
MFA Flow
flowchart TD
User --> Password
Password --> OTP
OTP --> Application
Benefits
- Prevents credential theft attacks
- Protects against password reuse
- Reduces account takeover
Q8. What are common authentication mistakes?
Answer
Common mistakes include:
- Plain-text passwords
- Weak password policies
- Missing MFA
- Predictable session IDs
- Long-lived JWT tokens
- No account lockout
- Missing logout functionality
- Missing session expiration
Wrong Design
Password
↓
Database ❌
Correct Design
Password
↓
BCrypt
↓
Database ✅
Q9. How can Broken Authentication vulnerabilities be detected?
Answer
Detection methods include:
- Penetration Testing
- Authentication Audits
- OWASP ZAP
- Burp Suite
- Static Code Analysis
- Security Logs
- SIEM Monitoring
Security Pipeline
flowchart TD
Developer --> SecurityTesting["Security Testing"]
SecurityTesting["Security Testing"] --> PenetrationTesting["Penetration Testing"]
PenetrationTesting["Penetration Testing"] --> ProductionMonitoring["Production Monitoring"]
Q10. What are the enterprise best practices for preventing Broken Authentication?
Answer
Follow these best practices:
- Enforce strong password policies.
- Store passwords using BCrypt or Argon2.
- Enable Multi-Factor Authentication.
- Use HTTPS everywhere.
- Use secure session cookies.
- Keep JWT Access Tokens short-lived.
- Rotate Refresh Tokens.
- Lock accounts after repeated failed login attempts.
- Monitor authentication events.
- Follow Zero Trust principles.
Enterprise Authentication Architecture
flowchart TD
User --> IdentityProvider["Identity Provider"]
IdentityProvider["Identity Provider"] --> MFA
MFA --> OAuth2/OIDC
OAuth2/OIDC --> SpringSecurity["Spring Security"]
SpringSecurity["Spring Security"] --> Application
Authentication Security Pipeline
flowchart LR
Password --> BcryptMfaJwtAuthorization["BCrypt → MFA → JWT → Authorization → Protected API"]
Authentication Checklist
mindmap
root((Secure Authentication))
Strong Passwords
BCrypt
MFA
OAuth2
OpenID Connect
JWT
Secure Sessions
Monitoring
Senior Interview Tip
Broken Authentication is one of the leading causes of account compromise.
A production-ready enterprise authentication system should combine:
- Spring Security
- OAuth2
- OpenID Connect
- JWT
- BCrypt or Argon2
- MFA
- Secure Session Management
- HTTPS
- API Gateway
- SIEM Monitoring
- Zero Trust Architecture
Remember:
- Authentication verifies identity.
- Authorization determines permissions.
- Both must be implemented securely.
Quick Revision
- Broken Authentication allows attackers to impersonate legitimate users.
- Store passwords using BCrypt or Argon2.
- Never store passwords in plain text.
- Enable Multi-Factor Authentication.
- Protect sessions with Secure and HttpOnly cookies.
- Keep JWT Access Tokens short-lived.
- Rotate Refresh Tokens.
- Lock accounts after repeated failed login attempts.
- Monitor authentication events continuously.
- Combine Spring Security, OAuth2, OIDC, JWT, MFA, and Zero Trust for enterprise-grade authentication.