CISSP Software Development Security Practice Question
A security architect is designing an authentication system. To prevent session fixation attacks, which secure design principle should be implemented?
⚠ Common exam trap
It's easy for candidates to confuse session fixation with session hijacking or general secure transmission, leading them to choose HTTPS or MFA, which are important but do not directly counter the fixation mechanism.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Regenerating session IDs after successful login
Session fixation attacks occur when an attacker forces a user to use a known session ID. Regenerating the session ID after successful login (e.g., via `session_regenerate_id()` in PHP or `HttpServletRequest.changeSessionId()` in Java) ensures that the pre-authentication session ID is discarded and a new, unpredictable one is issued, breaking the attacker's control.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Using HTTPS for all communications
Why it's wrong here
Using HTTPS encrypts the communication channel between the client and server, protecting the confidentiality and integrity of data in transit. However, session fixation occurs when an attacker forces a known session ID onto a victim *before* they authenticate. While the subsequent login and all session traffic would be encrypted, HTTPS does not prevent the application from associating the legitimate user's authenticated state with the attacker's pre-set session ID, thus failing to mitigate the core vulnerability.
- ✗
Setting session timeout to 30 minutes
Why it's wrong here
Setting a session timeout limits the duration an active session remains valid after a period of inactivity, which is crucial for reducing the window of opportunity for various session-related attacks. However, this practice does not directly prevent session fixation itself. An attacker can still fix a session ID on a victim's browser, wait for them to log in, and then immediately attempt to hijack the session before the timeout period expires, especially if the attacker is actively monitoring.
- ✗
Implementing multi-factor authentication
Why it's wrong here
Multi-factor authentication (MFA) significantly enhances the security of the login process by requiring users to provide two or more distinct verification factors, ensuring only legitimate users can successfully authenticate. However, MFA primarily strengthens the *initial authentication step* and does not inherently address how the application manages session identifiers *after* successful login. An attacker could still fix a session ID, and if the application doesn't regenerate it post-MFA, the session remains vulnerable to fixation.
- ✓
Regenerating session IDs after successful login
Why this is correct
Regenerating the session ID immediately after a user successfully authenticates is the most effective direct countermeasure against session fixation. This action ensures that any session ID an attacker might have previously forced upon the victim's browser becomes invalid and unusable. By issuing a completely new, cryptographically random session ID for the authenticated session, the application effectively severs the link between the attacker's known ID and the legitimate user's secure session, preventing unauthorized access.
Go deeper
Related to this question
Learn chapter
Security Governance and Principles
Key term
Authentication
Authentication is the process of verifying that someone or something is who or what it claims to be before granting access to a system or resource.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CISSP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISSP exam.