hardMultiple ChoiceObjective-mapped
CAS-004 Practice Question: A company's security team is reviewing the…
A company's security team is reviewing the integration of a legacy application that only supports NTLM authentication. The infrastructure must be updated to meet modern security standards. Which of the following is the BEST approach to mitigate the risk of using NTLM?
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
✓
Deploy an authentication federation service that translates modern Kerberos/SAML to NTLM for the legacy application.
Deploying an authentication federation service (such as ADFS or a SAML proxy) allows the legacy application to continue using NTLM internally while presenting a modern authentication interface (e.g., Kerberos or SAML) to clients. This mitigates the risk of exposing NTLM to the network and allows integration with modern identity providers without modifying the legacy application. Option A is incorrect because network isolation and IP whitelisting do not address the inherent vulnerabilities of the NTLM protocol itself. Option C is incorrect because upgrading to NTLMv2 still leaves the protocol susceptible to relay attacks and other weaknesses, and vendor patches may not be available or feasible. Option D is incorrect because disabling NTLM would break the application if it does not support Kerberos directly.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Place the application on an isolated network segment and restrict access with IP whitelisting.
Why it's wrong here
Isolation reduces exposure but does not fix the weak NTLM authentication; credentials could still be intercepted or relayed.
- ✓
Deploy an authentication federation service that translates modern Kerberos/SAML to NTLM for the legacy application.
Why this is correct
A federation service (e.g., ADFS with NTLM fallback) allows the application to use modern authentication while the broker handles the legacy protocol, reducing risk.
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Apply vendor patches to upgrade NTLM to NTLMv2 and enable extended protection for authentication.
Why it's wrong here
NTLMv2 is still vulnerable to relay attacks; extended protection helps but is not a complete solution and may not be available.
- ✗
Disable NTLM and force the application to use Kerberos directly.
Why it's wrong here
Legacy applications often cannot be reconfigured to use Kerberos; forcing it would break functionality.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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