The answer is Basic authentication over HTTP, as this represents the most significant web application security weakness. Basic authentication transmits credentials in Base64-encoded plaintext, which is trivially decoded by any attacker capturing network traffic, exposing the username and password directly. Even when used over HTTPS, the credentials remain vulnerable because they are stored in the browser cache and server logs in plaintext, making them recoverable from the client or server side. On the Certified Information Systems Auditor CISA exam, this question tests your ability to distinguish between technical weaknesses and policy issues—many candidates mistakenly focus on session timeout or encryption strength, but the core risk is credential exposure at rest and in transit. A common trap is assuming HTTPS fully protects Basic authentication, but the cached credentials bypass that protection. Remember the memory tip: “Base64 is not encryption—it’s just wrapping a secret in clear plastic.”
CISA Practice Question: Information Systems Acquisition, Development and Implementation
This CISA practice question tests your understanding of information systems acquisition, development and implementation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Refer to the exhibit.
[WebApp]
BaseURL = https://app.example.com
AuthMethod = Basic
SessionTimeout = 600
Encryption = SSL
An IS auditor is reviewing the configuration for a web application. Which of the following is the MOST significant security weakness?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The authentication method is Basic
Basic authentication transmits credentials in Base64-encoded plaintext over the network, which is trivially decoded and captured by any attacker with access to the traffic. Even when used over HTTPS, the credentials are exposed in the browser's cache and server logs, making this the most significant weakness among the options.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The authentication method is Basic
Why this is correct
Basic authentication sends credentials in plain text if not over TLS; even with TLS, it's weaker than digest or certificate-based.
Related concept
Read the scenario before looking for a memorised answer.
✗
Session timeout is set to 600 seconds (10 minutes)
Why it's wrong here
While high, it is not as critical as weak authentication.
SSL is deprecated but still provides encryption; basic auth is a bigger risk.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on the deprecated SSL protocol (Option D) as the most significant weakness, overlooking that Basic authentication exposes credentials in a trivially reversible format regardless of the transport layer security.
Detailed technical explanation
How to think about this question
Basic authentication sends the Authorization header with a Base64-encoded string of 'username:password'. Base64 is not encryption; it is an encoding scheme that can be reversed instantly. An attacker performing a man-in-the-middle attack or reviewing server logs can extract credentials without any cryptographic effort. In contrast, SSL/TLS weaknesses typically require exploiting protocol vulnerabilities (e.g., POODLE, BEAST) which are more complex to execute.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CISA exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Information Systems Acquisition, Development and Implementation — This question tests Information Systems Acquisition, Development and Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The authentication method is Basic — Basic authentication transmits credentials in Base64-encoded plaintext over the network, which is trivially decoded and captured by any attacker with access to the traffic. Even when used over HTTPS, the credentials are exposed in the browser's cache and server logs, making this the most significant weakness among the options.
What should I do if I get this CISA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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