The answer is client-side input validation is insufficient and server-side validation is missing. This is the most significant weakness because client-side JavaScript validation is trivially bypassed by disabling scripts or using tools like Burp Suite, leaving the application completely exposed to SQL injection attacks. Without server-side validation, an attacker can inject malicious SQL commands directly into database queries, and the shared DBA-privileged account then amplifies the damage by allowing full data exfiltration. On the CISA exam, this question tests your understanding of the principle that all security controls must be defense-in-depth, not single-layer; a common trap is to focus on the WAF logs or the privileged account, but the direct cause of SQL injection is the missing server-side input validation. Remember the mnemonic: “Client-side is for convenience, server-side is for security.”
CISA Information System Auditing Process Practice Question
This CISA practice question tests your understanding of information system auditing process. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
A financial institution recently experienced a data breach where an attacker exfiltrated customer data through an SQL injection vulnerability in a web application. The IS auditor has been asked to review the application security controls. The web application is developed in-house and runs on an application server behind a web application firewall (WAF). The auditor reviews the WAF logs and finds that no SQL injection attacks were detected before the breach, but the logs show many blocked XSS attempts. The developer states that all input validation is performed on the client side using JavaScript. During the audit, the auditor also finds that the application uses a shared database account with DBA privileges for all connections. What is the MOST significant weakness that directly contributed to the breach?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Client-side input validation is insufficient and server-side validation is missing.
Option B is correct because client-side validation is easily bypassed, and lack of server-side validation allowed SQL injection. Option A is possible but not confirmed. Option C is a weakness but not the direct cause of SQLi. Option D is not supported by evidence.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Client-side input validation is insufficient and server-side validation is missing.
Why this is correct
Without server-side validation, the application is vulnerable to SQL injection.
Related concept
Authentication checks who the user is.
✗
The use of a shared DBA database account violates the principle of least privilege.
Why it's wrong here
This increases risk but did not directly cause the SQL injection.
✗
The WAF is misconfigured to detect only XSS attacks but not SQL injection.
Why it's wrong here
This might be a contributing factor, but the primary cause is lack of server-side validation.
✗
The application server is not patched against known SQL injection vulnerabilities.
Why it's wrong here
There is no evidence of unpatched vulnerabilities; the issue is design.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CISA questions on access control and AAA configuration.
Information System Auditing Process — This question tests Information System Auditing Process — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Client-side input validation is insufficient and server-side validation is missing. — Option B is correct because client-side validation is easily bypassed, and lack of server-side validation allowed SQL injection. Option A is possible but not confirmed. Option C is a weakness but not the direct cause of SQLi. Option D is not supported by evidence.
What should I do if I get this CISA question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CISA questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
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Question Discussion
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