Quick Answer
The answer is a cross-site scripting (XSS) attempt. This is correct because the string %3Cscript%3Ealert('XSS')%3C/script%3E is simply the URL-encoded version of <script>alert('XSS')</script>, where %3C replaces < and %3E replaces >. In web server logs, attackers often encode script tags to bypass basic input filters, but the decoded payload reveals a classic reflected XSS injection designed to execute JavaScript in a victim’s browser. On the Computer Hacking Forensic Investigator CHFI exam, this scenario tests your ability to recognize encoded attack patterns in IIS logs, a common forensic artifact during web attack investigations. A frequent trap is mistaking URL encoding for benign data; remember that any sequence of %3Cscript%3E in logs should immediately raise suspicion. Memory tip: think of %3C and %3E as “less-than” and “greater-than” in disguise—when you see them together, decode and suspect XSS.
This CHFI practice question tests your understanding of application, email and cloud forensics. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
An analyst finds the following string in an IIS log: %3Cscript%3Ealert('XSS')%3C/script%3E. What does this indicate?
A cross-site scripting (XSS) attempt
The payload contains script tags intended to execute JavaScript.
A SQL injection attempt
Why wrong: SQL injection involves SQL syntax, not script tags.
A buffer overflow attempt
Why wrong: Buffer overflow payloads are binary or long strings, not encoded script tags.
A path traversal attempt
Why wrong: Path traversal uses '../' or '..\' sequences.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
A cross-site scripting (XSS) attempt
The string is URL-encoded HTML/JavaScript (<script>alert('XSS')</script>). It is a typical cross-site scripting payload attempting to execute in a browser.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
A cross-site scripting (XSS) attempt
Why this is correct
The payload contains script tags intended to execute JavaScript.
Related concept
Static NAT maps one inside address to one outside address.
A SQL injection attempt
Why it's wrong here
SQL injection involves SQL syntax, not script tags.
A buffer overflow attempt
Why it's wrong here
Buffer overflow payloads are binary or long strings, not encoded script tags.
A path traversal attempt
Why it's wrong here
Path traversal uses '../' or '..\' sequences.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
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
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CHFI NAT questions on configuration and troubleshooting.
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FAQ
Application, Email and Cloud Forensics — This question tests Application, Email and Cloud Forensics — Static NAT maps one inside address to one outside address..
The correct answer is: A cross-site scripting (XSS) attempt — The string is URL-encoded HTML/JavaScript (<script>alert('XSS')</script>). It is a typical cross-site scripting payload attempting to execute in a browser.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CHFI NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 21, 2026
This CHFI practice question is part of Courseiva's free EC-Council 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 CHFI exam.
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