Take a look at the following attack on a Web Server using obstructed URL:Take a...

Comprehensive and Detailed Explanation:

The attack shown is a Directory Traversal Attack. It uses URL encoding (hexadecimal obfuscation) to bypass input filters and access unauthorized files such as /etc/passwd.

%2e = . (dot)

%2f = / (forward slash)

So, ../../../etc/passwd becomes %2e%2e%2f%2e%2e%2f%2e%2e%2f%65%74%63%2f%70%61%73%73%77%64

The best protection against this attack is to:

Normalize and sanitize user input on the server.

Deny directory traversal patterns, whether encoded or not.

Specifically reject or deny hex-encoded path characters (%2e, %2f, etc.)

Option A directly mitigates this by preventing the server from decoding and processing hex-encoded directory traversal attempts.

From CEH v13 Courseware:

Module 10: Web Application Hacking

Topic: Directory Traversal and Input Validation

Incorrect Options:

B: IDS can alert, but it’s reactive rather than preventative.

C: SSL encrypts communication but does not prevent path traversal.

D: Active script detection is unrelated to path traversal attacks.