Certified Ethical Hacker (CEH v11) — Question 143

A network administrator discovers several unknown files in the root directory of his Linux FTP server. One of the files is a tarball, two are shell script files, and the third is a binary file is named `nc.` The FTP server's access logs show that the anonymous user account logged in to the server, uploaded the files, and extracted the contents of the tarball and ran the script using a function provided by the FTP server's software. The ps command shows that the nc file is running as process, and the netstat command shows the nc process is listening on a network port.
What kind of vulnerability must be present to make this remote attack possible?

Answer options

• A. File system permissions
• B. Privilege escalation
• C. Directory traversal
• D. Brute force login

Correct answer: A

Explanation

The correct answer is A, as improper file system permissions allowed an anonymous user to upload and execute files on the server. Privilege escalation (B) typically involves gaining higher access than allowed, while directory traversal (C) refers to accessing files outside the intended directory. Brute force login (D) involves guessing credentials, which is not relevant in this scenario since the access was through an anonymous account.