Anonymous

Platform: hackerdna | Category: Infrastructure | Type: Challenge | Difficulty: Easy | OS: Linux | Author: XESXOR | Date: 2026-02-16 | Status: Solved Techniques: NA

Summary

Task: Pentest machine with hidden flag. Solution: FTP anonymous login discovered via nmap ftp-anon script, flag.txt downloaded with curl.

Anonymous — HackerDNA

Description

"Start the machine, hack the system, and find the hidden flags to complete this challenge and earn points!"

Target: 54.228.25.179 Flag format: UUID

Analysis

Simple reconnaissance task. The name "Anonymous" is a direct hint at FTP anonymous login. The task tests basic scanning and FTP skills.

Reconnaissance

Nmap scan with service detection and scripts:

 bash read-only • copy allowed Copy
nmap -sV -sC -p 21,22,53,80,443 54.228.25.179 --open -T4

Results:

Key output from nmap script ftp-anon:

21/tcp open  ftp     vsftpd 3.0.5
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_-rw-r--r--    1 0        0              37 ... flag.txt

Solution

Step 1: Scanning (nmap)

 bash read-only • copy allowed Copy
nmap -sV -sC -p 21,53,80 54.228.25.179 --open -T4

The ftp-anon script immediately showed:

• Anonymous login allowed (code 230)
• File flag.txt available in FTP root

Step 2: Downloading the flag (curl/FTP)

 bash read-only • copy allowed Copy
curl -s ftp://54.228.25.179/flag.txt --user anonymous:

‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

Result:

REDACTED

Done. Two steps — scanning and downloading the file.

Additional Reconnaissance (not required for the flag)

• FTP write access: Permission denied — server is read-only
• Web directory brute force (ffuf): Only index.html (200), standard .htaccess/.htpasswd/server-status (403)
• DNS (port 53): Not responding to dig queries
• Virtual hosts: Different Host headers return the same static page
• HTML source: Clean HTML, no hidden comments or flags

Lessons Learned

‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

1. Read the task name — "Anonymous" = FTP anonymous login
2. Nmap scripts (-sC) solve it — ftp-anon automatically checks anonymous access
3. curl supports FTP — curl ftp://host/file --user anonymous: is faster than a separate FTP client
4. Don't overcomplicate — task is solved in 30 seconds with two commands ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍