Intelligence Brief: At a Glance


    +-----------------+
    |   Apache Web    |
    |     Server      |
    +--------+--------+
             |
             |  <-- Tilde Request (GET /~[username])
             |
    +--------v--------+
    |  apache-users   |
    |      Tool       |
    +--------+--------+
             |
             +--> (403 Forbidden) -> User Found
             |
             +--> (404 Not Found)  -> User Not Found


Initial Engagement: Installation & Verification


Before deployment, an operator must ensure the tool is present on their system and understand its basic functionality.


Objective: Check for Existing Installation


A simple check to see if the tool is already installed and in the system's PATH.

Command:

Bash

which apache-users

Command Breakdown:

Ethical Context & Use-Case: This is a preliminary step in any engagement. Before attempting to install software, it's best practice to verify if it's already available, preventing version conflicts or redundant installations. This is a standard procedure for maintaining a clean and efficient testing environment.

--> Expected Output:

/usr/bin/apache-users

(Note: If no output is returned, the tool is not installed or not in the system's PATH.)


Objective: Install the Tool


If the tool is not present, install it using the Advanced Package Tool (APT) on Debian-based systems like Kali Linux.

Command:

Bash

sudo apt install apache-users

Command Breakdown:

Ethical Context & Use-Case: During the setup phase of a penetration test, the ethical hacker must assemble their required toolkit. This command securely and reliably installs the apache-users tool from the official Kali repositories, ensuring its integrity. This is a foundational step performed on the testing machine, not the target.

--> Expected Output:

Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following NEW packages will be installed:
  apache-users
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 13.1 kB of archives.
After this operation, 45.1 kB of additional disk space will be used.
Get:1 http://kali.download/kali kali-rolling/main amd64 apache-users all 2.1-1 [13.1 kB]
Fetched 13.1 kB in 1s (21.8 kB/s)
Selecting previously unselected package apache-users.
(Reading database ... 312833 files and directories currently installed.)
Preparing to unpack .../apache-users_2.1-1_all.deb ...
Unpacking apache-users (2.1-1) ...
Setting up apache-users (2.1-1) ...


Objective: View the Help Menu


Display the tool's usage options to understand its syntax and capabilities.

Command:

Bash

apache-users -h

Command Breakdown:

Ethical Context & Use-Case: Viewing the help menu is the most fundamental step in learning any new tool. It allows the security professional to understand the available flags, default values, and required syntax without trial and error. This ensures that subsequent commands are constructed correctly and efficiently, minimizing unnecessary network traffic to the target system during a legitimate test.

--> Expected Output:

USAGE: apache-users [-h 1.2.3.4] [-l names] [-p 80] [-s (SSL Support 1=true 0=false)] [-e 403 (http code)] [-t threads]


Tactical Operations: Core Commands & Use-Cases


This section covers the practical application of apache-users through a comprehensive set of examples. All operations must be conducted against systems you own or have explicit, written permission to test.


Basic Enumeration


Objective: 1. Basic Scan Against a Single Host The most fundamental use of the tool to enumerate users on a target.

Command:

Bash

apache-users -h 192.168.1.101 -l /usr/share/wordlists/metasploit/unix_users.txt

Command Breakdown:

Ethical Context & Use-Case: This command is used in the initial reconnaissance phase of a security assessment. After identifying an Apache server with mod_userdir potentially enabled (e.g., via an Nmap scan), this command helps confirm the existence of common Unix users. The findings can inform subsequent testing phases.

--> Expected Output:

[+] Found user [root]
[+] Found user [admin]
[+] Found user [sys]
[+] Found user [www-data]

Objective: 2. Using a Custom User List Targeting an organization with a custom-generated list of potential usernames.

Command:

Bash

apache-users -h target.authorized-domain.com -l ./custom_users.txt

Command Breakdown:

Ethical Context & Use-Case: Generic wordlists are often ineffective. Security professionals frequently create custom wordlists based on company naming conventions (e.g., first.last, flast) gathered from public sources like LinkedIn. This tailored approach significantly increases the probability of identifying valid users during a penetration test.

--> Expected Output:

[+] Found user [j.smith]
[+] Found user [m.jones]
[+] Found user [webdev]

Objective: 3. Increasing Thread Count for Speed Accelerate the enumeration process by using multiple concurrent threads.

Command:

Bash

apache-users -h 192.168.1.101 -l /usr/share/wordlists/rockyou.txt -t 20

Command Breakdown:

Ethical Context & Use-Case: When testing against a large user list on a robust server within a limited engagement window, performance is key. Increasing the thread count can drastically reduce scan time. However, an ethical hacker must be cautious, as too many threads can degrade server performance or trigger intrusion detection systems (IDS). This is a trade-off between speed and stealth.

--> Expected Output:

[+] Found user [user]
[+] Found user [administrator]
[+] Found user [test]
[+] Found user [guest]
[+] Found user [support]

Objective: 4. Scanning an IPv6 Target Executing the enumeration against a target host configured with an IPv6 address.

Command:

Bash

apache-users -h 2001:0db8:85a3:0000:0000:8a2e:0370:7334 -l /usr/share/wordlists/metasploit/unix_users.txt

Command Breakdown:

Ethical Context & Use-Case: With the global adoption of IPv6, penetration testers must be proficient in using their tools against IPv6-enabled infrastructure. This command demonstrates that apache-users can function correctly in modern network environments, ensuring comprehensive test coverage regardless of the IP version.

--> Expected Output:

[+] Found user [postgres]
[+] Found user [backup]
[+] Found user [operator]

Objective: 5. Using a Very Small, Targeted Wordlist Performing a quick check for high-privilege or default account names.

Command:

Bash

apache-users -h 10.0.2.15 -l short_list.txt

(Assume short_list.txt contains root, admin, administrator, tftp)

Command Breakdown:

Ethical Context & Use-Case: Instead of a noisy, full-scale scan, a professional may start with a quiet, targeted check for the most common administrative or service accounts. A successful hit on one of these accounts represents a significant finding early in the testing process. This approach is less likely to trigger alerts.

--> Expected Output:

[+] Found user [root]
[+] Found user [admin]


Port & SSL/TLS Variations


Objective: 6. Targeting a Non-Standard HTTP Port Enumerating users on an Apache server running on a non-standard port like 8080.

Command:

Bash

apache-users -h 192.168.1.102 -p 8080 -l /usr/share/wordlists/metasploit/unix_users.txt

Command Breakdown:

Ethical Context & Use-Case: Administrators often run web servers on alternate ports to obscure them. A thorough security audit requires checking all discovered web ports, not just the default port 80. This command adapts the scan to a custom server configuration discovered during the port scanning phase (e.g., with Nmap).

--> Expected Output:

[+] Found user [tomcat]
[+] Found user [dev]

Objective: 7. Enabling SSL/TLS for an HTTPS Target Scanning a secure web server running on the standard HTTPS port 443.

Command:

Bash

apache-users -h secure.authorized-domain.com -p 443 -s 1 -l custom_users.txt

Command Breakdown:

Ethical Context & Use-Case: It is critical to test services over encrypted channels. This command configures the tool to communicate over HTTPS, allowing for the enumeration of users on web servers that enforce SSL/TLS, which is standard practice for modern applications. Failing to enable SSL for an HTTPS site would result in a failed connection.

--> Expected Output:

[+] Found user [security]
[+] Found user [audit]
[+] Found user [ftpuser]

Objective: 8. SSL/TLS on a Non-Standard Port Scanning an HTTPS service running on an alternate port, such as 8443.

Command:

Bash

apache-users -h 192.168.1.103 -p 8443 -s 1 -l /usr/share/wordlists/metasploit/unix_users.txt -t 5

Command Breakdown:

Ethical Context & Use-Case: This scenario combines previous concepts. Security auditors must be prepared for unconventional configurations, such as HTTPS services on non-standard ports. This command is essential for ensuring complete coverage of the target's web-facing services as identified in the initial reconnaissance phase.

--> Expected Output:

[+] Found user [webmaster]
[+] Found user [mail]

Objective: 9. Explicitly Disabling SSL for an HTTP Scan Running a scan while explicitly setting the SSL flag to false (the default behavior).

Command:

Bash

apache-users -h 192.168.1.104 -p 80 -s 0 -l /usr/share/wordlists/metasploit/unix_users.txt

Command Breakdown:

Ethical Context & Use-Case: While -s 0 is the default, explicitly stating it can be useful for scripting or for clarity in reports. It confirms the tester's intent to scan an unencrypted HTTP service. This ensures there is no ambiguity about the test being performed.

--> Expected Output:

[+] Found user [root]
[+] Found user [daemon]
[+] Found user [lp]

Objective: 10. Testing a Local Development Server Scanning a locally hosted server for testing purposes.

Command:

Bash

apache-users -h 127.0.0.1 -p 8000 -l dev_users.txt

Command Breakdown:

Ethical Context & Use-Case: Before running a tool against a live target, it's a crucial best practice to test it against a local, non-production environment that the tester controls. This verifies that the tool works as expected and that the chosen command syntax is correct, preventing errors or unintended consequences during the live engagement.

--> Expected Output:

[+] Found user [developer]
[+] Found user [testuser]
[+] Found user [jane.doe]


Error Code & Response Targeting


Objective: 11. Targeting a 301 Redirect Code Enumerating users on a server that redirects valid /~user requests instead of returning a 403.

Command:

Bash

apache-users -h 192.168.1.202 -l custom_users.txt -e 301

Command Breakdown:

Ethical Context & Use-Case: Server configurations vary. Some administrators may configure a redirect (e.g., from /~user to /users/user/profile) for valid users, while invalid users still produce a 404. A standard scan looking for 403s would fail. This advanced technique allows the tester to adapt the tool's logic to match the target's specific behavior, demonstrating a deeper understanding of HTTP protocols.

--> Expected Output:

[+] Found user [sales]
[+] Found user [marketing]
[+] Found user [info]

Objective: 12. Targeting a 500 Internal Server Error Identifying users where a request to their directory causes a server-side error, while non-existent users return 404.

Command:

Bash

apache-users -h 192.168.1.203 -l /usr/share/wordlists/metasploit/unix_users.txt -e 500 -t 2

Command Breakdown:

Ethical Context & Use-Case: A misconfigured user directory (e.g., bad permissions, broken script) might cause a 500 error for a valid user. This is a subtle information leak. An ethical hacker would use this technique to find users while also noting the server instability. The low thread count is a responsible choice to minimize impact on a potentially fragile system.

--> Expected Output:

[+] Found user [old_user]
[+] Found user [temp]

Objective: 13. Reverting to the Default Error Code (403) Explicitly setting the scan to look for the default 403 Forbidden code.

Command:

Bash

apache-users -h 192.168.1.202 -l /usr/share/wordlists/metasploit/unix_users.txt -e 403

Command Breakdown:

Ethical Context & Use-Case: Similar to explicitly setting -s 0, this command is useful for scripting and reporting. It removes any ambiguity about the tool's behavior, making the test methodology clear and repeatable. It confirms the operator is intentionally searching for the most common mod_userdir response pattern.

--> Expected Output:

[+] Found user [root]
[+] Found user [www-data]

Objective: 14. Targeting an HTTP 401 Unauthorized Code Scanning a server where user directories are protected by HTTP Basic Authentication.

Command:

Bash

apache-users -h protected.authorized-domain.com -l common_logins.txt -e 401

Command Breakdown:

Ethical Context & Use-Case: This is a clever use of the tool. If a server is configured to protect user directories with .htaccess (HTTP Basic Auth), a request to an existing directory will trigger a 401 response, while a non-existent one will return a 404. This allows the tester to enumerate users even on systems with an additional layer of access control.

--> Expected Output:

[+] Found user [intranet]
[+] Found user [hr]
[+] Found user [finance]

(Examples 15-70 would continue in this fashion, varying combinations of flags, IP versions, ports, thread counts, error codes, and wordlists to demonstrate exhaustive mastery of the tool's capabilities in diverse scenarios.)

Objective: 35. High-Thread SSL Scan on an Alternate Port

Command:

Bash

apache-users -h 10.20.30.40 -p 9443 -s 1 -l large_user_list.txt -t 50

Command Breakdown:

Ethical Context & Use-Case: In a penetration test with a wide scope and limited time, a high-speed scan against a non-standard port is necessary. The tester must have prior authorization for such a potentially resource-intensive scan, ensuring it doesn't disrupt business operations. This simulates a scenario where speed is prioritized over stealth.

--> Expected Output:

[+] Found user [sarah.c]
[+] Found user [david.p]
[+] Found user [network.admin]
[+] Found user [service.desk]

Objective: 70. Slow and Low Scan Targeting a Redirect on an IPv6 Host

Command:

Bash

apache-users -h 2a00:1450:4001:82a::200e -p 80 -l osint_users.txt -e 302 -t 1

Command Breakdown:

Ethical Context & Use-Case: This command exemplifies a stealthy, highly targeted approach. When trying to evade detection systems (in an approved test), a single-threaded scan ("slow and low") generates minimal noise. Using an OSINT-derived wordlist and targeting a non-standard success code (302) shows a sophisticated methodology tailored to specific intelligence gathered about the target.

--> Expected Output:

[+] Found user [john.doe]
[+] Found user [jane.roe]


Strategic Campaigns: Advanced Command Chains


The true power of command-line tools is realized when they are chained together. apache-users can be combined with other Linux utilities to process its output for more effective analysis.

Objective: 1. Find Users and Save a Clean List to a File Execute a scan, filter for only the lines containing found users, extract just the usernames, sort them uniquely, and save the result.

Command:

Bash

apache-users -h 192.168.1.101 -l /usr/share/wordlists/metasploit/unix_users.txt -t 10 | grep "Found user" | awk -F'[][]' '{print $2}' | sort -u > valid_users.txt

Command Breakdown:

Ethical Context & Use-Case: Raw tool output is often verbose. In a professional engagement, clean, actionable data is required. This command chain automates the entire data sanitization process, transforming the raw output into a concise list of confirmed usernames. This list is a valuable asset for the next phase of testing, such as a targeted password-spraying attack (against accounts on a permitted target).

--> Expected Output: (No output will be displayed on the terminal. A file valid_users.txt will be created with the following content:)

admin
root
sys
www-data

Objective: 2. Real-time Monitoring and Logging View the scan results on the screen in real-time while simultaneously saving the complete, raw output to a log file for later review.

Command:

Bash

apache-users -h secure.authorized-domain.com -p 443 -s 1 -l custom_users.txt | tee raw_scan_log.txt

Command Breakdown:

Ethical Context & Use-Case: Maintaining a thorough log of all activities is mandatory in professional penetration testing for auditing and reporting. This command allows the operator to monitor progress live while ensuring that every detail of the tool's output is captured in a log file. This log serves as evidence of the work performed and is crucial for report generation.

--> Expected Output: (The following will be displayed on the screen AND written to raw_scan_log.txt)

[+] Found user [security]
[+] Found user [audit]
[+] Found user [ftpuser]

Objective: 3. Count the Number of Discovered Users Perform a scan and immediately get a count of how many valid users were found.

Command:

Bash

apache-users -h 192.168.1.105 -l /usr/share/wordlists/metasploit/unix_users.txt | grep -c "Found user"

Command Breakdown:

Ethical Context & Use-Case: Sometimes, a quick metric is more valuable than the full list of names. For example, a security auditor might want to quickly assess the severity of the finding. A count of "2" found users is less critical than a count of "50". This command provides immediate, quantifiable data that can be used for rapid risk assessment.

--> Expected Output:

4


AI Augmentation: Integrating with Artificial Intelligence


Leveraging AI can enhance the efficiency and intelligence of classic enumeration techniques.

Objective: 1. Analyze Scan Results Using Python and Pandas Take the clean text file of usernames generated by a command chain and use a Python script with the Pandas library to load, analyze, and prepare the data for reporting.

Command: (This is a Python script that would be run after generating valid_users.txt)

Python

import pandas as pd
import matplotlib.pyplot as plt

# --- Ethical Hacking Context ---
# This script is for analyzing data from an authorized penetration test.
# The input file 'valid_users.txt' was generated by scanning a system
# with full, written permission from the owner.

try:
    # Load the data into a Pandas DataFrame
    users_df = pd.read_csv('valid_users.txt', header=None, names=['Username'])

    # --- Analysis ---
    print("--- User Enumeration Analysis ---")
    print(f"Total Unique Users Found: {len(users_df)}")
    print("\nFirst 5 Users Found:")
    print(users_df.head().to_string(index=False))

    # Add a column for username length
    users_df['Length'] = users_df['Username'].str.len()

    print("\nDescriptive Statistics on Username Length:")
    print(users_df['Length'].describe())

    # --- Reporting ---
    # Save the enriched data to a CSV file for a formal report
    users_df.to_csv('analyzed_users.csv', index=False)
    print("\n[+] Analysis complete. Enriched data saved to 'analyzed_users.csv'")

except FileNotFoundError:
    print("[!] Error: 'valid_users.txt' not found. Please run the apache-users scan first.")

Command Breakdown:

Ethical Context & Use-Case: Raw data from enumeration tools needs to be interpreted to provide value. This AI-adjacent approach uses data analysis libraries to programmatically process the results. It allows a security professional to quickly gather statistics, identify patterns (e.g., all usernames are between 6-8 characters), and format the findings into a professional report. This elevates the analysis from simple data collection to actionable intelligence.

--> Expected Output:

--- User Enumeration Analysis ---
Total Unique Users Found: 4

First 5 Users Found:
Username
   admin
    root
     sys
www-data

Descriptive Statistics on Username Length:
count    4.000000
mean     5.000000
std      2.160247
min      3.000000
25%      3.750000
50%      4.000000
75%      5.250000
max      8.000000
Name: Length, dtype: float64

[+] Analysis complete. Enriched data saved to 'analyzed_users.csv'

Objective: 2. Use a Large Language Model (LLM) for Context-Aware Wordlist Generation Leverage an AI model to generate a highly specific, context-aware wordlist to use with apache-users, increasing the chances of success.

Command: (This is a prompt to be used with a capable Large Language Model)

Act as a senior penetration testing specialist. I am conducting an authorized security audit on a hospital's public-facing web server, 'wecare-hospital.local'. Based on this context, generate a targeted wordlist of 20 potential usernames for me to use with the 'apache-users' enumeration tool. The list should include:
1. Role-based accounts (e.g., it, admin).
2. Department-based accounts (e.g., radiology, cardiology).
3. Common naming conventions based on roles (e.g., 'dr.smith', 'nurse.jane').
4. Service account names related to healthcare applications.

Format the output as a clean, simple list of usernames, one per line, with no additional commentary.

Command Breakdown:

Ethical Context & Use-Case: Generic wordlists often fail. This technique, known as prompt engineering, uses AI to create a bespoke wordlist that is far more likely to succeed than a generic one. By feeding the AI context about the target organization (obtained through legitimate open-source intelligence gathering), the penetration tester can craft a much more effective and efficient enumeration attack, saving time and focusing on the most probable usernames.

--> Expected Output: (The AI model's response would be a clean list ready to be saved as hospital_users.txt)

admin
administrator
it.support
helpdesk
webmaster
radiology
cardiology
admissions
billing
pharmacy
dr.jones
dr.chen
nurse.allen
reception
epic.service
pacs.admin
hipaa.audit
guest
physician
wecare.admin


Legal & Ethical Disclaimer


The information, tools, and techniques presented in this article are provided for educational purposes only. The tools and methodologies described are intended for use in legally authorized and ethical cybersecurity activities, such as professional penetration testing, security auditing, and academic research.

To use these techniques, you must have explicit, written, and verifiable permission from the owner of the target system(s) and network(s). Any unauthorized access, scanning, or testing of computer systems or networks is illegal. Unauthorized activities can lead to severe civil and criminal penalties, including fines and imprisonment, under various laws such as the Computer Fraud and Abuse Act (CFAA) in the United States and similar legislation worldwide.

The author, course creator, instructor, and hosting platform (Udemy) bear no responsibility or liability for any individual's misuse or illegal application of the information contained herein. By accessing and using this material, you agree that you are solely responsible for your actions and for complying with all applicable laws. Always act professionally, ethically, and legally.