How to Use the 'nxc rdp' Command (with Examples)

The ’nxc rdp’ command is a tool used primarily for penetration testing and exploiting Remote Desktop Protocol (RDP) servers. RDP is a proprietary protocol developed by Microsoft, which provides a user with a graphical interface to connect to another computer over a network connection. The ’nxc rdp’ command can assist in identifying vulnerabilities, attempting to crack passwords, and capturing screen images of remote desktops that use RDP.

Use Case 1: Searching for Valid Credentials

Code:

nxc rdp 192.168.178.2 -u path/to/usernames.txt -p path/to/passwords.txt

Motivation for Using the Example:

This use case is essential for security professionals who need to assess the vulnerability of an RDP server by testing multiple combinations of usernames and passwords. Doing so can help identify weak credential systems that attackers could exploit, thereby allowing network administrators to strengthen their systems accordingly.

Explanation for Every Argument:

• 192.168.178.2: This is the target IP address of the RDP server where the credentials will be tested.
• -u path/to/usernames.txt: This specifies the path to a file containing a list of potential usernames to be tested against the server.
• -p path/to/passwords.txt: This specifies the path to a file containing a list of potential passwords to be tested.

Example Output:

Trying username: admin and password: 123456
Trying username: user1 and password: password
Valid credentials found: username: admin, password: secretpass

Use Case 2: Taking a Screenshot After Waiting for a Specified Time

Code:

nxc rdp 192.168.178.2 -u username -p password --screenshot --screentime 10

Motivation for Using the Example:

An essential aspect of vulnerability assessment is understanding what a successful login might see on their screen. Waiting for a period allows dynamic content to load or specific processes to initiate, making this feature valuable for capturing a more complete picture of the remote desktop environment.

Explanation for Every Argument:

• 192.168.178.2: The IP address of the RDP server you are connecting to.
• -u username: The username you are using to log into the RDP server.
• -p password: The password for the specified username.
• --screenshot: This flag tells the command to take a screenshot of the session.
• --screentime 10: Specifies a wait time of 10 seconds before taking the screenshot, allowing the desktop environment to load fully.

Example Output:

Logged in successfully. Waiting 10 seconds before taking a screenshot.
Screenshot saved to /path/to/screenshots/screenshot01.png

Use Case 3: Taking a Screenshot in a Specified Resolution

Code:

nxc rdp 192.168.178.2 -u username -p password --screenshot --res 1024x768

Motivation for Using the Example:

Custom resolution screenshots provide flexibility in documentation and reporting. Security analysts can specify the resolution to match the target display size or to optimize the screenshot file size for storage or analysis.

Explanation for Every Argument:

• 192.168.178.2: The IP address of the RDP server.
• -u username: The username used for the connection.
• -p password: The password for the username.
• --screenshot: Indicates that a screenshot should be taken.
• --res 1024x768: This specifies the resolution at which the screenshot should be captured.

Example Output:

Logged in successfully. Screenshot taken at resolution 1024x768.
Screenshot saved to /path/to/screenshots/screenshot02.png

Use Case 4: Taking a Screenshot of the RDP Login Prompt if Network Level Authentication is Disabled

Code:

nxc rdp 192.168.178.2 -u username -p password --nla-screenshot

Motivation for Using the Example:

Network Level Authentication (NLA) is a security feature that requires the user to authenticate before establishing an RDP connection. If NLA is disabled, an attacker or tester can potentially capture the login screen itself, which could reveal important information or vulnerabilities warranting further investigation.

Explanation for Every Argument:

• 192.168.178.2: Target RDP server’s IP address.
• -u username: The username used for the connection.
• -p password: Corresponding password for the username.
• --nla-screenshot: Instructs the tool to take a screenshot of the login prompt if NLA is not engaged.

Example Output:

NLA is disabled. Capturing screenshot of login prompt.
Screenshot saved to /path/to/screenshots/nla_login_prompt.png

Conclusion:

The ’nxc rdp’ command can serve as a powerful tool for network administrators and security professionals when assessing vulnerabilities in RDP servers. By using these different use cases, professionals can test credential strength, capture comprehensive views of remote desktops, and gather intelligence about the login environment to bolster security measures.