# Course #612: Mastering subjack$
## Section 1: Introduction to subjack$
Welcome to the first section of our course on mastering the subjack$ tool! In this part, we will dive deep into the world of subdomain takeovers, an increasingly common vector for attackers leveraging misconfigured cloud resources. Understanding how to exploit these vulnerabilities can be key in securing web applications effectively.
### Overview of subjack$
The subjack$ tool is a powerful open-source command-line utility designed to help security professionals identify and exploit subdomain takeover vulnerabilities. Subdomain takeover occurs when a subdomain points to a resource that has been deleted or is unclaimed on a third-party service, allowing an attacker to register that resource and hijack the subdomain.
### Why Use subjack$?
With the growing use of cloud services and dynamic resource allocation, the chances of subdomain takeover have increased. If a developer mistakenly points a subdomain to a cloud service that they later abandon, an attacker could potentially claim that resource and serve malicious content or capture sensitive user information. Understanding how to utilize subjack$ can help you protect against these threats.
—
## Installation and Configuration on Kali Linux
The installation of subjack$ on Kali Linux is relatively straightforward. Below, we will cover the necessary steps from installation to configuration.
### Step 1: Install Dependencies
Before installing subjack$, make sure that you have Go installed on your Kali Linux system, as subjack$ is written in Go. You can install Go by running the following command:
"`bash
sudo apt update && sudo apt install golang -y
"`
### Step 2: Install subjack$
To install subjack$, you can use the following commands in your terminal:
"`bash
# Navigate to your Go workspace
cd $GOPATH/src
# Clone the subjack$ repository
git clone https://github.com/haccer/subjack.git
# Navigate to the cloned repository
cd subjack
# Install subjack$
go get && go build
"`
### Step 3: Running subjack$
You can run subjack$ directly by executing the following command from the directory where you built the tool:
"`bash
./subjack
"`
For the first time you run it, you might need to configure your settings, which we’ll discuss in the next section.
### Step 4: Configuration
Subjack$ requires a configuration file to operate effectively. The default configuration file can be found in the root of the subjack$ directory and should resemble the following structure:
"`json
{
"providers": {
"Github": {
"type": "github",
"enabled": true
},
"Bitbucket": {
"type": "bitbucket",
"enabled": true
}
// Add additional providers as needed
},
"options": {
"timeout": 3
}
}
"`
You can customize this file according to your target environment and the providers you wish to check for vulnerabilities.
—
## Step-by-Step Usage
Now that we have installed and configured subjack$, let's look at how to use it effectively. This section will guide you through a real-world example of subdomain takeover testing using subjack$.
### Basic Command Structure
The basic syntax to run subjack$ is:
"`bash
./subjack -w [wordlist.txt] -t [number_of_threads] -o [output.txt]
"`
– `-w`: The path to your wordlist containing subdomains.
– `-t`: The number of concurrent threads to run (to speed up the process).
– `-o`: The output file to save results.
### Example Wordlist
Create a text file named `subdomains.txt` with the following sample subdomains:
"`plaintext
www.example.com
api.example.com
test.example.com
"`
### Performing a Subdomain Takeover Test
Now let's perform a test using our subdomains. Here’s how you would run subjack$:
"`bash
./subjack -w subdomains.txt -t 100 -o results.txt
"`
This will check each subdomain in `subdomains.txt` and report any vulnerabilities found into `results.txt`.
### Interpreting the Results
Once the scan is complete, you can open the `results.txt` file to review any findings. The output will typically include:
– **Subdomain**: The subdomain that was checked.
– **Provider**: The cloud provider associated with the subdomain.
– **Potential Vulnerability**: Indicating whether a takeover was possible.
#### Sample Output:
"`
Subdomain: api.example.com
Provider: Github
Potential Vulnerability: YES
"`
—
## Real-World Use Cases
Subjack$ is essential for penetration testers and security analysts. Below are a few real-world use cases illustrating its importance:
### Use Case 1: Security Assessments for Clients
When performing security assessments for clients, using subjack$ can help identify vulnerable configurations in their subdomains. You can quickly identify any abandoned services or mismanaged resources that could lead to potential breaches.
### Use Case 2: Monitoring Your Own Infrastructure
Continuous monitoring of your own infrastructure for potential subdomain takeovers is essential. By regularly running subjack$, you can stay ahead of attackers and mitigate risks before they exploit your vulnerabilities.
### Use Case 3: Bug Bounty Programs
Many organizations run bug bounty programs that reward researchers for identifying vulnerabilities within their platforms. Utilizing subjack$ in your testing could help you find subdomain takeovers, allowing you to contribute valuable insights and potentially earn rewards.
—
## Detailed Technical Explanations
Subjack$ leverages various cloud service providers' APIs to check for potential vulnerabilities. Here’s a breakdown of how subjack$ functions:
### How Subjack$ Works
1. **Wordlist Processing**: Subjack$ begins by processing a list of subdomains.
2. **API Calls**: It makes API calls to various providers to see if the subdomain is linked to any services that can be claimed.
3. **Evaluation**: The responses are evaluated to determine if the subdomain is vulnerable to takeover.
4. **Reporting**: The findings are compiled and presented in an easy-to-read format, facilitating further action.
### Understanding Subdomain Takeover Vulnerabilities
A subdomain takeover typically occurs under these circumstances:
– **Deleted Resources**: A subdomain pointing to a previously used resource that has been deleted without proper cleanup.
– **Unclaimed Services**: A subdomain pointing to a cloud service that is not currently claimed by any user.
– **Misconfiguration**: An incorrect DNS configuration that leads to the unresolved mapping of a subdomain.
### Protecting Against Subdomain Takeover
To protect against these vulnerabilities, organizations can take several measures:
– **Regular Audits**: Conduct regular checks of your DNS configurations.
– **Monitoring**: Use tools like subjack$ to proactively monitor for potential vulnerabilities.
– **Proper Cleanup**: Ensure that resources are cleaned up correctly when they are no longer needed.
– **Documentation**: Maintain proper documentation of your cloud resources to avoid orphaned subdomains.
—
## External Reference Links
– [Kali Linux Tools – subjack$](https://www.kali.org/tools/subjack$)
– [OWASP Subdomain Takeover Article](https://owasp.org/www-community/attacks/Subdomain_takeover)
– [GitHub Repository for subjack$](https://github.com/haccer/subjack)
– [Cloud Provider Documentation on DNS Settings](https://cloud.google.com/dns/docs)
—
## Code Examples for WordPress
When testing WordPress sites, you may often run into scenarios where subdomain takeover can occur. Below are some code examples for WordPress that help visualize how to set up and check for vulnerabilities.
### Setting Up Subdomains in WordPress
In WordPress, you can create subdomains through your hosting provider’s control panel. Ensure that you properly manage these subdomains to prevent orphaned resources. Here’s a basic example of how to add a subdomain in your DNS settings:
"`plaintext
Type: A
Host: blog
Value: 192.0.2.1 (Your WordPress Server IP)
TTL: 3600
"`
### Checking Vulnerability via WP-CLI
If you have WP-CLI installed, you can also perform a quick sweep of your WordPress site for any potential vulnerabilities:
"`bash
wp plugin list –status=inactive
"`
This command will help you identify any inactive plugins that could be linked to your subdomains or create possible exploits.
### Example of a Vulnerable Plugin
"`php
// Example vulnerable plugin code that could allow an attacker to take over subdomain
function vulnerable_function() {
$subdomain = $_GET['subdomain'];
// Dangerous usage of user input leading to potential exploitation
eval("include 'http://$subdomain.example.com/malicious_code.php';");
}
"`
This is an example of poor coding practice that could lead to a successful takeover. Always sanitize user input!
—
In conclusion, mastering the subjack$ tool allows you to identify and mitigate potential subdomain takeover vulnerabilities effectively. Now that you have the tools necessary to get started, the next sections will dive deeper into advanced usage scenarios, further enhancing your pentesting skill set.
—
Made by pablo rotem / פבלו רותם