# Course #602: SSLsplit$ for Penetration Testing – Section 1: Introduction
## 1. Introduction to SSLsplit$
SSLsplit is a powerful tool used in penetration testing that enables interception and analysis of SSL/TLS encrypted traffic. In today’s web environment, where encryption has become the norm, the ability to inspect such traffic is critical for security professionals. This section provides a foundational understanding of SSLsplit, including its installation, configuration, and practical applications.
## 2. Installation and Configuration on Kali Linux
### 2.1 Prerequisites
Before installing SSLsplit, ensure that you have the latest version of Kali Linux installed and updated. Open a terminal and run the following commands to update your system:
"`bash
sudo apt update
sudo apt upgrade
"`
### 2.2 Installing SSLsplit
SSLsplit can typically be installed directly from the Kali repositories. To install SSLsplit, execute the following command in your terminal:
"`bash
sudo apt install sslsplit
"`
### 2.3 Configuration of SSLsplit
SSLsplit works by creating a transparent proxy that can intercept SSL/TLS traffic. To set it up, you will need to create a configuration file and SSL certificates.
#### 2.3.1 Create SSL Certificates
You must create a certificate authority (CA) certificate that SSLsplit will use to sign the certificates for the websites you intercept. Run the following commands to generate the CA key and certificate:
"`bash
mkdir -p ~/sslsplit-certs
cd ~/sslsplit-certs
openssl genrsa -out ca.key 2048
openssl req -x509 -new -nodes -key ca.key -sha256 -days 3650 -out ca.crt
"`
Make sure to answer the prompts accordingly, especially the Common Name (CN), which should be a recognizable name for your CA.
#### 2.3.2 Configure SSLsplit
Next, create a configuration file to specify how SSLsplit will operate. Create a new file named `sslsplit.conf`:
"`bash
nano ~/sslsplit.conf
"`
Insert the following configuration:
"`ini
# SSLsplit configuration
# Listen on port 8080 for HTTP traffic
http = on
http_address = 0.0.0.0
http_port = 8080
# Listen on port 8443 for HTTPS traffic
ssl = on
ssl_address = 0.0.0.0
ssl_port = 8443
# Path to CA certificate and key
ca_cert = ~/sslsplit-certs/ca.crt
ca_key = ~/sslsplit-certs/ca.key
# Directory to write logs
log_directory = ~/sslsplit-logs
# Logging options
log_level = info
"`
### 2.4 Start SSLsplit
To start SSLsplit using the configuration file you just created, run the following command:
"`bash
sudo sslsplit -D -l http,connect:/http -l https,connect:/https -c ~/sslsplit.conf
"`
The `-D` flag allows SSLsplit to run in the background, while the `-l` flags indicate the type of traffic to intercept and where to send this traffic.
## 3. Step-by-Step Usage of SSLsplit
### 3.1 Basic Usage
Once SSLsplit is running, it will listen on the specified ports. You need to configure the devices or browsers whose traffic you want to intercept to use your Kali machine as a proxy.
#### 3.1.1 Configuring a Browser
For a web browser, open the settings and navigate to the proxy settings. Typically, you would set your HTTP and HTTPS proxy to:
– HTTP Proxy: `
– HTTPS Proxy: `
Ensure that you install the CA certificate (`ca.crt`) you created earlier in the browser's trusted root certificate authorities to avoid SSL errors.
### 3.2 Real-World Use Cases
SSLsplit is commonly used in several real-world scenarios:
#### 3.2.1 Network Traffic Analysis
By intercepting encrypted traffic, security analysts can identify malicious behaviors that would be otherwise obscured. For instance, by analyzing the traffic from compromised endpoints, analysts can discover data exfiltration attempts or command-and-control (C2) communications.
#### 3.2.2 Security Assessments
As part of a penetration testing engagement, SSLsplit can help assess the security posture of web applications by identifying vulnerabilities such as improper SSL configurations, weak cipher suites, or even exposed sensitive information.
## 4. Detailed Technical Explanations
### 4.1 How SSLsplit Works
SSLsplit operates at the network layer, acting as a man-in-the-middle (MITM) proxy. When a client makes an HTTPS request, SSLsplit intercepts the traffic and presents its signed certificate (the one created from the CA). The client sees this certificate as valid because it trusts the CA’s root certificate you installed in the browser.
### 4.2 Traffic Flow
Here's a simplified view of the traffic flow with SSLsplit:
1. The client initiates a connection to an HTTPS server.
2. SSLsplit intercepts the connection and presents its own certificate.
3. The client validates SSLsplit’s certificate.
4. SSLsplit establishes a separate connection to the destination server.
5. Data is sent to and from the client and server, allowing SSLsplit to log or manipulate as needed.
## 5. Code Examples for WordPress Integration
If you want to integrate SSLsplit with a WordPress installation, you may want to log the intercepted traffic or perform analysis on it. Here’s a simple example of a WordPress function to log requests.
"`php
function log_intercepted_requests($request) {
$log_file = '/var/www/html/wp-content/uploads/intercepted_requests.log';
$data = sprintf(
"[%s] %s from %sn",
date('Y-m-d H:i:s'),
$request->get_request_uri(),
$_SERVER['REMOTE_ADDR']
);
file_put_contents($log_file, $data, FILE_APPEND);
}
add_action('init', 'log_intercepted_requests');
"`
## 6. Conclusion
SSLsplit is a versatile tool in the penetration tester’s arsenal, allowing for deep inspection of encrypted traffic. Its ability to create a transparent proxy makes it an invaluable resource for security assessments, traffic analysis, and research. Mastering SSLsplit equips you with essential skills for navigating today’s security landscape.
For further reading and resources, refer to:
– [SSLsplit Official Documentation](https://www.kali.org/tools/sslsplit)
– [OpenSSL Documentation](https://www.openssl.org/docs/)
– [Kali Linux Documentation](https://www.kali.org/docs/)
—
Made by pablo rotem / פבלו רותם