CWE-1327: Binding to an Unrestricted IP Address

What is Binding to an Unrestricted IP Address?

• Overview: Binding to an unrestricted IP address occurs when a server binds to the address 0.0.0.0, allowing it to accept connections from any IP address, potentially exposing it to unintended networks and users.

• Exploitation Methods:

• Attackers can exploit this by scanning the network for open ports and accessing services not intended for public reach.
• Common attack patterns involve unauthorized access, data breaches, and lateral movement within networks.

• Security Impact:

• Direct consequences include unauthorized access and potential data theft.
• Potential cascading effects involve the compromise of additional network resources and services.
• Business impact could include data loss, service disruption, and reputational damage.

• Prevention Guidelines:

• Specific code-level fixes include binding services to specific IP addresses or interfaces that are intended to access the service.
• Security best practices involve regularly auditing network configurations and access controls.
• Recommended tools and frameworks include network scanners to identify open ports and firewalls to restrict access.

Corgea can automatically detect and fix Binding to an Unrestricted IP Address in your codebase. [Try Corgea free today](https://corgea.app).

Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Other

Affected Technologies: Web Server, Client Server, Cloud Computing

Vulnerable Code Example

Go Example

package main

import (
    "log"
    "net/http"
)

func main() {
    // Vulnerable: Binding server to all network interfaces (0.0.0.0)
    // This configuration allows access from any network, potentially exposing the application to unwanted attacks.
    err := http.ListenAndServe("0.0.0.0:8080", nil)
    if err != nil {
        log.Fatal(err)
    }
}

How to fix Binding to an Unrestricted IP Address?

To fix this vulnerability, bind your server to a specific IP address, limiting access to trusted networks only. This follows the principle of "least privilege," ensuring the application is accessible only from a controlled environment, such as a private network or the localhost, thereby reducing the attack surface.

1. Use Localhost for Development: Bind to 127.0.0.1 if the service is meant for local development only.
2. Use Internal Network IP for Production: Bind to a specific internal IP address to restrict access within your internal network.
3. Use Firewall Rules: Complement IP binding with proper firewall settings to restrict access even if the server is inadvertently bound to a broader address.

Fixed Code Example

package main

import (
    "log"
    "net/http"
)

func main() {
    // Fixed: Binding server to localhost (127.0.0.1)
    // This setup restricts access to the local machine, making it suitable for development environments.
    err := http.ListenAndServe("127.0.0.1:8080", nil)
    if err != nil {
        log.Fatal(err)
    }
}

In a production environment, replace "127.0.0.1:8080" with a specific IP address assigned to your server that is not publicly accessible. This ensures that only trusted network sources can reach the server, significantly reducing exposure to external threats. Additionally, always ensure that firewall rules are properly configured to complement this setup.