CVE-2007-2447: Samba “username map script” Command Injection

CVE-2007-2447 is a critical remote command execution vulnerability affecting legacy versions of Samba. The issue stems from improper input sanitization when the username map script feature is enabled, allowing attackers to inject and execute arbitrary commands with elevated privileges.

Although this vulnerability is over a decade old, it remains highly relevant in cybersecurity education due to how clearly it demonstrates the risks of insecure configuration combined with unsanitized input handling.

This lab walkthrough documents the identification, exploitation, and confirmation of CVE-2007-2447 in a controlled environment.

Vulnerability Summary

• CVE ID: CVE-2007-2447

• Affected Software: Samba 3.0.0 – 3.0.25rc3

• Attack Vector: Network (SMB / TCP 139, 445)

• Impact: Remote Code Execution (RCE)

• Authentication Required: No

• Privileges Gained: Root

The vulnerability allows specially crafted SMB authentication requests to execute shell commands due to unsafe handling of the username map script directive.

Lab Environment

• Attacker Machine: Kali Linux (Metasploit Framework)

• Target Machine: Intentionally vulnerable Linux system running Samba

• Network Type: Isolated internal lab network

All testing was conducted in a controlled environment for educational and research purposes only.

Step 1: Service Discovery

Initial reconnaissance identified open SMB services on the target system:

• TCP port 139 (NetBIOS Session Service)

• TCP port 445 (Microsoft-DS / SMB)

Service version detection confirmed the target was running a legacy Samba release, placing it within the vulnerable version range.

Step 2: SMB Enumeration

Further enumeration revealed:

• Samba version in the 3.0.x branch

• Default workgroup configuration

• No authentication restrictions preventing interaction

At this stage, the target met all known preconditions for CVE-2007-2447 exploitation.

Step 3: Exploit Selection

Metasploit includes a dedicated module for this vulnerability:

exploit/multi/samba/usermap_script

This module abuses command injection through SMB authentication by leveraging the unsafe username map script configuration.

Step 4: Exploitation

After configuring the exploit with the target host and ensuring the callback address was set correctly, the exploit was executed.

Upon successful execution:

• A reverse connection was established from the target to the attacker

• A command shell session was opened automatically

Step 5: Exploit Confirmation

To confirm successful exploitation, basic post-exploitation validation was performed:

• Shell access confirmed

• Privilege level verified using standard system commands

• Access level confirmed as root

This conclusively demonstrated full remote code execution with maximum privileges.

Impact Assessment

A successful exploit of CVE-2007-2447 allows an unauthenticated remote attacker to:

• Execute arbitrary commands

• Gain full administrative control

• Pivot laterally within a network

• Establish persistence or exfiltrate data

In real-world environments, exploitation of this vulnerability would represent a complete system compromise.

Mitigation & Prevention

Although modern Samba versions are not affected, this vulnerability highlights key defensive lessons:

• Keep services patched and up to date

• Avoid dangerous legacy features

• Disable SMB where not required

• Restrict internal network exposure

• Monitor SMB traffic for abnormal authentication behavior

Defense-in-depth remains critical even when individual vulnerabilities appear outdated.

Key Takeaways

• Legacy services remain a major risk in unmanaged environments

• Configuration flaws can be just as dangerous as software bugs

• Proper enumeration is essential before exploitation

• Validation is as important as exploitation itself

CVE-2007-2447 remains a classic example of how small configuration decisions can lead to full system compromise.