CVE-2025-10230: Samba WINS Hook RCE Vulnerability

CVE-2025-10230 Overview

A critical command injection vulnerability has been discovered in Samba's front-end WINS hook handling mechanism. The flaw exists because NetBIOS names from registration packets are passed directly to a shell without proper validation or escaping. This allows unsanitized NetBIOS name data from WINS registration packets to be inserted into a shell command and executed by the Samba Active Directory Domain Controller's wins hook, enabling an unauthenticated network attacker to achieve remote command execution as the Samba process.

Critical Impact

Unauthenticated attackers can execute arbitrary commands on Samba Active Directory Domain Controllers by sending maliciously crafted WINS registration packets with specially crafted NetBIOS names, potentially leading to complete system compromise.

Affected Products

• Samba Active Directory Domain Controllers with WINS hook enabled
• Samba deployments utilizing front-end WINS hook handling
• Systems running vulnerable Samba versions with WINS registration functionality

Discovery Timeline

• 2025-11-07 - CVE-2025-10230 published to NVD
• 2025-12-03 - Last updated in NVD database

Technical Details for CVE-2025-10230

Vulnerability Analysis

This vulnerability (CWE-78: Improper Neutralization of Special Elements used in an OS Command) represents a severe command injection flaw in Samba's WINS hook implementation. The core issue stems from the application's failure to properly sanitize or escape NetBIOS name data before passing it to the system shell for execution.

When a Samba Active Directory Domain Controller processes WINS registration packets, the NetBIOS names contained within these packets are directly incorporated into shell commands executed by the wins hook mechanism. An attacker can exploit this by crafting malicious NetBIOS names containing shell metacharacters or command sequences, which are then executed with the privileges of the Samba process.

The network-accessible nature of this vulnerability, combined with the absence of authentication requirements, makes it particularly dangerous in enterprise environments where Samba is commonly deployed for Active Directory services.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and improper handling of user-controlled data. Specifically, the Samba WINS hook implementation fails to sanitize or escape special shell characters in NetBIOS names before constructing and executing shell commands. This lack of input validation allows attackers to inject arbitrary shell commands through specially crafted NetBIOS registration packets.

Attack Vector

The attack is executed over the network without requiring authentication or user interaction. An attacker sends a malicious WINS registration packet containing a crafted NetBIOS name with embedded shell commands to the vulnerable Samba server. When the WINS hook processes this registration, the unsanitized NetBIOS name is passed to the shell, causing the injected commands to execute with the privileges of the Samba process.

The attack flow involves:

1. Attacker crafts a WINS registration packet with a NetBIOS name containing shell metacharacters and malicious commands
2. The packet is sent to the vulnerable Samba Active Directory Domain Controller
3. The WINS hook mechanism processes the registration and constructs a shell command incorporating the malicious NetBIOS name
4. The shell interprets the metacharacters and executes the injected commands
5. The attacker achieves remote command execution as the Samba process

Detection Methods for CVE-2025-10230

Indicators of Compromise

• Unusual WINS registration traffic containing special characters or shell metacharacters in NetBIOS names
• Unexpected child processes spawned by Samba processes (smbd, nmbd, or related daemons)
• Suspicious command execution patterns originating from the Samba service account
• Anomalous network connections initiated by Samba processes to external addresses

Detection Strategies

• Monitor WINS registration traffic for NetBIOS names containing shell metacharacters such as ;, |, $(), backticks, or &&
• Implement process monitoring to detect unexpected command execution by Samba daemon processes
• Deploy network-based intrusion detection signatures to identify malformed or suspicious WINS packets
• Review Samba logs for registration attempts with unusual or malformed NetBIOS names

Monitoring Recommendations

• Enable verbose logging for Samba WINS services to capture detailed registration information
• Implement endpoint detection and response (EDR) monitoring on systems running Samba AD Domain Controllers
• Configure network monitoring to alert on anomalous NetBIOS Name Service (NBNS) traffic patterns
• Establish baseline behavior for Samba processes and alert on deviations

How to Mitigate CVE-2025-10230

Immediate Actions Required

• Review and apply security patches from Samba when available by consulting the Samba Security History
• If WINS hook functionality is not required, disable it in the Samba configuration
• Implement network segmentation to limit exposure of Samba services to trusted networks only
• Monitor systems for signs of exploitation using the detection methods outlined above
• Review the Red Hat CVE Advisory for distribution-specific guidance

Patch Information

Consult the Samba Security History page for official patches and updated versions addressing this vulnerability. Additional details may be found in the Red Hat Bug Report for Red Hat-based distributions.

Workarounds

• Disable the WINS hook in the Samba configuration file (smb.conf) if this functionality is not required for operations
• Restrict network access to Samba WINS services using firewall rules, limiting connections to trusted IP addresses only
• Implement network-level filtering to block WINS registration packets containing suspicious characters
• Consider deploying a Web Application Firewall (WAF) or network IDS with custom rules to detect and block exploitation attempts

# Disable WINS hook in smb.conf
# Add or modify the following in /etc/samba/smb.conf
[global]
    wins hook = 
    # Alternatively, ensure wins support is disabled if not needed
    wins support = no