Samba, the widely-used open-source implementation of the SMB/CIFS networking protocol, has disclosed a critical remote code execution (RCE) vulnerability identified as CVE-2025-10230. This flaw poses a significant risk to organizations utilizing Samba as an Active Directory Domain Controller (AD DC), potentially allowing unauthenticated attackers to execute arbitrary code and compromise entire systems.
Understanding the Vulnerability
The vulnerability originates from improper validation within Samba’s Windows Internet Name Service (WINS) hook mechanism. WINS, a legacy protocol designed to resolve NetBIOS names in pre-DNS Windows networks, is largely obsolete but remains present in some configurations. In Samba, when WINS support is enabled alongside a custom ‘wins hook’ script specified in the smb.conf configuration file, the system becomes susceptible to exploitation.
An attacker can exploit this flaw by sending specially crafted WINS name registration requests containing shell metacharacters within the 15-character NetBIOS limit. These malicious inputs are then processed by the ‘wins hook’ script without proper sanitization, leading to the execution of arbitrary commands on the affected system. Notably, this attack does not require authentication, making it particularly dangerous.
Scope and Impact
This vulnerability affects all Samba versions from 4.0 onwards when configured as an Active Directory Domain Controller with both WINS support and a non-empty ‘wins hook’ parameter. Standalone or member servers, which utilize a different WINS implementation, are not impacted.
The potential consequences of this vulnerability are severe. An unauthenticated remote attacker could gain full control over the affected domain controller, leading to:
– Data Exfiltration: Access to sensitive organizational data.
– Malware Deployment: Installation of malicious software, including ransomware.
– Privilege Escalation: Elevation of privileges within the network, facilitating further attacks.
Given the critical nature of domain controllers in managing network security and authentication, exploiting this vulnerability could have widespread and devastating effects on an organization’s infrastructure.
Mitigation Strategies
In response to this vulnerability, the Samba Team has released patches addressing the issue in versions 4.23.2, 4.22.5, and 4.21.9. Administrators are strongly advised to upgrade to these patched versions immediately to secure their systems.
For environments where immediate upgrading is not feasible, the following mitigations are recommended:
1. Disable the ‘wins hook’ Parameter: Remove or comment out the ‘wins hook’ parameter in the smb.conf file.
2. Disable WINS Support: Set ‘wins support = no’ in the smb.conf file to disable WINS functionality entirely.
It’s important to note that the default configuration of Samba has WINS support disabled, which means that systems without explicit WINS configuration are not vulnerable.
Broader Implications
This vulnerability underscores the risks associated with maintaining legacy protocols and configurations within modern network environments. WINS, being an outdated protocol, offers limited utility in contemporary networks and poses unnecessary security risks.
Organizations are encouraged to:
– Audit Existing Configurations: Review and identify any legacy protocols or configurations that may introduce vulnerabilities.
– Phase Out Deprecated Services: Gradually eliminate the use of obsolete services like WINS to reduce the attack surface.
– Implement Robust Security Practices: Regularly update and patch systems, conduct security assessments, and adopt a proactive approach to network security.
By addressing these areas, organizations can enhance their security posture and mitigate the risks associated with similar vulnerabilities in the future.
Conclusion
The disclosure of CVE-2025-10230 serves as a critical reminder of the importance of maintaining up-to-date systems and configurations. Administrators must act swiftly to apply the necessary patches or mitigations to protect their networks from potential exploitation. Furthermore, this incident highlights the need for continuous evaluation and modernization of network protocols to ensure a secure and resilient infrastructure.
