CVE-2023-3347 identifies a vulnerability in the SMB2 packet signing implementation within Samba on Red Hat Enterprise Linux 8. SMB2 packet signing is designed to ensure the integrity and authenticity of SMB messages exchanged between clients and servers. However, this vulnerability stems from improper enforcement of SMB2 packet signing under specific conditions: when an administrator configures the server with 'server signing = required' or when SMB2 connections are made to Domain Controllers where signing is mandatory. In these scenarios, the SMB2 packet signing mechanism can be bypassed or not properly verified, allowing an attacker positioned as a man-in-the-middle to intercept and alter SMB2 packets without detection. This compromises the integrity of the data transmitted over SMB2, potentially enabling malicious modifications to file shares or other SMB-based communications. The vulnerability does not affect confidentiality or availability directly but undermines trust in the integrity of SMB communications. Exploitation requires network access to the SMB service but does not require authentication or user interaction, increasing the attack surface. The CVSS v3.1 score of 5.9 reflects a medium severity, considering the attack vector is network-based with high attack complexity and no privileges required. No public exploits or active exploitation have been reported to date. The vulnerability is classified under CWE-924, which relates to improper verification of cryptographic signatures. Mitigation will rely on patching Samba or Red Hat Enterprise Linux 8 once fixes are released and reviewing SMB signing policies to ensure enforcement is effective.

For European organizations, this vulnerability poses a significant risk to the integrity of SMB communications, particularly in environments where Samba servers running on Red Hat Enterprise Linux 8 are used to provide file sharing or domain controller services. Man-in-the-middle attacks could allow adversaries to alter files or commands transmitted over SMB, potentially leading to data corruption, unauthorized changes, or disruption of business processes relying on SMB shares. This is especially critical for enterprises integrating Samba with Active Directory Domain Controllers, as compromised SMB integrity could affect authentication and authorization workflows. While confidentiality and availability are not directly impacted, the integrity breach can undermine trust in critical data and systems. Organizations in sectors such as finance, government, healthcare, and manufacturing, which heavily rely on secure file sharing and domain services, may face operational and compliance risks. The medium severity rating suggests that while exploitation is not trivial, the potential impact on data integrity warrants prompt attention. The absence of known exploits in the wild reduces immediate risk but should not lead to complacency.

1. Monitor Red Hat and Samba vendor advisories closely and apply security patches or updates as soon as they become available to address CVE-2023-3347. 2. Review and audit SMB signing configurations on all Samba servers, ensuring that 'server signing = required' is correctly enforced and that SMB2 packet signing cannot be bypassed. 3. For environments using Domain Controllers, verify that SMB2 packet signing is properly mandated and enforced on all SMB connections. 4. Employ network segmentation and monitoring to detect unusual SMB traffic patterns that could indicate man-in-the-middle attempts. 5. Use network-level protections such as IPsec or VPNs to secure SMB traffic and reduce exposure to interception. 6. Conduct regular security assessments and penetration tests focusing on SMB services to identify potential weaknesses. 7. Educate system administrators about the risks of improper SMB signing configurations and the importance of timely patching. 8. Consider deploying intrusion detection/prevention systems capable of analyzing SMB traffic integrity. 9. Maintain robust logging and alerting on SMB server activities to facilitate rapid incident response if exploitation is suspected.