CVE-2015-5370 in Samba
Summary
by MITRE
Samba 3.x and 4.x before 4.2.11, 4.3.x before 4.3.8, and 4.4.x before 4.4.2 does not properly implement the DCE-RPC layer, which allows remote attackers to perform protocol-downgrade attacks, cause a denial of service (application crash or CPU consumption), or possibly execute arbitrary code on a client system via unspecified vectors.
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Analysis
by VulDB Data Team • 07/24/2022
The vulnerability identified as CVE-2015-5370 represents a critical flaw in the Samba implementation of the Distributed Computing Environment Remote Procedure Call (DCE-RPC) protocol across multiple versions of the Samba software. This weakness specifically affects Samba 3.x and 4.x versions prior to the mentioned patches, creating a significant security risk for systems relying on Samba for file sharing and network services. The vulnerability stems from improper implementation of the DCE-RPC layer, which forms a crucial component of Samba's network communication infrastructure. DCE-RPC is a standard protocol used for distributed computing that enables programs to execute procedures on remote systems as if they were local operations, making it fundamental to Samba's functionality in networked environments.
The technical flaw manifests in the protocol-downgrade attack capability that allows remote adversaries to manipulate the communication layer between Samba servers and clients. This implementation weakness creates opportunities for attackers to force connections to use older, less secure protocol versions that may have known vulnerabilities or lack modern security features. The vulnerability's impact extends beyond simple protocol manipulation, as it can result in application crashes that lead to denial of service conditions, or potentially enable arbitrary code execution on client systems. The unspecified vectors mentioned in the description indicate that the attack surface is broad and can be exploited through various communication pathways within the Samba network stack. This type of vulnerability falls under CWE-242, which deals with the use of a function with a known security weakness, and represents a classic example of improper implementation of security protocols in network services.
The operational impact of CVE-2015-5370 is severe for organizations using affected Samba versions, as it can compromise the integrity and availability of network services. When exploited, the vulnerability can cause denial of service conditions that disrupt file sharing operations, print services, and other critical network functions that depend on Samba. The potential for arbitrary code execution on client systems creates a pathway for attackers to gain unauthorized access to endpoints, potentially escalating privileges and establishing persistent access within the network. This vulnerability directly aligns with ATT&CK technique T1071.004 for application layer protocol usage and T1499.004 for network disruption, making it a significant concern for enterprise security operations. The vulnerability's exploitation can lead to cascading failures throughout network infrastructure, particularly in environments where Samba servers serve as critical file sharing points for multiple users and applications.
Mitigation strategies for CVE-2015-5370 should prioritize immediate patch deployment for all affected Samba versions, with particular attention to systems running Samba 3.x, 4.2.x, 4.3.x, and 4.4.x before the specified patch versions. Network segmentation and firewall rules should be implemented to restrict unnecessary DCE-RPC traffic between Samba servers and clients, reducing the attack surface available to potential exploiters. Organizations should also implement monitoring for unusual network traffic patterns that might indicate protocol-downgrade attempts or other exploitation activities. Security teams should conduct comprehensive vulnerability assessments to identify all systems running affected Samba versions and prioritize remediation efforts based on risk exposure. The patching process should include thorough testing in controlled environments before deployment to production systems to ensure compatibility with existing network configurations. Additionally, implementing network-based intrusion detection systems with signatures for known exploitation patterns can provide early warning capabilities for potential attacks targeting this vulnerability.