CVE-2015-0240 in Samba
Summary
by MITRE
The Netlogon server implementation in smbd in Samba 3.5.x and 3.6.x before 3.6.25, 4.0.x before 4.0.25, 4.1.x before 4.1.17, and 4.2.x before 4.2.0rc5 performs a free operation on an uninitialized stack pointer, which allows remote attackers to execute arbitrary code via crafted Netlogon packets that use the ServerPasswordSet RPC API, as demonstrated by packets reaching the _netr_ServerPasswordSet function in rpc_server/netlogon/srv_netlog_nt.c.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/09/2025
The vulnerability described in CVE-2015-0240 represents a critical heap-based buffer overflow in the Netlogon server implementation within Samba's smbd service. This flaw exists in multiple Samba versions including 3.5.x and 3.6.x before 3.6.25, 4.0.x before 4.0.25, 4.1.x before 4.1.17, and 4.2.x before 4.2.0rc5, making it a widespread issue affecting enterprise network authentication systems. The vulnerability specifically manifests when processing crafted Netlogon packets through the ServerPasswordSet RPC API, which is a fundamental component of Samba's network authentication infrastructure.
The technical root cause of this vulnerability lies in an improper memory management operation where the Netlogon server performs a free operation on an uninitialized stack pointer during the processing of the _netr_ServerPasswordSet function. This function resides in rpc_server/netlogon/srv_netlog_nt.c and handles authentication requests from clients attempting to set or update passwords through the Netlogon protocol. The uninitialized stack pointer creates a scenario where memory deallocation occurs at an unpredictable memory location, leading to a heap corruption condition that can be exploited by remote attackers to execute arbitrary code with the privileges of the smbd process. This vulnerability maps directly to CWE-459, which describes improper cleanup of resources, and CWE-122, which covers heap-based buffer overflow conditions.
The operational impact of CVE-2015-0240 is severe and potentially catastrophic for affected organizations. Remote attackers can exploit this vulnerability without authentication, making it particularly dangerous in networked environments where Samba servers are exposed to untrusted networks. Successful exploitation allows attackers to gain arbitrary code execution on the target system, potentially leading to complete system compromise and lateral movement within the network. The vulnerability affects the core authentication infrastructure, meaning that attackers who successfully exploit it can potentially impersonate legitimate users, access sensitive network resources, and establish persistent access to the compromised system. This aligns with ATT&CK technique T1078 which covers valid accounts and T1566 which covers credential harvesting through network protocols.
Organizations should implement immediate mitigations including applying the vendor-provided patches for all affected Samba versions, implementing network segmentation to limit access to Samba servers, and monitoring for suspicious Netlogon traffic patterns. The patch addresses the uninitialized pointer issue by ensuring proper memory initialization before any free operations are performed. Additionally, administrators should consider disabling unnecessary Netlogon services and implementing network access controls to restrict which systems can communicate with Samba servers. Organizations should also conduct thorough vulnerability assessments to identify all systems running affected Samba versions and ensure that proper network monitoring is in place to detect exploitation attempts. The vulnerability demonstrates the critical importance of proper memory management in network services and highlights the need for comprehensive security testing of authentication protocols, particularly those handling sensitive credential information.