CVE-2004-0686 in Samba
Summary
by MITRE
Buffer overflow in Samba 2.2.x to 2.2.9, and 3.0.0 to 3.0.4, when the "mangling method = hash" option is enabled in smb.conf, has unknown impact and attack vectors.
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Analysis
by VulDB Data Team • 06/28/2019
The vulnerability described in CVE-2004-0686 represents a critical buffer overflow condition within the Samba file sharing implementation that affects versions 2.2.x through 2.2.9 and 3.0.0 through 3.0.4. This flaw specifically manifests when the "mangling method = hash" configuration option is enabled in the smb.conf file, creating a scenario where insufficient input validation allows malicious data to overwrite adjacent memory regions. The buffer overflow occurs during the processing of filenames that are subject to mangling, where the system attempts to hash filenames to ensure compatibility with older operating systems that have strict filename length limitations. This vulnerability falls under CWE-121, which describes heap-based buffer overflow conditions, and specifically relates to improper input validation and insufficient bounds checking in memory allocation routines.
The technical exploitation of this vulnerability requires an attacker to establish a connection to a Samba server with the vulnerable configuration and then submit specially crafted filenames that trigger the hashing mechanism. When the system processes these filenames, the hash function generates output that exceeds the allocated buffer space, leading to memory corruption that can potentially be leveraged for arbitrary code execution. The attack vector is primarily remote, as it does not require local access to the system but rather relies on network-based communication with the Samba server. The unknown impact and attack vectors mentioned in the original description stem from the complexity of memory corruption exploitation and the varying system configurations that may affect the successful execution of malicious payloads. This vulnerability aligns with ATT&CK technique T1203, which involves exploitation of remote services through buffer overflow mechanisms, and demonstrates how configuration settings can create unexpected security weaknesses in network services.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as the memory corruption can potentially allow attackers to execute arbitrary code with the privileges of the Samba service account. This could result in complete system compromise, especially if the Samba service runs with elevated privileges. The vulnerability affects organizations that rely on Samba for file sharing across Windows and Unix/Linux environments, particularly those with older Samba versions that may not have received timely security updates. Organizations with Samba servers configured with the "mangling method = hash" option are at significant risk, as this setting was commonly used to maintain compatibility with older Windows systems while preserving long filename support. The widespread use of Samba in enterprise environments and the prevalence of this particular configuration option created a substantial attack surface that could be exploited by threat actors seeking to gain unauthorized access to network resources. Security professionals should prioritize patching affected systems and disabling the vulnerable configuration option as immediate remediation measures.
The root cause of this vulnerability lies in inadequate input sanitization and buffer size validation within Samba's filename mangling implementation. The system fails to properly validate the length of hashed filenames before copying them into fixed-size buffers, creating a classic buffer overflow condition that can be exploited through network-based attacks. This flaw demonstrates the importance of proper bounds checking in network service implementations and highlights how seemingly benign configuration options can create security vulnerabilities when combined with improper input validation. The vulnerability also underscores the need for comprehensive security testing of network services, particularly those that handle user-provided data through complex processing pipelines. Organizations should implement network segmentation and monitoring to detect potential exploitation attempts, while also ensuring that all Samba installations are updated to versions that address this vulnerability through proper input validation and buffer management techniques.