CVE-2017-12163 in Samba
Summary
by MITRE
An information leak flaw was found in the way SMB1 protocol was implemented by Samba before 4.4.16, 4.5.x before 4.5.14, and 4.6.x before 4.6.8. A malicious client could use this flaw to dump server memory contents to a file on the samba share or to a shared printer, though the exact area of server memory cannot be controlled by the attacker.
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Analysis
by VulDB Data Team • 12/30/2022
The vulnerability identified as CVE-2017-12163 represents a critical information disclosure flaw within the Samba implementation of the SMB1 protocol. This vulnerability affects multiple versions of the Samba software suite, specifically targeting releases prior to 4.4.16, 4.5.14, and 4.6.8 across their respective version branches. The flaw stems from improper handling of certain SMB1 protocol requests that allows unauthorized access to server memory contents through the samba file sharing mechanism. The vulnerability operates at the protocol implementation level where the samba server fails to properly validate or sanitize memory access requests, creating an unintended information leakage channel that can be exploited by malicious actors.
The technical nature of this vulnerability falls under CWE-200, which describes "Information Exposure" in software systems. The flaw manifests when a malicious client establishes an SMB1 connection to a vulnerable samba server and crafts specific requests that trigger memory dumping functionality. This occurs because the samba implementation does not adequately restrict memory access patterns or validate the scope of memory regions that can be read through the shared file system or printer sharing mechanisms. The attacker can leverage this weakness to write memory contents to files on the samba share or to shared printers, effectively creating a memory dump that reveals sensitive information stored in server memory. While the attacker cannot precisely control which memory regions are exposed, the sheer volume of information that can be leaked includes potentially sensitive data such as authentication tokens, session information, and other memory-resident data that could be valuable to an attacker.
From an operational impact perspective, this vulnerability presents a significant risk to organizations relying on samba servers for file sharing and printer services. The information leakage could expose credentials, session keys, or other sensitive data that might be stored in memory, potentially leading to further compromise of the system. Attackers could use the leaked information to conduct credential reuse attacks, escalate privileges, or launch more sophisticated exploitation attempts against the compromised system. The vulnerability is particularly concerning because it affects the core file sharing functionality of samba servers, which are commonly used in enterprise environments, home networks, and various network infrastructure components. The attack vector requires only network access to the vulnerable samba server, making it relatively easy to exploit and potentially affecting a wide range of systems that have not been updated to patched versions.
The mitigation strategy for CVE-2017-12163 primarily involves upgrading to patched versions of samba software that address the memory handling issues in the SMB1 protocol implementation. Organizations should prioritize updating their samba servers to versions 4.4.16, 4.5.14, or 4.6.8, depending on their current deployment. Additionally, network administrators should consider disabling SMB1 protocol support entirely, as it represents a legacy protocol with known security weaknesses and is no longer recommended for use in modern network environments. The disablement of SMB1 aligns with Microsoft's recommendations and the broader security community's stance on phasing out legacy protocols that lack modern security features. Security monitoring should also be enhanced to detect unusual file creation patterns or memory-related activities on samba shares, as these could indicate exploitation attempts. The vulnerability also highlights the importance of maintaining up-to-date security patches and implementing proper network segmentation to limit the potential impact of such information disclosure vulnerabilities.