Samba 3.5.0 - 4.6.4 Remote Code Execution (CVE-2017-7494)
Overview
Samba 3.5.0 - 4.6.4 Remote Code Execution, tracked as CVE-2017-7494, affects vulnerable Samba file-sharing servers. Samba provides SMB/CIFS file and printer sharing for Unix-like systems, and many deployments expose writable shares to users, services, or internal networks.
Vulnerability Overview
CVE-2017-7494 allows a malicious client to upload a shared library to a writable Samba share and then cause the Samba server process to load and execute it. The vulnerable behavior turns write access to a network share into a server-side code execution path.
The practical requirement is important: the attacker needs a way to place a shared library on a writable share that the Samba server can access. In environments with anonymous writable shares, weak credentials, broad internal write permissions, or compromised user accounts, this condition can be realistic.
Impact
CVE-2017-7494 has a CVSS 3.1 score of 9.8 and is rated Critical. The score reflects network reachability, low attack complexity, no required privileges in the generic scoring model, no user interaction, and high confidentiality, integrity, and availability impact.
Successful exploitation can allow remote code execution on the file server, unauthorized access to shared data, modification of files, deployment of malware, persistence on the host, or movement into other systems that trust the Samba server.
The vulnerability was added to the CISA Known Exploited Vulnerabilities Catalog on March 30, 2023, which reflects confirmed exploitation in the wild.
Vulnerability Scope
CVE-2017-7494 affects Samba versions from 3.5.0 onward before the fixed releases 4.6.4, 4.5.10, and 4.4.14. Samba’s advisory also recommends upgrading or applying vendor patches, and notes a configuration workaround that disables named pipe endpoint access.
The highest-risk exposure is a Samba server with writable shares reachable by untrusted or broadly privileged clients. Internal file servers can still be high impact because they often store sensitive documents and are trusted by many users and systems.
Lab Focus
This lab focuses on understanding how writable network shares can become code execution risk when server-side loading behavior is unsafe. The goal is to practice evaluating share permissions, exposed SMB services, and the difference between simple file write access and full remote code execution.