CVE-2009-2813 in Samba
Summary
by MITRE
Samba 3.4 before 3.4.2, 3.3 before 3.3.8, 3.2 before 3.2.15, and 3.0.12 through 3.0.36, as used in the SMB subsystem in Apple Mac OS X 10.5.8 when Windows File Sharing is enabled, Fedora 11, and other operating systems, does not properly handle errors in resolving pathnames, which allows remote authenticated users to bypass intended sharing restrictions, and read, create, or modify files, in certain circumstances involving user accounts that lack home directories.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/22/2021
The vulnerability described in CVE-2009-2813 represents a critical path traversal flaw within the Samba file sharing implementation that affects multiple versions of the Samba software stack. This issue specifically targets the SMB subsystem used in Apple Mac OS X 10.5.8 and various Linux distributions including Fedora 11, where Windows File Sharing functionality is enabled. The flaw stems from inadequate error handling mechanisms during pathname resolution processes, creating a scenario where authenticated remote attackers can manipulate file access controls and bypass intended sharing restrictions.
The technical root cause of this vulnerability lies in how Samba handles error conditions when processing file paths during SMB protocol operations. When user accounts lack proper home directory structures, the software fails to correctly validate or sanitize pathname components, allowing attackers to craft malicious file requests that can traverse beyond intended directory boundaries. This error handling deficiency creates a path traversal condition that enables unauthorized access to files and directories that should normally be restricted to specific users or groups. The vulnerability operates at the protocol level within the SMB subsystem, making it particularly dangerous as it can be exploited through standard network file sharing mechanisms without requiring special privileges beyond authentication.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it allows authenticated attackers to perform read, create, and modify operations on files and directories that should remain protected. This capability can lead to data exfiltration, system compromise, and potential lateral movement within networks where Samba servers are deployed. Attackers can exploit this vulnerability to access sensitive information, modify system files, or create backdoors, making it particularly dangerous in enterprise environments where file sharing is extensively used. The vulnerability affects systems where Windows File Sharing is enabled, which is common in mixed operating system environments where Mac OS X systems need to communicate with Windows-based file servers.
Security professionals should note that this vulnerability aligns with CWE-22 Path Traversal and CWE-23 Relative Path Traversal, both of which are categorized under the broader category of improper input validation flaws. The attack pattern described in this vulnerability follows the ATT&CK technique T1078 Valid Accounts, where attackers leverage legitimate authenticated accounts to exploit weaknesses in access control mechanisms. Organizations using affected Samba versions should implement immediate patches to address this vulnerability, as the flaw can be exploited remotely by authenticated users with minimal privileges. The remediation process involves upgrading to patched versions of Samba software, specifically versions 3.0.37, 3.2.15, 3.3.8, and 3.4.2 or later, which contain proper error handling for pathname resolution. Additionally, system administrators should review and tighten file sharing permissions, implement network segmentation, and monitor for suspicious file access patterns that may indicate exploitation attempts.