CVE-2015-5299 in Samba
Summary
by MITRE
The shadow_copy2_get_shadow_copy_data function in modules/vfs_shadow_copy2.c in Samba 3.x and 4.x before 4.1.22, 4.2.x before 4.2.7, and 4.3.x before 4.3.3 does not verify that the DIRECTORY_LIST access right has been granted, which allows remote attackers to access snapshots by visiting a shadow copy directory.
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Analysis
by VulDB Data Team • 07/01/2022
The vulnerability described in CVE-2015-5299 represents a critical access control flaw within the Samba file sharing implementation that affects multiple versions of the Samba server software. This issue resides in the shadow_copy2 VFS module, which is responsible for handling Windows shadow copy functionality that allows users to access previous versions of files stored on network shares. The vulnerability specifically impacts Samba versions 3.x and 4.x, with affected releases including versions prior to 4.1.22, 4.2.7, and 4.3.3, making it a long-standing issue that affected a substantial portion of Samba deployments in enterprise environments.
The technical flaw manifests in the shadow_copy2_get_shadow_copy_data function where the implementation fails to properly validate access permissions before allowing directory listing operations. This function is designed to retrieve shadow copy data from network shares, but due to the missing DIRECTORY_LIST access right verification, remote attackers can bypass normal access controls and enumerate shadow copy directories without proper authorization. The vulnerability essentially allows unauthorized access to file system snapshots that should only be accessible to users with appropriate permissions, effectively creating a backdoor for information disclosure attacks.
From an operational perspective, this vulnerability poses significant risks to organizations relying on Samba for file sharing services, particularly those implementing shadow copy functionality for backup and recovery purposes. Attackers can exploit this weakness to gain access to historical file versions that may contain sensitive information, passwords, or confidential business data that was previously thought to be protected. The impact extends beyond simple information disclosure as these snapshots often contain complete file histories, potentially exposing years of data modifications and system states that could be leveraged for further attacks. This vulnerability directly violates the principle of least privilege and can lead to comprehensive data breaches when combined with other reconnaissance activities.
Organizations affected by this vulnerability should immediately implement mitigations including updating to patched versions of Samba that address the access control validation issue, reviewing and strengthening access control policies for shadow copy functionality, and implementing network segmentation to limit exposure of Samba services to untrusted networks. The vulnerability aligns with CWE-284, which specifically addresses improper access control, and can be categorized under ATT&CK technique T1005 for data from local system and T1041 for data compression. Security teams should also consider implementing network monitoring to detect unusual directory listing activities and establish proper audit trails for shadow copy access attempts. Additionally, organizations should conduct comprehensive vulnerability assessments to identify any other potential access control weaknesses in their file sharing infrastructure and ensure that all Samba components are running patched versions to prevent exploitation of this and similar vulnerabilities.