CVE-2018-10923 in glusterfs Server
Summary
by MITRE
It was found that the "mknod" call derived from mknod(2) can create files pointing to devices on a glusterfs server node. An authenticated attacker could use this to create an arbitrary device and read data from any device attached to the glusterfs server node.
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Analysis
by VulDB Data Team • 05/07/2023
The vulnerability identified as CVE-2018-10923 represents a critical security flaw in the glusterfs distributed file system implementation that stems from improper handling of device node creation through the mknod system call. This issue exists within the kernel-level file system operations where the mknod(2) system call allows for the creation of special device files, but fails to properly validate or restrict the paths to which these device nodes can point within the glusterfs environment.
The technical flaw manifests when an authenticated user with access to a glusterfs mount point can exploit the mknod system call to create device nodes that reference physical devices on the server node where the glusterfs service is running. This occurs because the implementation lacks proper validation mechanisms to prevent the creation of device nodes that point to arbitrary system devices, effectively bypassing the normal security boundaries that should protect system-level hardware interfaces. The vulnerability is classified under CWE-264 due to inadequate permissions and access control mechanisms, allowing unauthorized device access through legitimate file system operations.
The operational impact of this vulnerability is severe as it enables a remote authenticated attacker to gain access to any device node accessible to the glusterfs server process, potentially including critical system devices such as /dev/sda, /dev/null, or other hardware interfaces. This creates a privilege escalation vector where an attacker can read sensitive data from system devices, potentially extracting system information, accessing encrypted volumes, or even performing destructive operations on storage devices. The attack can be executed without requiring root privileges on the client side, making it particularly dangerous in multi-tenant environments where different users share the same glusterfs infrastructure.
The exploitation of this vulnerability aligns with techniques described in the ATT&CK framework under the T1059.003 sub-technique for command and scripting interpreter, as attackers can leverage the device access to execute reconnaissance or data exfiltration operations. Additionally, this vulnerability maps to T1078.004 for valid accounts, since it requires only authenticated access to the glusterfs service to exploit the flaw. Organizations using glusterfs deployments are particularly vulnerable if they do not implement proper access controls or if they grant unnecessary privileges to users who might exploit this flaw to access system devices.
Mitigation strategies should focus on implementing strict access controls and permissions within the glusterfs configuration, ensuring that device nodes cannot be created through the mknod system call on the server side. System administrators should disable the ability to create device nodes in glusterfs mount points by configuring appropriate security policies and restricting the capabilities of the glusterfs processes. Additionally, network segmentation and proper user authentication controls should be implemented to limit access to glusterfs services to only authorized personnel. The vulnerability can be addressed through software updates that properly validate device node creation paths and implement proper access control checks before allowing device node creation operations to proceed.