CVE-2023-1194 in Linux
Summary
by MITRE • 11/03/2023
An out-of-bounds (OOB) memory read flaw was found in parse_lease_state in the KSMBD implementation of the in-kernel samba server and CIFS in the Linux kernel. When an attacker sends the CREATE command with a malformed payload to KSMBD, due to a missing check of `NameOffset` in the `parse_lease_state()` function, the `create_context` object can access invalid memory.
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Analysis
by VulDB Data Team • 08/21/2024
The vulnerability identified as CVE-2023-1194 represents a critical out-of-bounds memory read flaw within the KSMBD implementation of the Linux kernel's CIFS server functionality. This issue resides in the parse_lease_state function where insufficient validation of the NameOffset parameter creates a pathway for attackers to exploit memory access violations. The vulnerability specifically manifests when the KSMBD server processes CREATE commands with malformed payloads, exploiting a fundamental lack of input sanitization that allows arbitrary memory access patterns to be executed through carefully crafted network requests.
The technical implementation of this flaw demonstrates a classic buffer over-read condition that aligns with CWE-125, which describes out-of-bounds read vulnerabilities in software implementations. The parse_lease_state function fails to properly validate the NameOffset field within the create_context object structure, enabling attackers to manipulate memory access pointers that should be constrained by proper boundary checks. This particular implementation flaw affects the in-kernel samba server and CIFS subsystem, making it particularly dangerous as it operates at the kernel level where memory corruption can lead to privilege escalation and system compromise. The vulnerability's exploitation requires network access to the target system and can be executed through standard SMB protocol communication channels.
From an operational impact perspective, this vulnerability presents significant security risks to systems running kernel versions that include the affected KSMBD implementation. Attackers can leverage this flaw to perform memory enumeration attacks, potentially extracting sensitive information from kernel memory spaces, or to establish persistent access patterns that could lead to full system compromise. The vulnerability's exploitation capability aligns with ATT&CK technique T1059.001 for command and script injection, as successful exploitation could enable attackers to execute arbitrary code within the kernel context. Organizations running affected kernel versions face potential data breaches, system instability, and complete loss of system control if this vulnerability is exploited in the wild.
Mitigation strategies for CVE-2023-1194 must prioritize immediate patching of affected kernel versions, as the vulnerability exists at the core kernel level where traditional user-space protections cannot prevent exploitation. System administrators should implement network segmentation to limit access to CIFS/SMB services, particularly on systems where the vulnerable KSMBD implementation is active. The recommended approach includes deploying kernel updates that address the missing NameOffset validation in parse_lease_state, combined with network monitoring to detect anomalous CREATE command patterns that may indicate exploitation attempts. Additionally, implementing proper input validation controls at the application level and monitoring for memory access violations can help detect potential exploitation attempts. Organizations should also consider disabling unnecessary CIFS/SMB services when not required for business operations, reducing the attack surface for potential exploitation of this kernel-level vulnerability that can lead to complete system compromise through privilege escalation techniques.