CVE-2010-2248 in Linux
Summary
by MITRE
fs/cifs/cifssmb.c in the CIFS implementation in the Linux kernel before 2.6.34-rc4 allows remote attackers to cause a denial of service (panic) via an SMB response packet with an invalid CountHigh value, as demonstrated by a response from an OS/2 server, related to the CIFSSMBWrite and CIFSSMBWrite2 functions.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability described in CVE-2010-2248 represents a critical denial of service flaw within the Common Internet File System implementation of the Linux kernel. This issue affects versions prior to 2.6.34-rc4 and specifically targets the fs/cifs/cifssmb.c file which handles SMB protocol communications. The vulnerability arises from insufficient input validation when processing SMB response packets, creating a condition where maliciously crafted packets can trigger system instability. The flaw is particularly concerning because it can be exploited remotely, allowing attackers to cause kernel panics that result in complete system downtime. The vulnerability was demonstrated against OS/2 servers, indicating that the issue stems from how the Linux CIFS client handles responses from certain server implementations that use invalid CountHigh values in their SMB protocol exchanges.
The technical root cause of this vulnerability lies in the improper validation of CountHigh field values within SMB response packets processed by the CIFSSMBWrite and CIFSSMBWrite2 functions. When these functions receive a response packet containing an invalid CountHigh value, the kernel fails to properly validate the input before proceeding with operations that depend on this field. This lack of validation leads to unpredictable behavior where the kernel attempts to process data structures using invalid parameters, ultimately resulting in a kernel panic. The vulnerability operates at the kernel level and leverages the CIFS protocol implementation to execute the attack, making it particularly dangerous as it can affect any system running an affected kernel version and mounting CIFS shares. The flaw is classified as a buffer overflow condition in the context of kernel memory management, where invalid data processing leads to system termination.
The operational impact of this vulnerability extends beyond simple denial of service, as it can result in complete system crashes and require manual intervention for recovery. Systems utilizing CIFS mounts are particularly at risk since the vulnerability can be triggered by any legitimate SMB response from a compromised or misconfigured server. The attack vector requires no authentication and can be executed from remote locations, making it a significant threat to networked environments. Organizations that rely on CIFS file sharing for business operations face potential operational disruptions when this vulnerability is exploited, as the resulting kernel panics can lead to extended downtime and data accessibility issues. The vulnerability also impacts system reliability and availability, as it can be triggered by legitimate network traffic without any malicious intent from the end user.
Mitigation strategies for CVE-2010-2248 primarily involve updating to kernel versions 2.6.34-rc4 or later where the vulnerability has been patched. System administrators should prioritize patching affected systems and monitor for any exploitation attempts in their network traffic. The patch addresses the validation issue by implementing proper bounds checking on CountHigh values before processing SMB response packets. Organizations should also consider implementing network segmentation to limit exposure and monitor SMB traffic for anomalous patterns that might indicate exploitation attempts. Additionally, disabling CIFS mounts when not actively needed can reduce the attack surface. This vulnerability aligns with CWE-129, which describes improper validation of input ranges, and maps to ATT&CK technique T1499.004 for denial of service attacks. The vulnerability demonstrates the importance of robust input validation in kernel space code and highlights the critical nature of timely security updates in maintaining system integrity and availability.