Source: cve@mitre.org
Various routines for the ppc64 architecture on Linux kernel 2.6 prior to 2.6.2 and 2.4 prior to 2.4.24 do not use the copy_from_user function when copying data from userspace to kernelspace, which crosses security boundaries and allows local users to cause a denial of service.
Critical vulnerability in older Linux kernel versions (2.4 and 2.6) on the ppc64 architecture allows local users to achieve a denial-of-service (DoS). The flaw stems from improper handling of user-supplied data, bypassing security checks and potentially leading to system instability or crashes. This vulnerability is a reminder of the importance of patching and maintaining up-to-date kernel versions.
Step 1: Triggering the Vulnerability: A local user interacts with a system call or kernel function that handles data transfer from userspace to kernelspace on a vulnerable ppc64 system.
Step 2: Crafting Malicious Input: The user crafts a malicious payload, designed to exploit the missing copy_from_user check. This payload could be a large amount of data or data specifically designed to overwrite kernel memory regions.
Step 3: Data Transfer: The crafted payload is passed to the vulnerable kernel function.
Step 4: Kernel Memory Corruption: The kernel function, lacking the copy_from_user protection, directly copies the user-supplied data into kernel memory. Due to the missing bounds checks, this can lead to a buffer overflow or other memory corruption.
Step 5: Denial of Service: The memory corruption causes the kernel to crash, resulting in a kernel panic and a denial of service. The system becomes unresponsive and requires a reboot.
The vulnerability arises from the failure to use the copy_from_user function when copying data from userspace to kernelspace in various routines within the ppc64 architecture of Linux kernel versions 2.4 and 2.6. This function is crucial for security as it performs checks to prevent unauthorized memory access. Without copy_from_user, the kernel directly trusts user-provided data, leading to potential issues. The root cause is a missing bounds check and improper data validation. Specifically, the code fails to verify the size and validity of the data being copied, allowing a malicious user to supply crafted input that can overwrite kernel memory. This can manifest as a buffer overflow or other memory corruption issues, ultimately leading to a kernel panic and a DoS.
Due to the age of the vulnerability, it is unlikely to be actively targeted by sophisticated APTs. However, it could be exploited by less sophisticated actors or automated tools. This vulnerability is not listed on the CISA KEV.
Monitor system logs for kernel panics or unexpected system reboots.
Analyze system calls related to data transfer from userspace to kernelspace, especially those involving the ppc64 architecture.
Examine kernel crash dumps for signs of memory corruption.
Use intrusion detection systems (IDS) to monitor for suspicious system call sequences.
Monitor for unusual network traffic patterns or resource exhaustion that could indicate a DoS attack.
Upgrade the Linux kernel to a version 2.6.2 or later, or 2.4.24 or later. This is the primary and most effective remediation.
If upgrading is not immediately possible, apply any available security patches or backports for the specific kernel version.
Implement strict access controls to limit user privileges and prevent unauthorized access to the system.
Regularly audit system logs for suspicious activity.
Implement a robust backup and recovery plan to minimize downtime in case of a successful exploit.