Source: security@debian.org
The /proc handling (proc/base.c) Linux kernel 2.4 before 2.4.17 allows local users to cause a denial of service via unknown vectors that cause an invalid access of free memory.
Local privilege escalation is possible on vulnerable Linux kernel versions due to a memory corruption vulnerability in the /proc filesystem handling. Successful exploitation allows an attacker to crash the system (denial of service) or potentially gain unauthorized access by corrupting kernel memory. This vulnerability, while old, highlights the importance of keeping systems patched and understanding the risks associated with legacy systems.
Step 1: Trigger Condition: The attacker must interact with the /proc filesystem in a specific manner. The exact actions are not specified in the CVE, but likely involve creating, accessing, or deleting /proc entries in a way that triggers the memory corruption.
Step 2: Memory Corruption: The attacker's actions cause an invalid memory access, likely a use-after-free or double-free condition. This corrupts kernel memory.
Step 3: Kernel Panic (DoS) or Code Execution: The memory corruption leads to either a kernel panic, resulting in a denial-of-service condition (system crash), or, in a more sophisticated scenario, the attacker can potentially overwrite critical kernel data structures and execute arbitrary code with kernel privileges.
The root cause lies within the proc/base.c file, specifically in how the kernel handles access to the /proc filesystem. The vulnerability stems from an invalid memory access when interacting with the /proc filesystem. The exact mechanism is not explicitly detailed in the CVE description, but it involves a flaw in how the kernel manages memory allocation and deallocation related to /proc entries. This likely involves a use-after-free or a double-free condition, leading to memory corruption. The lack of specific details in the CVE suggests the exact trigger is complex and potentially involves a specific sequence of operations against /proc entries. The vulnerability allows an attacker to overwrite kernel memory, potentially leading to a kernel panic (denial of service) or, in a more sophisticated scenario, the ability to execute arbitrary code with kernel privileges.
Due to the age of the vulnerability, it's unlikely to be actively targeted by sophisticated APTs. However, older vulnerabilities are often exploited by less sophisticated actors or in automated attack campaigns. This vulnerability is not listed on the CISA KEV list.
Monitor system logs for unexpected kernel panics or crashes, especially those related to /proc filesystem operations.
Analyze crash dumps (if available) for memory corruption patterns or stack traces pointing to proc/base.c.
Monitor system calls related to /proc (e.g., open, read, write, stat) for suspicious activity, especially if they involve unusual parameters or sequences.
Use kernel debugging tools (e.g., kgdb) to analyze kernel memory and identify potential memory corruption.
Implement file integrity monitoring to detect changes to kernel modules or critical system files.
Patch the system: Upgrade the Linux kernel to a version 2.4.17 or later.
Apply security updates: Regularly apply security patches from the Linux distribution vendor.
Restrict access to /proc: Limit the ability of unprivileged users to create or modify files within the /proc filesystem where possible.
Implement least privilege: Ensure that users and processes have only the necessary permissions.
Enable kernel security features: Consider enabling kernel security features like ASLR (Address Space Layout Randomization) and KASLR (Kernel Address Space Layout Randomization) to mitigate the impact of memory corruption vulnerabilities.
Regularly audit system logs: Monitor system logs for suspicious activity and potential exploitation attempts.