Source: cve@mitre.org
Multiple integer overflows in the 32bit emulation for AMD64 architectures in Linux 2.4 kernel before 2.4.21 allows attackers to cause a denial of service or gain root privileges via unspecified vectors that trigger copy_from_user function calls with improper length arguments.
Critical vulnerability in older Linux kernels (2.4.x) allows for privilege escalation and denial-of-service attacks. Exploiting integer overflows within the AMD64 32-bit emulation, attackers can manipulate memory copy operations to overwrite critical kernel data, leading to system compromise or instability.
Step 1: Triggering the Vulnerability: The attacker crafts a malicious 32-bit application or leverages an existing 32-bit application on a vulnerable system. This application is designed to interact with the kernel through system calls that utilize copy_from_user or similar memory copy functions.
Step 2: Crafting Malicious Input: The attacker provides specially crafted input to the application. This input includes size parameters designed to cause an integer overflow when processed by the kernel's 32-bit emulation code.
Step 3: Integer Overflow: The kernel's 32-bit emulation layer processes the input, and the size parameters are used in calculations. Due to the lack of proper validation, the size calculation overflows, resulting in a small or negative value.
Step 4: Memory Corruption: The overflowed size is then used in a memory copy operation (e.g., copy_from_user). Because of the incorrect size, the copy operation either writes beyond the intended buffer (buffer overflow) or writes to an unintended memory location.
Step 5: Privilege Escalation/DoS: Depending on the overwritten memory, the attacker can achieve either privilege escalation (by overwriting kernel data structures) or a denial-of-service (by corrupting critical kernel memory, leading to a system crash).
The vulnerability stems from multiple integer overflows within the 32-bit emulation layer of the Linux 2.4 kernel, specifically in the handling of memory copy operations (e.g., copy_from_user). The 32-bit emulation code, designed to allow 32-bit applications to run on 64-bit AMD64 architectures, fails to properly validate the size arguments passed to these copy functions. This leads to an integer overflow when calculating the size of the memory region to be copied. When the overflow occurs, the calculated size wraps around to a small, potentially negative, value. This incorrect size is then used in subsequent memory operations. This can lead to a buffer overflow or out-of-bounds write when copying data from user space to kernel space. By crafting malicious input with specific size parameters, an attacker can overwrite kernel memory, potentially corrupting critical data structures, hijacking control flow, or gaining root privileges. The root cause is a lack of proper input validation on the size parameters passed to copy_from_user and related functions within the 32-bit emulation layer. This allows for manipulation of memory copy operations, leading to memory corruption and potential code execution.
While no specific APTs are directly linked to this CVE, the nature of the vulnerability (privilege escalation) makes it attractive to any threat actor seeking to gain control of a system. The age of the vulnerability makes it less likely to be targeted by sophisticated actors. Not listed on CISA KEV.
Monitor system call activity, specifically calls to copy_from_user and related functions within the 32-bit emulation layer.
Analyze system logs for unexpected kernel panics or crashes, especially on systems running 32-bit applications.
Implement intrusion detection rules to identify suspicious memory write operations or attempts to overwrite kernel memory.
Monitor for unusual process behavior or memory access patterns that might indicate exploitation.
Examine core dumps for signs of memory corruption, such as overwritten data structures or corrupted code pointers.
Upgrade to a patched Linux kernel version (2.4.21 or later).
Apply security patches provided by the Linux distribution vendor.
Isolate or remove vulnerable systems from the network.
Implement a robust intrusion detection and prevention system (IDPS).
Regularly audit system configurations and security settings.
Implement least privilege principles, limiting the access rights of users and processes.
Consider using kernel hardening techniques, such as address space layout randomization (ASLR) and data execution prevention (DEP), if available on the target system.