Source: cve@mitre.org
The ELF loader in Linux kernel 2.4 before 2.4.25 allows local users to cause a denial of service (crash) via a crafted ELF file with an interpreter with an invalid arch (architecture), which triggers a BUG() when an invalid VMA is unmapped.
Local privilege escalation is possible on vulnerable Linux systems due to a flaw in the ELF loader. A specially crafted ELF file with an invalid architecture can trigger a kernel panic, leading to a denial-of-service (DoS) condition, potentially allowing attackers to disrupt critical systems.
Step 1: Payload Creation: An attacker crafts a malicious ELF file. This file includes a valid program section but specifies an interpreter with an invalid architecture (e.g., an architecture that doesn't exist or is not supported by the kernel).
Step 2: Payload Delivery: The attacker places the crafted ELF file on the target system. This could be achieved through various means, such as uploading it or tricking a user to execute it.
Step 3: File Execution: The attacker executes the crafted ELF file. This triggers the kernel's ELF loader.
Step 4: Interpreter Loading: The ELF loader attempts to load the specified interpreter. Due to the invalid architecture, the loader proceeds with incorrect memory management.
Step 5: Kernel Panic: The invalid architecture triggers a BUG() call within the kernel's memory management routines when trying to unmap an invalid VMA, leading to a kernel panic and system crash.
The vulnerability stems from a flaw in the Linux kernel's ELF loader, specifically within the handling of interpreter entries in ELF files. When an ELF file with an interpreter specifying an invalid architecture is loaded, the kernel attempts to unmap an invalid Virtual Memory Area (VMA). This action triggers a BUG() call, which results in a kernel panic and system crash. The root cause is a lack of proper validation of the architecture specified in the ELF interpreter, leading to an attempt to operate on an invalid memory region. This is a classic example of insufficient input validation, allowing a crafted input to cause an unexpected program state and crash.
Due to the age of the vulnerability, it's unlikely to be actively targeted by sophisticated APTs. However, it's a prime candidate for exploitation by less skilled attackers or in automated vulnerability scanners. CISA KEV status: Not Listed
Monitor system logs for kernel panics and crash dumps. Analyze the crash dumps for clues about the triggering process and the nature of the ELF file.
Examine system logs for suspicious file executions, especially of ELF files, that coincide with system crashes.
Use file integrity monitoring tools to detect the presence of unexpected or modified ELF files.
Network monitoring for unusual file transfers or access patterns that could indicate the delivery of a malicious ELF file.
Apply the latest security patches for the Linux kernel. Ensure that the kernel is updated to a version that addresses CVE-2004-0138.
Implement a robust file integrity monitoring system to detect unauthorized modifications to system files.
Restrict the execution of untrusted ELF files. This can be achieved through security policies or sandboxing techniques.
Regularly audit system logs for suspicious activity and potential exploitation attempts.
Consider using a kernel hardening module like grsecurity or PaX, which may provide additional protection against memory corruption vulnerabilities.