CVE-2003-0248 in Linux
Summary
by MITRE
The mxcsr code in Linux kernel 2.4 allows attackers to modify CPU state registers via a malformed address.
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Analysis
by VulDB Data Team • 06/25/2019
The vulnerability identified as CVE-2003-0248 represents a critical flaw in the Linux kernel version 2.4 that affects the management of CPU state registers through the mxcsr code. This issue stems from inadequate validation of address parameters within the kernel's floating-point unit handling mechanisms, creating a pathway for malicious actors to manipulate processor state registers. The vulnerability specifically targets the x87 floating-point unit and SSE (Streaming SIMD Extensions) control and status register management, where improper bounds checking allows unauthorized modifications to CPU state.
The technical exploitation of this vulnerability occurs when malformed addresses are processed through the kernel's mxcsr handling code, which is responsible for managing the floating-point control and status register. This register contains critical flags and control bits that govern floating-point operations and exception handling. Attackers can leverage this weakness to inject malicious values into the processor state, potentially leading to privilege escalation or system instability. The flaw exists in the kernel's memory management subsystem where it fails to properly validate the address space boundaries when processing floating-point operations, creating a direct attack surface that bypasses normal kernel protections.
Operationally, this vulnerability poses significant risks to systems running Linux kernel 2.4, particularly in environments where privileged operations are performed or where multiple users share system resources. The ability to modify CPU state registers can enable attackers to manipulate floating-point exception handling, alter processor behavior, or potentially gain elevated privileges. Systems utilizing the x87 floating-point unit or SSE instructions are particularly susceptible, as these components rely heavily on proper mxcsr register management. The impact extends beyond simple privilege escalation to include potential denial of service conditions where the processor state becomes corrupted, leading to system crashes or unpredictable behavior.
Mitigation strategies for CVE-2003-0248 primarily involve upgrading to newer kernel versions where this vulnerability has been addressed through proper input validation and bounds checking. System administrators should implement immediate kernel updates to patch the vulnerable mxcsr handling code and ensure that all floating-point operations are properly validated before processing. Additionally, organizations should consider implementing kernel hardening measures such as stack canaries, address space layout randomization, and privilege separation mechanisms to reduce the attack surface. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and maps to ATT&CK techniques involving privilege escalation and system binary exploitation. Regular security audits and kernel monitoring should be implemented to detect potential exploitation attempts and maintain system integrity against similar register manipulation attacks.