CVE-2003-0619 in Linux
Summary
by MITRE
Integer signedness error in the decode_fh function of nfs3xdr.c in Linux kernel before 2.4.21 allows remote attackers to cause a denial of service (kernel panic) via a negative size value within XDR data of an NFSv3 procedure call.
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Analysis
by VulDB Data Team • 10/07/2024
The vulnerability identified as CVE-2003-0619 represents a critical integer signedness error within the Linux kernel's Network File System version 3 implementation. This flaw exists in the decode_fh function located in the nfs3xdr.c file, which processes XDR (External Data Representation) data structures used for network communication in NFSv3 protocol operations. The issue manifests when the kernel receives malformed XDR data containing negative size values during NFSv3 procedure calls, creating a condition where unsigned integer variables are improperly handled as signed values. This particular vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, specifically demonstrating how improper handling of signedness can lead to system instability. The flaw affects Linux kernel versions prior to 2.4.21, making it a significant concern for systems running older kernel versions that were prevalent during the early 2000s era.
The technical exploitation of this vulnerability occurs when an NFS client sends malformed XDR data to an NFS server running an affected kernel version. During the processing of these data structures, the decode_fh function attempts to interpret size values without proper validation of their signedness properties. When a negative value is encountered where an unsigned integer is expected, the kernel's arithmetic operations can produce unexpected results that ultimately trigger a kernel panic. This panic occurs because the kernel's memory management and data validation mechanisms fail to handle the unexpected negative size value properly, leading to a complete system crash. The vulnerability demonstrates how XDR decoding routines can become entry points for denial of service attacks, particularly when dealing with protocol implementations that do not adequately validate data boundaries and type expectations. This issue directly maps to ATT&CK technique T1499.004 for Denial of Service through resource exhaustion, as the attack effectively consumes kernel resources and causes system instability.
The operational impact of CVE-2003-0619 extends beyond simple service disruption to encompass complete system availability compromise. Organizations running affected kernel versions would experience unexpected system crashes and reboots whenever malicious or malformed NFSv3 requests are processed, creating significant downtime and potential data loss scenarios. The vulnerability's remote nature means that attackers could exploit this weakness from network locations without requiring local access, making it particularly dangerous in networked environments where NFS services are exposed to untrusted networks. System administrators would face challenges in detecting and mitigating such attacks, as the kernel panic would appear as an unexpected system failure rather than a clear indication of malicious activity. This vulnerability particularly affected enterprise environments where NFS services were commonly used for file sharing and storage access, potentially disrupting critical business operations. The lack of proper input validation in the XDR decoding process represents a fundamental flaw in the kernel's security architecture, as it fails to implement proper bounds checking and data sanitization for network-received information. The vulnerability underscores the importance of proper integer type handling in kernel space operations and demonstrates how seemingly minor implementation details can result in catastrophic system failures. Organizations implementing mitigation strategies would need to upgrade to kernel versions 2.4.21 or later, which contain the necessary patches to address the signedness error in the decode_fh function, thereby preventing the exploitation of this denial of service vulnerability.