CVE-2003-0418 in Linux
Summary
by MITRE
The Linux 2.0 kernel IP stack does not properly calculate the size of an ICMP citation, which causes it to include portions of unauthorized memory in ICMP error responses.
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Analysis
by VulDB Data Team • 10/29/2024
The vulnerability identified as CVE-2003-0418 represents a critical flaw in the Linux 2.0 kernel's implementation of the Internet Control Message Protocol stack. This issue stems from improper handling of ICMP error message construction where the kernel fails to accurately calculate the size of ICMP citation data. The flaw affects systems running kernel versions prior to 2.4.22 and 2.6.0, making it particularly relevant to legacy systems and embedded devices that may not have received timely updates. The vulnerability is classified under CWE-125 as an "Out-of-bounds Read" which occurs when the kernel attempts to access memory regions beyond the intended buffer boundaries during ICMP error response generation.
The technical implementation of this vulnerability exploits the kernel's ICMP processing logic where it constructs error messages in response to malformed network packets. When an invalid packet is received, the kernel generates an ICMP error response containing a copy of the original packet data for diagnostic purposes. However, due to incorrect size calculation, the kernel includes additional memory content from adjacent memory locations in the ICMP citation portion of the error message. This memory leakage can potentially expose sensitive information including kernel memory addresses, user data, or system configuration details that should remain confidential. The flaw operates at the network protocol level within the kernel's network stack implementation, specifically affecting the ICMP error message construction routines that handle packet validation and response generation.
The operational impact of CVE-2003-0418 extends beyond simple information disclosure as it can enable attackers to gather intelligence about system memory layout and potentially facilitate more sophisticated attacks. The leaked memory contents may contain pointers to kernel data structures, stack contents, or other sensitive information that could be leveraged to identify system vulnerabilities or predict memory locations for exploitation. This vulnerability is particularly concerning in environments where multiple systems share the same kernel version, as it could allow an attacker to gather system fingerprinting information that aids in targeting specific system configurations. The vulnerability aligns with ATT&CK technique T1082 for system information discovery and T1592 for vulnerability scanning, as it provides an automated method for gathering system memory characteristics.
Mitigation strategies for CVE-2003-0418 primarily involve upgrading to kernel versions 2.4.22 or 2.6.0 and later, which contain the necessary patches to properly calculate ICMP citation sizes and prevent memory leakage. System administrators should prioritize updating kernel versions across all production systems, particularly those running legacy Linux 2.0 kernel variants. Additional defensive measures include implementing network segmentation to limit exposure, deploying intrusion detection systems that can monitor for anomalous ICMP traffic patterns, and conducting regular vulnerability assessments to identify systems running vulnerable kernel versions. The patch for this vulnerability specifically addresses the buffer size calculation in the ICMP error message generation code, ensuring that only the appropriate amount of original packet data is included in error responses without leaking unauthorized memory contents. Organizations should also consider implementing network access controls and firewall rules to limit ICMP traffic where possible, reducing the attack surface for this and similar network-based vulnerabilities.