CVE-2003-0461 in Linux
Summary
by MITRE
/proc/tty/driver/serial in Linux 2.4.x reveals the exact number of characters used in serial links, which could allow local users to obtain potentially sensitive information such as the length of passwords.
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Analysis
by VulDB Data Team • 06/01/2019
The vulnerability identified as CVE-2003-0461 represents a significant information disclosure issue within the Linux kernel's serial driver implementation. This flaw exists in the /proc/tty/driver/serial interface of Linux 2.4.x systems where the kernel exposes detailed statistics about serial communication channels. The specific technical weakness lies in how the kernel's serial driver reports character count information through the proc filesystem, making it possible for local attackers to extract precise data about serial link usage patterns. The vulnerability stems from insufficient access control and information hiding mechanisms within the kernel's tty subsystem, which is designed to manage terminal I/O operations and serial communication protocols.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potentially sensitive metadata about serial communication activities. When local users can determine the exact number of characters transmitted over serial links, they gain insights into password lengths, protocol message structures, and communication patterns that could aid in more sophisticated attacks. This information leakage occurs through the /proc/tty/driver/serial interface which exposes internal kernel data structures containing serial port statistics including character counts, buffer usage, and transmission metrics. The vulnerability is particularly concerning because it operates at the kernel level and requires no special privileges beyond local access, making it easily exploitable by any user with shell access to the system.
Security implications of CVE-2003-0461 align with CWE-200 (Information Exposure) and can be categorized under ATT&CK technique T1082 (System Information Discovery) as it enables adversaries to gather system metadata. The vulnerability demonstrates poor principle of least privilege implementation within the kernel's proc filesystem interface, where sensitive operational data about serial communications is exposed without proper access controls. This flaw contributes to the broader category of information leakage vulnerabilities that can facilitate credential guessing attacks, protocol analysis, and system reconnaissance activities. The specific nature of the information revealed through this vulnerability makes it particularly dangerous in environments where serial communication protocols are used for authentication, system management, or secure data transfer operations.
Mitigation strategies for this vulnerability primarily involve upgrading to newer kernel versions where the serial driver implementation has been improved and access controls have been strengthened. System administrators should implement proper kernel hardening measures including disabling unnecessary proc filesystem entries and restricting access to sensitive kernel interfaces. The recommended approach includes applying security patches from kernel vendors, implementing proper access controls on /proc filesystem entries, and conducting regular security audits of kernel interfaces. Additionally, organizations should consider implementing monitoring solutions that can detect unusual access patterns to kernel interfaces and establish proper network segmentation to limit local user privileges. The vulnerability serves as a reminder of the importance of proper information hiding mechanisms in kernel design and the need for comprehensive security reviews of system interfaces that expose internal operational data.