CVE-2004-0814 in Linux
Summary
by MITRE
Multiple race conditions in the terminal layer in Linux 2.4.x, and 2.6.x before 2.6.9, allow (1) local users to obtain portions of kernel data via a TIOCSETD ioctl call to a terminal interface that is being accessed by another thread, or (2) remote attackers to cause a denial of service (panic) by switching from console to PPP line discipline, then quickly sending data that is received during the switch.
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Analysis
by VulDB Data Team • 06/29/2019
The vulnerability identified as CVE-2004-0814 represents a critical class of race conditions affecting the Linux terminal layer implementation across kernel versions 2.4.x and 2.6.x prior to 2.6.9. These race conditions occur within the terminal subsystem where concurrent access to terminal interfaces creates exploitable timing windows that can be leveraged by malicious actors. The flaw specifically targets the terminal layer's handling of ioctl operations and line discipline switching mechanisms, creating opportunities for both local privilege escalation and remote denial of service attacks. The vulnerability is categorized under CWE-362, which describes race conditions that can lead to security flaws when multiple threads or processes access shared resources without proper synchronization mechanisms.
The technical exploitation of this vulnerability occurs through two distinct attack vectors that leverage different aspects of the terminal subsystem's concurrency model. The first vector allows local users to perform kernel data leakage by utilizing the TIOCSETD ioctl call against terminal interfaces that are concurrently accessed by other threads. This creates a scenario where memory contents from kernel space can be inadvertently exposed to user-space processes through improper synchronization of terminal state modifications. The second vector involves remote attackers causing system panics by manipulating the console to PPP line discipline transition process, followed by rapid data transmission during the switch period. This attack exploits the timing window between when the line discipline switch begins and when the system properly transitions to the new discipline, allowing malicious data to trigger kernel panic conditions.
The operational impact of CVE-2004-0814 extends beyond simple denial of service scenarios to include potential privilege escalation and information disclosure capabilities. Local attackers can leverage the race condition to read kernel memory contents that should remain protected, potentially exposing sensitive system information, credentials, or cryptographic keys stored in kernel memory. The remote attack vector creates a reliable method for system administrators to experience unexpected kernel panics, leading to service disruption and potential data loss. These vulnerabilities particularly affect systems running older Linux kernel versions where proper synchronization mechanisms had not yet been implemented in the terminal subsystem, making them susceptible to concurrent access issues that could be exploited in both controlled and uncontrolled environments.
System administrators and security professionals should prioritize patching affected systems to address CVE-2004-0814, as the vulnerability exists in kernel versions that were widely deployed in enterprise and server environments during that time period. The recommended mitigation strategy involves upgrading to Linux kernel 2.6.9 or later, which includes proper synchronization mechanisms that prevent the race conditions exploited by this vulnerability. Additionally, implementing proper access controls and monitoring for unusual terminal activity can help detect potential exploitation attempts. Organizations should also consider applying the principle of least privilege to terminal access controls, limiting the ability of local users to perform ioctl operations that could trigger the vulnerable code paths. This vulnerability demonstrates the critical importance of proper synchronization in kernel-level code and aligns with ATT&CK technique T1068, which covers local privilege escalation through kernel vulnerabilities, as well as T1499, covering network denial of service attacks through system instability. The vulnerability serves as a historical example of how insufficient concurrency control in operating system kernels can create persistent security risks that require immediate remediation.