CVE-2010-4242 in Linux
Summary
by MITRE
The hci_uart_tty_open function in the HCI UART driver (drivers/bluetooth/hci_ldisc.c) in the Linux kernel 2.6.36, and possibly other versions, does not verify whether the tty has a write operation, which allows local users to cause a denial of service (NULL pointer dereference) via vectors related to the Bluetooth driver.
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Analysis
by VulDB Data Team • 07/01/2024
The vulnerability described in CVE-2010-4242 resides within the Linux kernel's Bluetooth subsystem, specifically in the HCI UART driver component that manages serial communication for Bluetooth devices. This flaw exists in kernel versions up to and including 2.6.36, making it a significant concern for systems running these older kernel versions. The issue stems from insufficient input validation within the hci_uart_tty_open function which handles the opening of tty devices for Bluetooth communication. When a local user attempts to establish a Bluetooth connection through the serial interface, the driver fails to properly validate whether the underlying tty structure supports write operations before proceeding with the connection process.
The technical implementation of this vulnerability manifests as a NULL pointer dereference condition that occurs when the driver attempts to access a write function pointer that has not been properly initialized. This occurs because the hci_uart_tty_open function does not perform adequate checks to verify that the tty device being opened has a valid write operation handler. When a malicious local user exploits this weakness by initiating specific Bluetooth communication sequences, the kernel's Bluetooth driver attempts to invoke a write operation on a NULL pointer, resulting in an immediate system crash and subsequent denial of service condition. The vulnerability represents a classic case of improper input validation and resource management within kernel space code.
From an operational perspective, this vulnerability presents a serious security risk as it allows any local user to trigger a system crash without requiring elevated privileges. The impact extends beyond simple service disruption since a successful exploitation can render the entire system unstable, potentially requiring manual reboot to restore normal operation. This makes the vulnerability particularly dangerous in production environments where system availability is critical, as it can be exploited by malicious users with minimal privileges to cause significant operational disruption. The vulnerability affects systems running affected kernel versions regardless of whether Bluetooth hardware is present, as the flaw exists in the kernel's Bluetooth driver framework itself.
The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and it can be categorized under the ATT&CK technique T1499.004 for network denial of service. The exploitation pathway demonstrates how local privilege escalation opportunities can be leveraged to achieve system-level impact through kernel-level flaws. Mitigation strategies include upgrading to kernel versions where this vulnerability has been patched, typically kernel 2.6.37 and later releases. System administrators should also implement proper kernel update policies and monitor for vulnerable systems. Additional protective measures include restricting local user access to Bluetooth functionality when possible and implementing proper kernel hardening techniques to minimize the attack surface. Organizations should conduct thorough vulnerability assessments to identify systems running affected kernel versions and prioritize patch deployment to prevent exploitation attempts.