CVE-2008-2812 in Linux
Summary
by MITRE
The Linux kernel before 2.6.25.10 does not properly perform tty operations, which allows local users to cause a denial of service (system crash) or possibly gain privileges via vectors involving NULL pointer dereference of function pointers in (1) hamradio/6pack.c, (2) hamradio/mkiss.c, (3) irda/irtty-sir.c, (4) ppp_async.c, (5) ppp_synctty.c, (6) slip.c, (7) wan/x25_asy.c, and (8) wireless/strip.c in drivers/net/.
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Analysis
by VulDB Data Team • 08/01/2021
The vulnerability described in CVE-2008-2812 represents a critical flaw in the Linux kernel's handling of terminal tty operations across multiple network driver modules. This issue affects kernel versions prior to 2.6.25.10 and stems from improper validation of function pointers during tty operation processing. The flaw manifests as a NULL pointer dereference condition that can be exploited by local users to either crash the system or potentially escalate privileges. The vulnerability impacts eight distinct driver modules within the kernel's network subsystem, including hamradio drivers for packet radio communications, irda infrared drivers, ppp (point-to-point protocol) drivers, slip (serial line internet protocol) drivers, and wan (wide area network) drivers. These drivers are responsible for handling various communication protocols and serial connections, making the attack surface particularly broad and impactful.
The technical implementation of this vulnerability involves function pointer dereferences that occur when the kernel processes tty operations in the affected driver modules. When a malicious local user triggers specific tty operations through these drivers, the kernel fails to properly validate that function pointers are initialized before dereferencing them. This results in a NULL pointer dereference that causes the kernel to crash and reboot the system. According to CWE-476, this represents a NULL pointer dereference vulnerability where the program attempts to access memory through a pointer that has not been properly initialized. The attack vector is particularly concerning because it requires only local user privileges, making it accessible to users who have basic system access but not necessarily administrative rights. The exploitation can lead to either a denial of service condition that crashes the system or potentially allows privilege escalation if the kernel can be manipulated to execute arbitrary code with elevated privileges.
The operational impact of this vulnerability extends beyond simple system crashes, as it affects the stability and availability of systems running affected kernel versions. Network infrastructure servers, embedded systems, and devices that rely on these specific driver modules for communication protocols are particularly at risk. The vulnerability affects systems that utilize packet radio communications through hamradio drivers, infrared communication through irda drivers, point-to-point protocol connections, serial line internet protocol implementations, and various wide area network communication methods. Organizations using Linux-based systems for networking, telecommunications, or embedded applications may experience unexpected system outages or potential security breaches if these systems are not properly patched. The vulnerability's presence in wireless communication drivers also raises concerns for mobile and IoT devices that depend on these kernel components for network connectivity. The attack requires minimal privileges and can be executed through normal tty operations, making it particularly dangerous in environments where local access is not strictly controlled.
Mitigation strategies for this vulnerability require immediate kernel updates to version 2.6.25.10 or later, which contain the necessary patches to address the NULL pointer dereference conditions in the affected driver modules. System administrators should prioritize patching all systems running vulnerable kernel versions, particularly those in production environments where availability is critical. Additionally, implementing access controls to limit local user privileges where possible can reduce the attack surface, though this does not eliminate the vulnerability entirely. The patching process should include thorough testing to ensure that the updated kernel does not introduce compatibility issues with existing network drivers or applications. Security monitoring should be implemented to detect any attempts to exploit this vulnerability, and system logs should be reviewed for evidence of unauthorized access attempts. Organizations should also consider implementing network segmentation and privilege separation to limit the potential impact of successful exploitation. According to ATT&CK technique T1068, this vulnerability could be leveraged as part of a privilege escalation attack, making proper access controls and monitoring essential defensive measures. Regular vulnerability assessments and kernel updates should be part of ongoing security maintenance to prevent similar issues from affecting system availability and security posture.