CVE-2010-4074 in Linux
Summary
by MITRE
The USB subsystem in the Linux kernel before 2.6.36-rc5 does not properly initialize certain structure members, which allows local users to obtain potentially sensitive information from kernel stack memory via vectors related to TIOCGICOUNT ioctl calls, and the (1) mos7720_ioctl function in drivers/usb/serial/mos7720.c and (2) mos7840_ioctl function in drivers/usb/serial/mos7840.c.
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Analysis
by VulDB Data Team • 10/05/2021
The vulnerability described in CVE-2010-4074 represents a classic case of improper initialization in kernel space code that exposes sensitive information through information disclosure mechanisms. This flaw exists within the Linux kernel's USB subsystem and specifically affects versions prior to 2.6.36-rc5, making it a significant concern for systems running older kernel versions. The vulnerability manifests through two distinct kernel functions: mos7720_ioctl in drivers/usb/serial/mos7720.c and mos7840_ioctl in drivers/usb/serial/mos7840.c, both of which handle ioctl operations for USB serial devices. The root cause lies in the failure to properly initialize certain structure members before using them in the context of TIOCGICOUNT ioctl calls, which are typically used to retrieve serial port statistics and status information.
The technical exploitation of this vulnerability relies on the principle of information leakage through uninitialized memory contents that remain in kernel stack memory. When the mos7720_ioctl and mos7840_ioctl functions process TIOCGICOUNT requests, they fail to initialize specific data structures before populating them with information from kernel memory. This initialization failure means that sensitive data previously stored in the uninitialized memory locations may be inadvertently exposed to user-space applications. The vulnerability falls under CWE-457, which specifically addresses the use of uninitialized variables, and more broadly relates to CWE-248, concerning the exposure of uninitialized memory. Attackers can leverage this flaw by executing ioctl calls against USB serial devices, causing the kernel to return kernel stack memory contents that may contain sensitive information such as cryptographic keys, passwords, or other confidential data.
The operational impact of CVE-2010-4074 extends beyond simple information disclosure, as it represents a fundamental security weakness in kernel memory management that could potentially enable more sophisticated attacks. Local attackers with access to the system can exploit this vulnerability to gain insights into kernel memory layout and potentially extract sensitive information that could aid in further exploitation attempts. The vulnerability is particularly concerning in environments where USB serial devices are frequently used, such as embedded systems, industrial control systems, or server environments with extensive USB device connectivity. From an ATT&CK perspective, this vulnerability aligns with techniques involving privilege escalation and information gathering, as it allows local users to extract kernel memory contents that could reveal system state information or sensitive data structures. The attack surface is limited to local users with access to USB serial devices, but the potential for escalation exists if the leaked information can be used to craft more targeted attacks against the kernel or other system components.
Mitigation strategies for CVE-2010-4074 primarily involve upgrading to kernel versions 2.6.36-rc5 or later, where the initialization issues have been addressed through proper structure initialization in the affected USB serial driver functions. System administrators should prioritize kernel updates, particularly in production environments where USB serial devices are actively used. Additionally, implementing proper access controls to USB device interfaces can limit the attack surface, though this does not address the underlying kernel vulnerability. The fix implemented in the patched kernel versions ensures that all structure members are properly initialized before being populated with data, eliminating the possibility of information leakage through uninitialized memory contents. Organizations should also consider monitoring for suspicious ioctl activity against USB serial devices as part of their security operations, as this vulnerability could potentially be leveraged as part of a broader attack chain where information gathering precedes more targeted exploitation attempts.