CVE-2011-2492 in Linux
Summary
by MITRE
The bluetooth subsystem in the Linux kernel before 3.0-rc4 does not properly initialize certain data structures, which allows local users to obtain potentially sensitive information from kernel memory via a crafted getsockopt system call, related to (1) the l2cap_sock_getsockopt_old function in net/bluetooth/l2cap_sock.c and (2) the rfcomm_sock_getsockopt_old function in net/bluetooth/rfcomm/sock.c.
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Analysis
by VulDB Data Team • 11/15/2021
The vulnerability identified as CVE-2011-2492 represents a critical information disclosure flaw within the Linux kernel's bluetooth subsystem affecting versions prior to 3.0-rc4. This issue stems from inadequate initialization of kernel data structures during bluetooth socket operations, creating a pathway for local attackers to extract sensitive information from kernel memory spaces. The vulnerability specifically impacts the l2cap_sock_getsockopt_old and rfcomm_sock_getsockopt_old functions, which handle socket option retrieval operations for bluetooth l2cap and rfcomm protocols respectively. The flaw manifests when these functions fail to properly initialize memory buffers before returning data to user-space applications, potentially exposing kernel memory contents including cryptographic keys, credentials, or other confidential information to unauthorized local users.
The technical implementation of this vulnerability involves the improper handling of socket option requests within the bluetooth subsystem's legacy socket functions. When a local user process invokes getsockopt with specific parameters against bluetooth sockets, the kernel's l2cap_sock_getsockopt_old and rfcomm_sock_getsockopt_old functions do not adequately clear or initialize the memory areas that will be returned to the user application. This incomplete initialization leaves residual data from previous kernel operations within the response buffer, effectively creating a memory leak that exposes kernel memory contents. The vulnerability is classified as a local privilege escalation vector since it requires local access but can potentially provide attackers with information that could be leveraged for further exploitation. This weakness directly relates to CWE-248, which addresses the exposure of uninitialized variables, and aligns with ATT&CK technique T1005 for data from local system.
The operational impact of CVE-2011-2492 extends beyond simple information disclosure, as the leaked kernel memory may contain sensitive cryptographic material, session tokens, or other confidential data that could be exploited by attackers with local access. While the vulnerability is limited to local users, it creates a significant risk for systems where local access is possible, such as shared environments, development systems, or servers with compromised local accounts. The exposure of kernel memory could potentially reveal information that would aid in bypassing security mechanisms or developing more sophisticated attacks against the system. This vulnerability affects the integrity and confidentiality of the kernel's memory space, undermining the fundamental security assumptions of the kernel's isolation properties and potentially enabling privilege escalation attacks when combined with other vulnerabilities. Organizations running affected kernel versions should prioritize patching to prevent potential exploitation and maintain system integrity.
Mitigation strategies for CVE-2011-2492 center on upgrading to kernel versions 3.0-rc4 or later, where the improper data structure initialization has been corrected. System administrators should also implement proper access controls to limit local user privileges and monitor for unauthorized local access attempts. The vulnerability demonstrates the importance of proper memory initialization in kernel space operations and highlights the need for comprehensive security testing of system call handlers. Additional protective measures include monitoring bluetooth subsystem usage patterns and implementing network segmentation to limit potential attack vectors, though the primary defense remains the kernel upgrade to address the root cause of the uninitialized memory exposure.