CVE-2012-6537 in Linux
Summary
by MITRE
net/xfrm/xfrm_user.c in the Linux kernel before 3.6 does not initialize certain structures, which allows local users to obtain sensitive information from kernel memory by leveraging the CAP_NET_ADMIN capability.
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Analysis
by VulDB Data Team • 01/01/2022
The vulnerability identified as CVE-2012-6537 resides within the Linux kernel's implementation of the IPsec framework, specifically in the xfrm_user.c component that handles user-space communication with the kernel's IPsec subsystem. This flaw represents a classic information disclosure vulnerability that arises from improper initialization of kernel data structures, allowing unauthorized access to sensitive memory contents that should remain protected. The vulnerability affects Linux kernel versions prior to 3.6 and requires an attacker to possess the CAP_NET_ADMIN capability, which is typically available to network administrators or processes with elevated privileges.
The technical root cause of this vulnerability stems from the failure to properly initialize certain kernel structures within the xfrm_user.c file when processing user-space requests. When the kernel processes IPsec configuration operations through the xfrm_user interface, it fails to initialize all fields of specific data structures before returning information to user-space applications. This incomplete initialization leaves portions of kernel memory uninitialized, potentially containing sensitive data from previous operations or kernel internals. The vulnerability manifests when an attacker with CAP_NET_ADMIN capability makes specific xfrm_user API calls that trigger the kernel to return these uninitialized structures to user-space, thereby exposing kernel memory contents that could include passwords, cryptographic keys, or other confidential information.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potential access to kernel memory that may contain sensitive data such as cryptographic keys, session information, or other confidential system data. This information exposure could be leveraged by attackers to escalate privileges, conduct further attacks, or gain deeper insights into the system's internal state. The requirement for CAP_NET_ADMIN capability means that this vulnerability typically affects systems where network administrators have elevated privileges, but it could also be exploited by attackers who have already gained access to a privileged network account. The vulnerability is particularly concerning in environments where IPsec is actively used for network security, as it could potentially expose encryption keys or other cryptographic material that would otherwise remain protected.
The vulnerability aligns with CWE-119, which addresses improper access to kernel memory, and represents a variant of information disclosure flaws that can have significant security implications. From an ATT&CK perspective, this vulnerability maps to techniques involving privilege escalation and credential access, as the exposure of kernel memory could provide attackers with information necessary to compromise system security. The exploitability of this vulnerability is limited by the requirement for CAP_NET_ADMIN capability, but it remains a serious concern for systems where this capability is accessible to untrusted users or processes. Organizations should prioritize applying kernel updates to address this vulnerability, particularly in environments where IPsec is deployed and where the risk of privilege escalation through information disclosure is a concern.
Mitigation strategies for CVE-2012-6537 primarily involve upgrading to Linux kernel version 3.6 or later, where the kernel properly initializes the affected structures. System administrators should also implement strict access controls to prevent unauthorized users from obtaining CAP_NET_ADMIN privileges, as this capability is essential for exploiting the vulnerability. Additional defensive measures include monitoring for unusual xfrm_user API activity and implementing network segmentation to limit the potential impact of exploitation. Organizations should also conduct regular security assessments to identify systems running vulnerable kernel versions and ensure that all systems maintain current security patches to protect against similar information disclosure vulnerabilities that may exist in other kernel components.