CVE-2011-2480 in FreeBSD
Summary
by MITRE
Information Disclosure vulnerability in the 802.11 stack, as used in FreeBSD before 8.2 and NetBSD when using certain non-x86 architectures. A signedness error in the IEEE80211_IOC_CHANINFO ioctl allows a local unprivileged user to cause the kernel to copy large amounts of kernel memory back to the user, disclosing potentially sensitive information.
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Analysis
by VulDB Data Team • 11/28/2019
The CVE-2011-2480 vulnerability represents a critical information disclosure flaw within the 80211 wireless networking stack implementation across specific operating systems. This vulnerability specifically affects FreeBSD versions prior to 8.2 and NetBSD systems utilizing certain non-x86 architectures, highlighting the complex nature of wireless protocol implementations and their potential security implications. The flaw resides in the IEEE80211_IOC_CHANINFO ioctl handler, which is responsible for managing channel information within the wireless networking subsystem. This type of vulnerability demonstrates the inherent risks present when dealing with kernel-level operations that handle user-supplied data without proper validation.
The technical root cause of this vulnerability stems from a signedness error within the wireless driver's ioctl implementation. When processing the IEEE80211_IOC_CHANINFO command, the kernel fails to properly validate the size parameter provided by the user space application. This allows an unprivileged local user to manipulate the ioctl request to specify an excessively large buffer size, causing the kernel to copy an unintended amount of memory back to user space. The signedness error specifically occurs when the kernel treats a user-provided unsigned integer as if it were signed, leading to a scenario where negative values are interpreted as extremely large positive values. This fundamental flaw in parameter validation creates a direct pathway for information leakage from kernel memory regions.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with access to potentially sensitive kernel memory contents including cryptographic keys, network credentials, and system configuration data. Local unprivileged users can exploit this flaw to gain unauthorized access to kernel memory, potentially revealing confidential information that could be used for further exploitation or system compromise. The vulnerability is particularly concerning because it requires no special privileges or network access to exploit, making it accessible to any user with local system access. This characteristic places it in the category of local privilege escalation vulnerabilities, though it specifically targets information disclosure rather than direct privilege manipulation.
From a cybersecurity perspective, this vulnerability aligns with CWE-125: "Out-of-bounds Read" and represents a classic example of improper input validation within kernel space operations. The ATT&CK framework categorizes this as a technique for privilege escalation and information gathering, specifically under the T1003.002 sub-technique for "OS Credential Dumping" and T1082 for "System Information Discovery." The vulnerability demonstrates the importance of rigorous input validation and proper handling of user-supplied data within kernel contexts, where such flaws can have severe consequences for system security. Organizations using affected systems should prioritize patching and implementation of additional access controls to mitigate the risk of unauthorized information disclosure.
Mitigation strategies for this vulnerability primarily focus on applying the appropriate system updates and patches provided by the operating system vendors. FreeBSD users should upgrade to version 8.2 or later, while NetBSD users must ensure their systems are running on supported architectures or apply the relevant security patches. Additionally, system administrators should implement network segmentation and access controls to limit local user privileges, reducing the potential impact of exploitation. Monitoring for unusual ioctl activity patterns and implementing kernel memory protection mechanisms can also help detect and prevent exploitation attempts. The vulnerability underscores the necessity of maintaining current security patches and conducting regular security assessments of kernel-level components to identify and remediate similar flaws before they can be exploited by malicious actors.