CVE-2010-2693 in FreeBSD
Summary
by MITRE
FreeBSD 7.1 through 8.1-PRERELEASE does not copy the read-only flag when creating a duplicate mbuf buffer reference, which allows local users to cause a denial of service (system file corruption) and gain privileges via the sendfile system call.
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Analysis
by VulDB Data Team • 08/30/2024
The vulnerability identified as CVE-2010-2693 affects FreeBSD operating systems versions 7.1 through 8.1-PRERELEASE and represents a critical flaw in the kernel's memory buffer management system. This issue stems from improper handling of mbuf (memory buffer) structures during the duplicate buffer reference creation process, specifically failing to maintain the read-only flag attribute when duplicating buffer references. The mbuf system serves as FreeBSD's fundamental data structure for network packet handling and memory management, making this vulnerability particularly dangerous as it operates at the kernel level where privilege escalation and system stability are paramount.
The technical implementation of this vulnerability occurs within the sendfile system call which is designed to efficiently transfer data between file descriptors, typically used for serving files over network connections. When a local user crafts a specific sequence of operations involving sendfile calls, the kernel's mbuf duplication mechanism fails to properly propagate the read-only flag from the original buffer to the duplicated reference. This oversight creates a scenario where the duplicated buffer can be modified in ways that were originally prevented by the read-only flag, leading to potential memory corruption and system instability.
The operational impact of this vulnerability manifests in two primary ways that align with common attack patterns documented in the MITRE ATT&CK framework. First, local users can exploit this flaw to cause denial of service conditions through system file corruption, disrupting normal system operations and potentially rendering services unavailable. Second, and more critically, the vulnerability enables privilege escalation attacks by allowing attackers to manipulate memory structures in ways that bypass normal access controls. This dual nature makes the vulnerability particularly attractive to attackers seeking both system disruption and unauthorized access to elevated privileges.
From a cybersecurity perspective, this vulnerability demonstrates the importance of maintaining data integrity and access control mechanisms even within kernel-level operations. The flaw relates to CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow conditions, as the improper buffer handling creates opportunities for memory corruption. The vulnerability also maps to ATT&CK technique T1068, which involves the exploitation of remote services to gain system privileges, and T1499, which covers the disruption of services through system file corruption. Organizations should implement immediate mitigations including system updates to patched FreeBSD versions, network segmentation to limit local user access, and monitoring for unusual sendfile system call patterns that might indicate exploitation attempts.