CVE-2005-0708 in FreeBSD
Summary
by MITRE
The sendfile system call in FreeBSD 4.8 through 4.11 and 5 through 5.4 can transfer portions of kernel memory if a file is truncated while it is being sent, which could allow remote attackers to obtain sensitive information.
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Analysis
by VulDB Data Team • 07/02/2019
The vulnerability described in CVE-2005-0708 represents a critical information disclosure flaw in the FreeBSD operating system's implementation of the sendfile system call. This issue affects FreeBSD versions 4.8 through 4.11 and 5 through 5.4, where the kernel memory management during file transmission operations becomes compromised when files are truncated during the sendfile process. The fundamental problem lies in how the kernel handles memory mapping and file descriptor management when a file's size is altered while it is being transmitted through the network stack. This flaw creates a potential avenue for attackers to extract sensitive kernel memory contents, which could include cryptographic keys, passwords, or other confidential system information.
The technical implementation of this vulnerability stems from improper handling of memory regions when the sendfile system call encounters a file that has been modified or truncated during the transmission process. When a file is truncated while being sent, the kernel's memory management routines fail to properly validate or sanitize the memory pointers, leading to the possibility that portions of kernel memory may be inadvertently exposed to userspace processes. This issue directly maps to CWE-200, which defines weaknesses related to information exposure, and represents a classic case of improper information handling during system call execution. The vulnerability exploits the fundamental interaction between the virtual memory subsystem and network I/O operations, where the kernel's memory mapping structures become inconsistent with the actual file state.
The operational impact of CVE-2005-0708 is significant, as it provides remote attackers with the capability to obtain sensitive information from the kernel memory space without requiring local access or elevated privileges. Attackers can potentially exploit this vulnerability by initiating a sendfile operation on a file while simultaneously truncating that file, thereby causing the kernel to transfer memory contents that should remain protected. This type of information disclosure can lead to system compromise, as the leaked kernel memory may contain credentials, encryption keys, or other critical system data that could be leveraged for further attacks. The vulnerability demonstrates how seemingly benign file operations can create security implications when combined with improper memory management in kernel space, aligning with ATT&CK technique T1005 for data from local system.
Mitigation strategies for this vulnerability involve immediate patching of affected FreeBSD systems to versions that address the memory management inconsistency in the sendfile implementation. System administrators should ensure that all FreeBSD systems within their environment are updated to patched versions that properly handle file truncation during sendfile operations. Additionally, network monitoring should be implemented to detect unusual patterns in file access and network I/O operations that might indicate exploitation attempts. The vulnerability highlights the importance of proper kernel memory validation and the need for thorough testing of system call implementations under concurrent file modification conditions. Organizations should also consider implementing access controls and monitoring for sensitive file operations, particularly those involving network I/O and memory management functions, to reduce the attack surface and detect potential exploitation attempts.