CVE-2002-0973 in FreeBSD
Summary
by MITRE
Integer signedness error in several system calls for FreeBSD 4.6.1 RELEASE-p10 and earlier may allow attackers to access sensitive kernel memory via large negative values to the (1) accept, (2) getsockname, and (3) getpeername system calls, and the (4) vesa FBIO_GETPALETTE ioctl.
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Analysis
by VulDB Data Team • 09/06/2019
This vulnerability represents a critical integer signedness error affecting FreeBSD versions 4.6.1 RELEASE-p10 and earlier systems. The flaw manifests in multiple system calls and ioctl operations where the kernel fails to properly validate input parameters, specifically when negative values are passed to the accept, getsockname, getpeername system calls, and the vesa FBIO_GETPALETTE ioctl. The underlying issue stems from improper handling of signed integer values in kernel space operations, creating a pathway for attackers to manipulate memory access patterns through carefully crafted negative parameters.
The technical implementation of this vulnerability exploits the fundamental difference between signed and unsigned integer representations in kernel memory management. When these system calls receive large negative values, the kernel's internal processing routines fail to properly constrain the parameter ranges, allowing attackers to bypass normal boundary checks. This creates opportunities for memory address manipulation and unauthorized access to kernel memory regions that should remain protected from user-space processes. The vulnerability is particularly dangerous because it operates at the kernel level where privilege escalation is not required to exploit the flaw, as the kernel itself becomes the vector for memory access.
The operational impact of CVE-2002-0973 extends beyond simple information disclosure, as it enables attackers to potentially read arbitrary kernel memory locations and extract sensitive data such as cryptographic keys, passwords, or other confidential information stored in kernel memory. The attack surface includes network socket operations and video framebuffer operations, making this vulnerability particularly dangerous in multi-user environments where network services are running. According to CWE classification, this vulnerability maps to CWE-191, Integer Underflow (Wrap or Wraparound), though the specific manifestation involves signedness handling errors rather than traditional underflow conditions. The vulnerability also aligns with ATT&CK technique T1068, Exploitation for Privilege Escalation, as it allows for kernel-level memory access without requiring elevated privileges.
Mitigation strategies for this vulnerability require immediate system updates to FreeBSD versions that address the integer signedness errors in the affected system calls. System administrators should prioritize patching affected systems and implementing network segmentation to limit exposure of vulnerable services. Additional protective measures include monitoring network traffic for suspicious parameter patterns in socket operations and implementing kernel hardening techniques such as stack canaries and address space layout randomization. The vulnerability demonstrates the critical importance of proper input validation in kernel space operations and highlights the need for comprehensive security testing of system call interfaces to prevent similar issues in future implementations. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts targeting these specific kernel interfaces.