CVE-2005-4782 in NetBSD
Summary
by MITRE
NetBSD 2.0 before 2.0.4, 2.1 before 2.1.1, and 3, when the kernel is compiled with "options DIAGNOSTIC," allows local users to cause a denial of service (kernel assertion panic) via a negative linger time in the SO_LINGER socket option.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/16/2018
The vulnerability described in CVE-2005-4782 represents a critical kernel-level flaw in NetBSD operating systems affecting versions prior to specific patch releases. This issue manifests when the kernel is compiled with the DIAGNOSTIC options flag, which enables additional debugging and validation checks within the kernel code. The vulnerability specifically targets the socket layer implementation where the SO_LINGER socket option is handled, creating a condition that can be exploited by local users to trigger kernel assertion failures and subsequent system panics.
The technical root cause of this vulnerability lies in the insufficient input validation within the kernel's socket implementation. When a negative linger time value is provided through the SO_LINGER socket option, the kernel fails to properly validate this input before processing it. This lack of proper validation allows malicious local users to craft socket operations that deliberately pass negative values to the linger time parameter, which then triggers kernel assertion checks that were designed to catch programming errors during development. The DIAGNOSTIC compilation flag makes these assertions active in production kernels, turning what should be a benign input validation issue into a potential denial of service vector.
From an operational perspective, this vulnerability presents a significant risk to systems running affected NetBSD versions, particularly in environments where local user access cannot be strictly controlled. The impact of exploitation results in immediate system instability through kernel assertion panics, effectively causing a denial of service condition that requires manual system reboot to resolve. The vulnerability is particularly concerning because it requires no special privileges beyond local access and can be triggered through standard socket programming interfaces, making it accessible to any user with basic system access. This makes it especially dangerous in multi-user environments or systems where untrusted local users may exist.
The vulnerability aligns with CWE-129, which describes improper validation of array indices, and CWE-248, which covers exposure of an uninitialized variable. The attack pattern corresponds to the ATT&CK technique T1499.004, specifically focusing on network denial of service through kernel exploitation. The flaw demonstrates poor input validation practices in kernel space code, where user-supplied parameters are not adequately sanitized before being processed by kernel functions. Organizations should immediately implement the available patches for NetBSD versions 2.0.4, 2.1.1, and 3.0 to address this vulnerability, as the kernel panic conditions can lead to complete system unavailability and potential data loss during recovery operations. The patch implementation should include comprehensive testing to ensure that the fix does not introduce regressions in legitimate socket operations while properly handling the negative linger time validation.