CVE-2009-2483 in NetBSD
Summary
by MITRE
libprop/prop_object.c in proplib in NetBSD 4.0 and 4.0.1 allows local users to cause a denial of service (NULL pointer dereference and kernel panic) via a malformed externalized plist (XML form) containing an undefined element.
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Analysis
by VulDB Data Team • 11/18/2018
The vulnerability identified as CVE-2009-2483 resides within the proplib library component of NetBSD operating systems version 4.0 and 4.0.1. This issue manifests as a denial of service condition that can be triggered through manipulation of externalized property list files in XML format. The proplib library serves as a fundamental component for handling property lists within the NetBSD kernel, providing essential functionality for system configuration and inter-process communication. When processing malformed XML property lists containing undefined elements, the library fails to properly validate input data, leading to critical system instability.
The technical flaw stems from inadequate input validation within the prop_object.c file, specifically in how the library handles undefined elements during the parsing of externalized plist data. When a local user crafts a malicious XML file containing malformed property list structures with undefined elements, the proplib library attempts to dereference a NULL pointer during the processing phase. This NULL pointer dereference represents a classic kernel-level programming error that directly results in system crashes and kernel panics. The vulnerability operates at the kernel level, making it particularly dangerous as it can be exploited by any local user with minimal privileges, requiring no special administrative access or network connectivity.
The operational impact of this vulnerability extends beyond simple service disruption, as it can lead to complete system unavailability through kernel panics that require manual rebooting of affected systems. Local users can exploit this weakness to repeatedly crash the system, creating persistent denial of service conditions that can severely impact system reliability and availability. This vulnerability particularly affects systems running NetBSD 4.0 and 4.0.1 where the proplib library is actively used for property list processing. The attack vector is straightforward and accessible, requiring only local file system access to create and execute the malicious XML files, making it a significant concern for system administrators who may not be aware of the potential for local privilege escalation through system instability.
Security mitigations for this vulnerability involve immediate system updates and patches provided by NetBSD developers to address the NULL pointer dereference issue in the proplib library. System administrators should prioritize applying the relevant security patches that correct the input validation procedures in prop_object.c. Additionally, implementing proper input sanitization measures and validating all externalized property list data before processing can help prevent similar vulnerabilities from manifesting in other applications. Organizations should also consider monitoring for unauthorized local access attempts and implementing robust system logging to detect potential exploitation attempts. This vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a typical example of how improper input validation can lead to system instability. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques through system instability and denial of service conditions that can be leveraged to disrupt normal system operations and potentially create opportunities for further exploitation.