CVE-2003-1040 in Linux
Summary
by MITRE
kmod in the Linux kernel does not set its uid, suid, gid, or sgid to 0, which allows local users to cause a denial of service (crash) by sending certain signals to kmod.
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Analysis
by VulDB Data Team • 09/05/2019
The vulnerability identified as CVE-2003-1040 resides within the kmod subsystem of the Linux kernel, representing a critical security flaw that affects the proper initialization of kernel module loading mechanisms. This issue specifically targets the kmod utility which serves as the kernel module loading interface, responsible for dynamically loading and unloading kernel modules from user space. The vulnerability stems from improper privilege management during the kmod execution context setup, where the utility fails to correctly establish its security context with root privileges. According to CWE-276, this represents a classic inadequate privilege management issue where the system does not properly enforce access controls, creating an opportunity for malicious local users to exploit the system's trust model.
The technical flaw manifests when kmod fails to set its uid, suid, gid, or sgid to zero during execution, leaving the process running with elevated privileges but without proper security context initialization. This creates a scenario where local users can manipulate the kmod process through signal handling mechanisms to trigger kernel-level crashes or system instability. The vulnerability operates through the signal delivery mechanism, where specific signals sent to the kmod process can cause it to enter an undefined state, ultimately leading to kernel panic or system crash. The flaw essentially allows for a form of privilege escalation through process manipulation, as the system's module loading infrastructure becomes vulnerable to signal-based attacks that can disrupt normal system operations.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a potential pathway for more sophisticated attacks that could compromise system integrity. Local users with minimal privileges can exploit this flaw to crash the kernel, potentially causing data loss, service disruption, and system instability that affects the entire computing environment. The vulnerability is particularly concerning because it operates at the kernel level, meaning that even if the user has limited privileges, they can leverage this flaw to cause system-wide disruptions. This aligns with ATT&CK technique T1068 which describes the use of local privilege escalation techniques to gain higher-level access within a system, though in this case the exploitation is more focused on system stability rather than access control bypass.
Mitigation strategies for CVE-2003-1040 primarily involve updating the Linux kernel to versions that properly initialize the kmod utility's security context, ensuring that uid, suid, gid, and sgid are correctly set to zero upon execution. System administrators should also implement proper access controls and monitoring of kernel module loading activities, as well as apply the latest security patches from their distribution vendors. The vulnerability highlights the importance of proper privilege management in kernel space components and demonstrates how seemingly minor initialization flaws can create significant security risks. Additionally, organizations should consider implementing process monitoring and alerting systems to detect unusual signal handling patterns that might indicate exploitation attempts, as this vulnerability can be leveraged as part of broader attack strategies targeting system stability and availability.