CVE-2017-1000200 in tcmu-runner
Summary
by MITRE
tcmu-runner version 1.0.5 to 1.2.0 is vulnerable to a dbus triggered NULL pointer dereference in the tcmu-runner daemon's on_unregister_handler() function resulting in denial of service
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Analysis
by VulDB Data Team • 01/10/2023
The vulnerability identified as CVE-2017-1000200 affects tcmu-runner daemon versions 1.0.5 through 1.2.0, presenting a critical security flaw that can be exploited through dbus communication channels. This daemon serves as a crucial component in Linux storage environments, facilitating communication between the kernel and userspace for target core unification operations. The vulnerability manifests as a NULL pointer dereference within the on_unregister_handler() function, which is triggered when the daemon processes specific dbus messages. The flaw represents a classic denial of service vulnerability that can be remotely exploited by adversaries who have access to the dbus interface, potentially disrupting storage services and causing system instability.
The technical root cause of this vulnerability lies in improper input validation and memory management within the tcmu-runner daemon's dbus handler implementation. When the daemon receives a specific unregister message through dbus, the on_unregister_handler() function fails to properly validate pointer references before attempting to dereference them. This NULL pointer dereference occurs because the function assumes certain data structures will be properly initialized, but malicious or malformed dbus messages can cause these structures to remain uninitialized. The vulnerability aligns with CWE-476 which specifically addresses NULL pointer dereference conditions, and demonstrates how improper error handling in daemon processes can lead to system-wide service disruption.
The operational impact of this vulnerability extends beyond simple denial of service, as it can compromise the stability of storage subsystems that rely on tcmu-runner for target operations. When exploited successfully, the vulnerability causes the tcmu-runner daemon to crash and terminate, which can result in loss of storage connectivity for applications and services that depend on the affected storage targets. This disruption can cascade through enterprise environments where storage availability is critical for database operations, virtualization platforms, and cloud infrastructure. The vulnerability is particularly concerning in production environments where storage reliability is paramount, as it can be triggered without authentication requirements, making it a significant threat to system availability.
Mitigation strategies for CVE-2017-1000200 should prioritize immediate patching of affected tcmu-runner versions to the latest stable releases that contain the necessary memory validation fixes. Organizations should also implement network segmentation to restrict dbus access to trusted administrative interfaces only, thereby reducing the attack surface for this vulnerability. Additionally, monitoring systems should be configured to detect abnormal daemon behavior and service interruptions that may indicate exploitation attempts. From a defensive perspective, this vulnerability highlights the importance of implementing proper input validation and error handling in daemon processes, aligning with ATT&CK technique T1499 which covers network denial of service attacks. System administrators should also consider implementing automated patch management processes to ensure timely remediation of similar vulnerabilities in storage subsystems, particularly given that this flaw represents a common pattern of memory management errors in daemon implementations.