CVE-2006-6107 in D-Bus
Summary
by MITRE
Unspecified vulnerability in the match_rule_equal function in bus/signals.c in D-Bus before 1.0.2 allows local applications to remove match rules for other applications and cause a denial of service (lost process messages).
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Analysis
by VulDB Data Team • 07/12/2019
The vulnerability described in CVE-2006-6107 resides within the D-Bus message bus system, specifically in the match_rule_equal function located in bus/signals.c. This issue affects D-Bus versions prior to 1.0.2 and represents a significant security flaw that undermines the integrity of the message passing infrastructure. The vulnerability manifests as a local privilege escalation opportunity where malicious applications can manipulate the message routing mechanisms to disrupt communication between legitimate processes. The D-Bus system serves as a fundamental communication layer in many Linux desktop environments and server configurations, making this vulnerability particularly concerning for system stability and security.
The technical flaw stems from improper validation within the match_rule_equal function which handles rule matching for D-Bus signal subscriptions. When local applications attempt to manipulate match rules, the function fails to properly verify the legitimacy of rule modifications, allowing unauthorized processes to interfere with the subscription mechanisms of other applications. This weakness creates a condition where an attacker can effectively remove or modify match rules that govern how messages are delivered to various processes, leading to the disruption of expected communication patterns. The vulnerability operates at the kernel level within the D-Bus daemon, making it particularly dangerous as it can affect the entire message bus infrastructure rather than individual applications. This type of flaw aligns with CWE-284 Access Control issues, specifically involving improper access control mechanisms within system-level components.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially compromise the stability of entire desktop environments or server applications that depend on D-Bus for inter-process communication. When match rules are improperly removed or modified, legitimate applications may lose critical messages, leading to application crashes, data loss, or complete service unavailability. The local nature of this vulnerability means that any application running with user privileges can potentially exploit it, making it particularly dangerous in multi-user environments where untrusted applications may be present. This vulnerability directly impacts the availability and integrity of D-Bus services, which are critical for desktop environments like GNOME and KDE, as well as numerous server applications that rely on standardized messaging protocols for system coordination and service discovery.
Mitigation strategies for this vulnerability primarily focus on immediate patching and system updates to D-Bus versions 1.0.2 and later, which contain the necessary fixes for the match_rule_equal function. System administrators should prioritize updating their D-Bus implementations and verify that all applications are running on patched versions to prevent exploitation. Additionally, implementing proper access controls and monitoring mechanisms can help detect unauthorized modifications to D-Bus match rules. The vulnerability demonstrates the importance of maintaining up-to-date system components and highlights the risks associated with insufficient input validation in system-level services. Organizations should also consider implementing network segmentation and privilege separation techniques to limit the potential impact of such vulnerabilities, as outlined in various ATT&CK framework techniques related to privilege escalation and service manipulation. Regular security audits of system components and message bus configurations can help identify and remediate similar vulnerabilities before they can be exploited in real-world scenarios.