CVE-2007-4570 in mcstrans
Summary
by MITRE
Algorithmic complexity vulnerability in the MCS translation daemon in mcstrans 0.2.3 allows local users to cause a denial of service (temporary daemon outage) via a large range of compartments in sensitivity labels.
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Analysis
by VulDB Data Team • 07/30/2019
The vulnerability identified as CVE-2007-4570 represents a critical algorithmic complexity issue within the mcstrans daemon component of the mcstrans package version 0.2.3. This daemon serves as a translation service for Multi-Category Security (MCS) labels within SELinux environments, facilitating the conversion of sensitivity labels into human-readable formats. The flaw manifests specifically in the handling of compartment ranges within sensitivity labels, where the daemon fails to properly manage computational complexity when processing extensive compartment specifications.
The technical implementation of this vulnerability stems from the daemon's inefficient algorithmic approach to processing compartment data structures. When local users submit sensitivity labels containing large ranges of compartments, the mcstrans daemon experiences exponential growth in processing time and resource consumption. This occurs because the underlying algorithm lacks proper bounds checking and optimization for handling extensive compartment ranges, leading to what is classified as a time complexity explosion. The vulnerability operates at the application layer and requires local system access, making it a local privilege escalation vector that can be exploited by users with minimal system privileges.
From an operational impact perspective, this vulnerability creates a significant availability risk for systems relying on mcstrans for MCS label translation services. The denial of service condition manifests as temporary daemon outages that can disrupt security policy enforcement and system monitoring capabilities. Organizations using SELinux with MCS configurations face potential operational disruptions when the daemon becomes unresponsive due to malformed compartment specifications. The impact extends beyond simple service interruption as it can affect the broader security infrastructure, potentially leaving systems vulnerable during the daemon outage period and impacting the integrity of security label processing.
The vulnerability aligns with CWE-770, which addresses allocation of resources without limits or with inadequate limits, and demonstrates characteristics consistent with the ATT&CK technique T1499.004 for network denial of service attacks. The exploitability of this vulnerability requires local access and involves crafting specific sensitivity labels with extensive compartment ranges, making it a low-effort but high-impact vector for service disruption. Security practitioners should consider this vulnerability as part of broader system hardening efforts, particularly in environments where SELinux MCS policies are actively deployed and monitored.
Mitigation strategies for CVE-2007-4570 should focus on immediate patching of the mcstrans package to version 0.2.4 or later, which includes algorithmic improvements and proper bounds checking for compartment range processing. System administrators should implement monitoring for unusual daemon behavior and consider implementing resource limits on the mcstrans daemon to prevent complete service exhaustion. Additionally, organizations should review their SELinux policy configurations to minimize the use of extensive compartment ranges in sensitivity labels, reducing the attack surface for this specific vulnerability. Network segmentation and access controls should be implemented to limit local user access to systems running mcstrans, particularly in environments where the daemon is exposed to untrusted local users.