CVE-2013-4130 in SPICE
Summary
by MITRE
The (1) red_channel_pipes_add_type and (2) red_channel_pipes_add_empty_msg functions in server/red_channel.c in SPICE before 0.12.4 do not properly perform ring loops, which might allow remote attackers to cause a denial of service (reachable assertion and server exit) by triggering a network error.
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Analysis
by VulDB Data Team • 01/04/2022
The vulnerability identified as CVE-2013-4130 affects the SPICE (Simple Protocol for Independent Computing Environments) server implementation prior to version 0.12.4. This issue resides in the server/red_channel.c file where two specific functions red_channel_pipes_add_type and red_channel_pipes_add_empty_msg fail to correctly handle ring buffer operations. The flaw manifests when these functions process network error conditions, creating a scenario where the server's internal ring loop mechanisms become compromised. This represents a critical security weakness in the remote desktop virtualization protocol that could be exploited by malicious actors to disrupt service availability.
The technical implementation of this vulnerability stems from improper handling of circular buffer operations within the SPICE server's channel management system. When network errors occur during communication between the SPICE server and client, the affected functions do not correctly maintain the ring buffer state, leading to assertion failures that cause the server process to terminate unexpectedly. The ring loop mechanism in question is designed to manage data flow between different communication channels, but the flawed implementation fails to account for error conditions properly. This issue falls under the CWE-691 category of Insufficient Control Flow Management, specifically involving improper handling of circular buffer operations and control flow during error conditions.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise the entire SPICE server infrastructure. Remote attackers can exploit this weakness by crafting specific network error conditions that trigger the flawed ring loop handling, resulting in server crashes and complete service unavailability. The vulnerability affects virtualization environments that rely on SPICE for remote desktop access, particularly in cloud computing and enterprise virtualization deployments. The consequences include extended downtime for virtual desktop infrastructure, potential loss of user sessions, and disruption of business-critical applications that depend on SPICE-based remote access solutions. This weakness aligns with ATT&CK technique T1499.004 for Network Denial of Service, where adversaries exploit protocol implementation flaws to disrupt service availability.
Mitigation strategies for CVE-2013-4130 primarily involve immediate patching of SPICE server installations to version 0.12.4 or later, which contains the necessary fixes for proper ring buffer handling. Organizations should also implement network monitoring to detect unusual error patterns that might indicate exploitation attempts, and establish robust failover mechanisms to minimize service disruption during potential attacks. Additional defensive measures include implementing network segmentation to limit exposure, configuring intrusion detection systems to monitor for characteristic error patterns, and maintaining regular security assessments of virtualization environments. The fix addresses the root cause by ensuring proper ring loop management during error conditions, preventing the assertion failures that previously caused server termination. This vulnerability highlights the importance of thorough testing of error handling mechanisms in network protocols and demonstrates how seemingly minor implementation flaws can result in significant service disruption.