CVE-2016-5009 in Ceph
Summary
by MITRE
The handle_command function in mon/Monitor.cc in Ceph allows remote authenticated users to cause a denial of service (segmentation fault and ceph monitor crash) via an (1) empty or (2) crafted prefix.
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Analysis
by VulDB Data Team • 09/02/2022
The vulnerability identified as CVE-2016-5009 resides within the Ceph storage system's monitoring component, specifically in the handle_command function located in mon/Monitor.cc. This flaw represents a critical denial of service vulnerability that can be exploited by remotely authenticated attackers to crash the ceph monitor service. The issue stems from insufficient input validation within the command handling mechanism, where the system fails to properly process empty or malformed command prefixes. Ceph monitors form the core of the distributed storage system's coordination and consensus mechanisms, making their stability crucial for overall system integrity. When an attacker crafts a malicious command with an empty prefix or a specially crafted prefix, the system's command processing logic encounters an unexpected state that leads to a segmentation fault and subsequent service crash.
The technical implementation of this vulnerability demonstrates a classic buffer over-read or improper input handling flaw that falls under CWE-125, which describes out-of-bounds read conditions. The handle_command function lacks proper validation of command prefix parameters, allowing attackers to pass malformed inputs that cause the monitor process to access memory locations outside the intended buffer boundaries. This type of vulnerability is particularly dangerous in distributed systems like Ceph because it can be exploited to create cascading failures across the storage cluster. The attacker does not require privileged access beyond authentication credentials, making this vector particularly concerning for production environments where multiple users may have legitimate access to the system. The attack can be executed through the standard Ceph monitoring interfaces, making it difficult to distinguish from legitimate administrative commands.
The operational impact of CVE-2016-5009 extends beyond simple service disruption, as ceph monitor crashes can lead to cluster instability and potential data availability issues. When a monitor process crashes, the distributed consensus mechanism that maintains cluster state information becomes compromised, potentially leading to split-brain scenarios or temporary unavailability of storage services. The vulnerability affects the entire Ceph monitoring infrastructure, as all monitor nodes are susceptible to the same flaw, creating a significant risk for high-availability deployments. From an attacker perspective, this represents a low-effort, high-impact vector that can be automated and deployed at scale against vulnerable systems. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, as the exploitation results in service unavailability that can be leveraged to disrupt business operations.
Mitigation strategies for CVE-2016-5009 should focus on immediate patching of affected Ceph versions, with administrators prioritizing updates to versions that contain the fix for the handle_command function. Network segmentation and access control measures can help limit the attack surface by restricting which authenticated users can submit commands to the monitor services. Implementing monitoring and alerting for unexpected monitor process crashes can help detect exploitation attempts and provide early warning of potential attacks. Additionally, input validation should be strengthened at multiple layers of the system to prevent malformed command prefixes from reaching the vulnerable function. The fix typically involves adding proper boundary checks and input sanitization before processing command prefixes, ensuring that empty or malformed inputs are handled gracefully rather than causing process termination. Organizations should also consider implementing redundant monitor configurations and automated failover mechanisms to reduce the impact of any successful exploitation attempts.