CVE-2019-3821 in RGW Server
Summary
by MITRE
A flaw was found in the way civetweb frontend was handling requests for ceph RGW server with SSL enabled. An unauthenticated attacker could create multiple connections to ceph RADOS gateway to exhaust file descriptors for ceph-radosgw service resulting in a remote denial of service.
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Analysis
by VulDB Data Team • 11/19/2024
The vulnerability identified as CVE-2019-3821 resides within the civetweb frontend implementation used by the ceph RADOS gateway service when operating with SSL encryption enabled. This flaw represents a significant security weakness in distributed storage systems that could be exploited to disrupt service availability. The ceph RADOS gateway serves as a crucial component for providing S3-compatible object storage interfaces, making this vulnerability particularly concerning for organizations relying on ceph storage clusters for critical data operations. The issue manifests specifically when the service handles incoming requests through the civetweb web server framework that is integrated into the ceph RGW implementation.
The technical root cause of this vulnerability stems from inadequate resource management within the civetweb component when processing SSL-enabled requests. An attacker can exploit this weakness by establishing multiple concurrent connections to the ceph RGW service without authentication, causing the service to consume all available file descriptors. This occurs because the implementation fails to properly limit or manage the number of concurrent connections that can be established, particularly in the SSL context where connection setup involves additional overhead and resource allocation. The flaw operates at the protocol handling layer where the web server framework does not enforce proper connection limits or resource cleanup mechanisms, allowing malicious actors to systematically exhaust the service's available file descriptor pool.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire storage infrastructure availability. When the ceph-radosgw service exhausts its file descriptors, it becomes unable to accept new connections or process existing requests, effectively rendering the object storage interface inaccessible to legitimate users. This denial of service condition can persist until the service is manually restarted or the system resources are manually cleared, creating potential downtime that could affect business operations depending on the storage infrastructure's criticality. Organizations using ceph clusters for production workloads face significant risk of service interruptions that could cascade into broader operational impacts.
This vulnerability aligns with CWE-400, which addresses "Uncontrolled Resource Consumption" and represents a classic resource exhaustion attack pattern. The flaw demonstrates characteristics consistent with the attack pattern described in the MITRE ATT&CK framework under the technique T1499.004 for "Endpoint Denial of Service" where attackers target specific service resources to cause availability disruption. Organizations should implement connection rate limiting and resource monitoring to detect anomalous connection patterns that could indicate exploitation attempts. The recommended mitigations include upgrading to patched versions of ceph that address the civetweb resource management issues, implementing proper connection limits at the network level, and deploying monitoring solutions that can detect file descriptor exhaustion patterns. Additionally, organizations should consider implementing authentication requirements for the ceph RGW service where possible, as the vulnerability specifically targets unauthenticated connections, thereby reducing the attack surface through proper access controls and network segmentation.