CVE-2015-5619 in Logstash
Summary
by MITRE
Logstash 1.4.x before 1.4.5 and 1.5.x before 1.5.4 with Lumberjack output or the Logstash forwarder does not validate SSL/TLS certificates from the Logstash server, which might allow attackers to obtain sensitive information via a man-in-the-middle attack.
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Analysis
by VulDB Data Team • 06/13/2022
The vulnerability described in CVE-2015-5619 represents a critical security flaw in the Logstash data processing pipeline that affected versions 1.4.x prior to 1.4.5 and 1.5.x prior to 1.5.4. This issue specifically impacts the Lumberjack output plugin and the Logstash forwarder components, which are designed to securely transmit log data from remote systems to central Logstash servers. The flaw stems from inadequate SSL/TLS certificate validation mechanisms that leave the communication channel susceptible to man-in-the-middle attacks, potentially allowing malicious actors to intercept and access sensitive log data during transmission.
The technical implementation of this vulnerability resides in the cryptographic validation layer of the Lumberjack protocol implementation within Logstash. When the Logstash forwarder attempts to establish a secure connection with the Logstash server, the system fails to properly verify the server's SSL/TLS certificate against trusted certificate authorities. This validation failure occurs at the transport layer security handshake process, where the forwarder should be performing certificate chain validation, hostname verification, and trust anchor checking. The absence of these critical validation steps creates an attack surface where an adversary positioned within the network can perform SSL/TLS stripping attacks or present fraudulent certificates to establish false connections.
From an operational perspective, this vulnerability poses significant risks to organizations relying on Logstash for log aggregation and monitoring. The potential impact includes unauthorized access to sensitive operational data, including system logs, application logs, and potentially confidential information processed through the logging infrastructure. Attackers could exploit this weakness to capture credentials, system configurations, network traffic patterns, and other valuable data that flows through the Logstash pipeline. The vulnerability is particularly dangerous in environments where log data contains personally identifiable information, financial data, or other regulated information that requires protection under various compliance frameworks.
The attack vector for this vulnerability aligns with the tactics described in the MITRE ATT&CK framework under the initial access and credential access domains, specifically targeting the network infrastructure components. This weakness enables adversaries to establish persistent monitoring capabilities while remaining undetected within the network. Organizations implementing the affected Logstash versions face a heightened risk of data exfiltration and reconnaissance activities that could compromise their overall security posture. The vulnerability also violates fundamental security principles outlined in NIST SP 800-53 and ISO 27001 standards, particularly those related to secure communication and cryptographic key management.
Mitigation strategies for CVE-2015-5619 should prioritize immediate version upgrades to Logstash 1.4.5 or 1.5.4, respectively, which contain the necessary certificate validation fixes. Organizations should also implement additional network-level security controls such as firewall rules to restrict access to Logstash servers, deployment of network segmentation to isolate logging infrastructure, and monitoring for unusual connection patterns that might indicate certificate validation failures. Security teams should conduct comprehensive vulnerability assessments of their logging infrastructure and ensure that all components maintain proper certificate validation mechanisms. Additionally, implementing certificate pinning techniques and regular certificate rotation policies can provide additional layers of protection against similar vulnerabilities in the future, while adhering to industry best practices for secure configuration management and cryptographic implementation standards.