CVE-2019-7620 in Logstash
Summary
by MITRE
Logstash versions before 7.4.1 and 6.8.4 contain a denial of service flaw in the Logstash Beats input plugin. An unauthenticated user who is able to connect to the port the Logstash beats input could send a specially crafted network packet that would cause Logstash to stop responding.
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Analysis
by VulDB Data Team • 10/31/2019
The vulnerability identified as CVE-2019-7620 represents a critical denial of service flaw within the Logstash Beats input plugin affecting versions prior to 7.4.1 and 6.8.4. This issue stems from insufficient input validation mechanisms within the Beats input plugin that processes incoming network data from Beats agents, which are lightweight data shippers used to forward logs and events to Logstash. The flaw exists in the plugin's handling of malformed network packets, specifically those that exploit improper buffer management and parsing routines when processing incoming data streams.
The technical implementation of this vulnerability allows an attacker to exploit the Logstash Beats input plugin through network-based attacks that do not require authentication credentials. When a malicious actor sends specially crafted network packets to the Logstash port configured to accept Beats input, the system's processing logic fails to properly handle the malformed data structures, leading to resource exhaustion or memory corruption that ultimately causes Logstash to become unresponsive and cease processing legitimate network traffic. This behavior aligns with CWE-400 vulnerability classification related to resource exhaustion and represents a classic denial of service attack vector that can be executed remotely.
From an operational impact perspective, this vulnerability poses significant risks to organizations relying on Logstash for log aggregation and security monitoring. The unauthenticated nature of the attack means that any network entity capable of reaching the Logstash server's Beats input port could trigger the service disruption, potentially affecting critical security operations and incident response capabilities. The attack can be executed with minimal resources and technical expertise, making it particularly dangerous for environments where Logstash serves as a central component of security infrastructure. The service disruption directly impacts the availability of log processing capabilities, which can compromise security monitoring, compliance reporting, and operational visibility.
The mitigation strategy for CVE-2019-7620 involves immediate deployment of patched Logstash versions 7.4.1 or 6.8.4, which contain proper input validation and buffer management controls. Organizations should also implement network segmentation and access controls to restrict direct connectivity to Logstash Beats input ports, utilizing firewalls or network access control lists to limit exposure. Additionally, monitoring and alerting should be configured to detect unusual network patterns or service disruptions that might indicate exploitation attempts. The remediation aligns with ATT&CK technique T1499.004 for network denial of service and emphasizes the importance of keeping security infrastructure components up to date. Network administrators should also consider implementing intrusion detection systems that can identify and block malformed network packets targeting known vulnerable ports, while conducting regular vulnerability assessments to ensure comprehensive protection against similar threats.