CVE-2019-7619 in Elasticsearch
Summary
by MITRE
Elasticsearch versions 7.0.0-7.3.2 and 6.7.0-6.8.3 contain a username disclosure flaw was found in the API Key service. An unauthenticated attacker could send a specially crafted request and determine if a username exists in the Elasticsearch native realm.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 10/31/2019
The vulnerability identified as CVE-2019-7619 represents a critical information disclosure flaw within the Elasticsearch API Key service that affects multiple versions including 7.0.0 through 7.3.2 and 6.7.0 through 6.8.3. This vulnerability stems from improper handling of authentication requests within the native realm authentication system, specifically exposing sensitive information about user accounts without requiring valid credentials or authentication. The flaw operates at the application layer and demonstrates a classic security misconfiguration that violates fundamental principles of access control and authentication security.
The technical implementation of this vulnerability allows an unauthenticated attacker to exploit a timing difference in the API Key service response behavior. When a request is made to check for a specific username that exists in the Elasticsearch native realm, the system responds with a different timing pattern compared to when the username does not exist. This timing-based side-channel information leakage enables attackers to perform username enumeration attacks against the Elasticsearch instance. The vulnerability is classified under CWE-200 as "Information Exposure" and specifically relates to CWE-359 "Exposure of Private Information ('Privacy Violation')". This type of information disclosure directly violates the principle of least privilege and can significantly aid attackers in planning subsequent exploitation phases.
The operational impact of this vulnerability extends beyond simple information disclosure as it provides attackers with a crucial reconnaissance capability that can be leveraged in broader attack campaigns. By enumerating valid usernames, attackers can target specific accounts for password spraying, credential stuffing, or social engineering attacks. The vulnerability affects Elasticsearch installations that utilize the native realm authentication mechanism, which is the default authentication method for many deployments. This makes the impact particularly widespread across organizations that have not implemented additional authentication layers or network segmentation. The timing-based nature of the vulnerability means that it can be exploited through automated tools and scripts, making it a significant concern for organizations with publicly accessible Elasticsearch instances.
Organizations should implement immediate mitigations including upgrading to Elasticsearch versions 7.4.0 or 6.8.4 which contain the fix for this vulnerability. Network segmentation and access control measures should be enforced to limit exposure of Elasticsearch instances to untrusted networks. Additional protective measures include implementing rate limiting and monitoring for unusual authentication patterns that may indicate enumeration attempts. The vulnerability aligns with ATT&CK technique T1078.004 "Valid Accounts: Cloud Accounts" and T1565.001 "Data Manipulation: Stored Data Manipulation" as it enables attackers to establish persistent access through valid account enumeration and potentially manipulate stored data through subsequent exploitation. Security monitoring should be enhanced to detect timing-based request patterns that indicate username enumeration attempts, as this vulnerability represents a significant risk to authentication security and can facilitate more sophisticated attacks against the Elasticsearch environment.