CVE-2018-3817 in Logstash
Summary
by MITRE
When logging warnings regarding deprecated settings, Logstash before 5.6.6 and 6.x before 6.1.2 could inadvertently log sensitive information.
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Analysis
by VulDB Data Team • 01/18/2020
The vulnerability identified as CVE-2018-3817 represents a critical information disclosure flaw within the Logstash data processing pipeline software. This issue affects versions prior to 5.6.6 and 6.x versions before 6.1.2, where the logging mechanism fails to properly sanitize deprecated configuration settings before outputting warning messages. The flaw arises from insufficient input validation and output filtering within the logging subsystem, creating potential exposure of sensitive data that administrators might not intend to be publicly visible.
The technical implementation of this vulnerability stems from how Logstash handles deprecated settings during the configuration validation process. When the system encounters deprecated parameters in configuration files, it generates warning messages that include the actual values of these settings. This behavior creates a scenario where sensitive information such as passwords, API keys, database credentials, or other confidential data could be inadvertently included in log files or console output. The issue is particularly concerning because logging is a fundamental component of system monitoring and troubleshooting, making log files prime targets for unauthorized access and analysis.
From an operational impact perspective, this vulnerability significantly increases the attack surface for systems running affected Logstash versions. Security researchers and malicious actors can exploit this flaw to extract sensitive credentials from log files, potentially leading to unauthorized access to backend systems, databases, or cloud services. The vulnerability aligns with CWE-200, which addresses "Information Exposure," and specifically relates to CWE-532, "Information Exposure Through Log Files." The exposure of sensitive information through log files can result in cascading security incidents, including privilege escalation, data breaches, and unauthorized system access.
The exploitation of this vulnerability typically requires an attacker to have access to the system's log files or monitoring infrastructure where Logstash warnings are displayed. This could occur through compromised user accounts, misconfigured access controls, or through legitimate system administration access that is not properly secured. The ATT&CK framework categorizes this vulnerability under T1070.004, "Indicator Removal on Host: File Deletion," as attackers may need to manipulate log files to cover their tracks or extract sensitive information. Additionally, the technique T1566.001 "Phishing: Spearphishing Attachment" could be relevant if attackers craft malicious configurations to trigger these warnings and then harvest sensitive data from the resulting logs.
Organizations should immediately implement mitigations including updating to the patched versions of Logstash, specifically 5.6.6 or 6.1.2 and later. System administrators should also review existing log files for any exposed sensitive information and implement proper log sanitization policies. The remediation process should include configuring Logstash to avoid logging sensitive data in warning messages, implementing strict access controls on log files, and establishing monitoring procedures to detect potential information exposure incidents. Security teams should conduct thorough log reviews to identify any previously exposed credentials and ensure that deprecated settings are properly handled without compromising system security.