CVE-2020-9486 in NiFi
Summary
by MITRE • 10/04/2020
In Apache NiFi 1.10.0 to 1.11.4, the NiFi stateless execution engine produced log output which included sensitive property values. When a flow was triggered, the flow definition configuration JSON was printed, potentially containing sensitive values in plaintext.
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Analysis
by VulDB Data Team • 11/15/2020
Apache NiFi versions 1.10.0 through 1.11.4 contained a critical information disclosure vulnerability that exposed sensitive configuration data through log output mechanisms. This vulnerability specifically affected the stateless execution engine component which is designed for testing and development purposes but can be inadvertently activated in production environments. The flaw occurred when flows were triggered, causing the system to output detailed flow definition configuration data in json format to log files, thereby compromising sensitive property values that were previously protected within the application's configuration management system.
The technical implementation of this vulnerability stems from inadequate sanitization of log output within the stateless execution engine. When a flow was executed, the system automatically generated verbose logging that included the complete flow definition including any sensitive properties such as passwords, API keys, database credentials, or other confidential parameters. This behavior was particularly concerning because the stateless engine was intended for isolated testing scenarios but could be triggered in production environments, leading to unauthorized exposure of sensitive data. The vulnerability aligns with CWE-200, Information Exposure, and represents a classic case of insufficient logging output sanitization where system internals were exposed without proper access controls or data masking mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure to create significant security risks for organizations relying on Apache NiFi for data processing and integration. Attackers who gained access to log files or system monitoring tools could extract sensitive credentials and configuration parameters that would allow them to compromise downstream systems, access restricted data sources, or perform unauthorized operations within the NiFi environment. The plaintext exposure of sensitive values directly violates security best practices and could enable privilege escalation attacks, lateral movement within networks, and unauthorized access to critical infrastructure components. This vulnerability particularly affects organizations that do not maintain strict log file access controls or implement proper log sanitization policies, making it a high-risk issue for production deployments.
Organizations should immediately upgrade to Apache NiFi version 1.12.0 or later where this vulnerability has been addressed through improved log sanitization mechanisms. The mitigation strategy should include implementing comprehensive log file access controls, establishing proper log rotation and retention policies, and conducting regular security audits of log output configurations. Security teams should also implement monitoring solutions that can detect and alert on sensitive data exposure patterns within log files, using techniques aligned with ATT&CK framework's T1070.002 - Indicator Removal on Host. Additionally, organizations should review their overall configuration management practices to ensure that sensitive properties are properly masked or encrypted, and that stateless execution features are properly isolated from production environments to prevent unintended activation of vulnerable components.