CVE-2022-29265 in NiFi
Summary
by MITRE • 04/30/2022
Multiple components in Apache NiFi 0.0.1 to 1.16.0 do not restrict XML External Entity references in the default configuration. The Standard Content Viewer service attempts to resolve XML External Entity references when viewing formatted XML files. The following Processors attempt to resolve XML External Entity references when configured with default property values: - EvaluateXPath - EvaluateXQuery - ValidateXml Apache NiFi flow configurations that include these Processors are vulnerable to malicious XML documents that contain Document Type Declarations with XML External Entity references. The resolution disables Document Type Declarations in the default configuration for these Processors, and disallows XML External Entity resolution in standard services.
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Analysis
by VulDB Data Team • 05/04/2022
Apache NiFi versions 0.0.1 through 1.16.0 contain a critical vulnerability in their XML processing components that falls under the CWE-611 weakness category, specifically addressing insecure XML external entity processing. This vulnerability affects multiple core components including the Standard Content Viewer service and several processors such as EvaluateXPath, EvaluateXQuery, and ValidateXml. The flaw exists because these components do not properly restrict XML External Entity references in their default configurations, creating a pathway for malicious actors to exploit the system through carefully crafted XML documents.
The technical implementation of this vulnerability allows attackers to construct XML documents containing Document Type Declarations with XML External Entity references that can be processed by NiFi's default configurations. When these malicious documents are viewed or processed through the affected components, the system attempts to resolve the external entity references, potentially leading to information disclosure, denial of service, or even remote code execution depending on the underlying system configuration. The Standard Content Viewer service specifically demonstrates this behavior when attempting to format XML files, while the processors mentioned trigger the vulnerability through their default property values without requiring additional configuration changes.
The operational impact of this vulnerability is significant for organizations using Apache NiFi as their data processing platform, as it creates a persistent attack surface that can be exploited through various data ingestion points within the flow configuration. Attackers can leverage this vulnerability to perform server-side request forgery attacks, extract sensitive information from internal systems, or cause denial of service conditions by triggering resource exhaustion through malicious entity references. The default nature of the vulnerability means that organizations are at risk even when following standard installation procedures without explicit security hardening.
Security mitigations for this vulnerability include updating to Apache NiFi versions that have addressed the issue through proper XML external entity restriction, implementing explicit configuration changes that disable DTD processing and external entity resolution, and applying network-level restrictions to prevent access to internal resources from the NiFi environment. Organizations should also implement proper input validation and sanitization measures for XML content processed by NiFi, while monitoring for suspicious XML processing activities that might indicate exploitation attempts. The remediation aligns with ATT&CK technique T1213.002 for data from information repositories and T1059.007 for command and scripting interpreter, as attackers may attempt to leverage this vulnerability for information gathering and lateral movement within compromised environments.