CVE-2019-19702 in modoboa-dmarc Plugin
Summary
by MITRE
The modoboa-dmarc plugin 1.1.0 for Modoboa is vulnerable to an XML External Entity Injection (XXE) attack when processing XML data. A remote attacker could exploit this to perform a denial of service against the DMARC reporting functionality, such as by referencing the /dev/random file within XML documents that are emailed to the address in the rua field of the DMARC records of a domain.
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Analysis
by VulDB Data Team • 03/10/2024
The modoboa-dmarc plugin version 1.1.0 presents a critical security vulnerability classified as XML External Entity Injection (XXE) under CWE-611, which fundamentally compromises the integrity and availability of DMARC reporting functionality within the Modoboa email management platform. This vulnerability specifically affects the processing of XML data received through email notifications, creating an attack surface that allows malicious actors to manipulate the system's XML parser behavior. The flaw exists in how the plugin handles incoming DMARC reports that contain XML content, particularly when these reports are directed to email addresses specified in the rua field of DMARC records, making it a significant concern for organizations relying on email security monitoring.
The technical implementation of this XXE vulnerability enables remote attackers to inject malicious XML entities that reference local system resources, including sensitive files like /dev/random, which can be exploited to consume system resources and cause denial of service conditions. When the plugin processes XML documents containing external entity references, the XML parser automatically resolves these references, potentially leading to information disclosure, server-side request forgery, or resource exhaustion attacks. The attack vector specifically targets the DMARC reporting mechanism where email notifications containing XML data are automatically processed, creating a direct pathway for exploitation without requiring authentication or privileged access within the system.
The operational impact of this vulnerability extends beyond simple denial of service, as it fundamentally undermines the reliability of email security monitoring capabilities that organizations depend upon for threat detection and response. Organizations using modoboa-dmarc plugin version 1.1.0 may experience disruption to their email security infrastructure when malicious actors exploit this weakness to flood the system with resource-intensive XML processing requests. The vulnerability aligns with ATT&CK technique T1213.002 for Data from Information Repositories and T1499.004 for Endpoint Denial of Service, representing both information gathering and availability compromise attack patterns that can significantly impact email security operations and incident response capabilities.
Mitigation strategies for this XXE vulnerability should focus on implementing proper XML parser configuration to disable external entity resolution and parameter entity expansion. Organizations should immediately upgrade to a patched version of the modoboa-dmarc plugin where available, as this represents the most effective immediate solution to prevent exploitation. Additional protective measures include implementing strict input validation for XML content, configuring network-level restrictions to prevent unauthorized access to internal system resources, and monitoring email traffic for suspicious XML content patterns. The vulnerability also underscores the importance of applying security patches promptly and maintaining updated security configurations, particularly for plugins and modules that process external data from untrusted sources. Organizations should consider implementing web application firewalls and intrusion detection systems to monitor for potential exploitation attempts and establish incident response procedures to address successful attacks against email security infrastructure components.