CVE-2018-11640 in PowerMedia XMS
Summary
by MITRE
XML External Entity (XXE) vulnerability in the web service in Dialogic PowerMedia XMS before 3.5 SU2 allows remote attackers to read arbitrary files or cause a denial of service (resource consumption).
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Analysis
by VulDB Data Team • 02/24/2020
The CVE-2018-11640 vulnerability represents a critical XML External Entity processing flaw within Dialogic PowerMedia XMS web service components. This vulnerability exists in versions prior to 3.5 SU2 and exposes the system to remote exploitation by malicious actors who can manipulate XML parsing operations to access sensitive system resources. The flaw stems from insufficient input validation and sanitization within the web service's XML processing capabilities, creating an attack surface where external entity references can be leveraged for unauthorized data access and system disruption. The vulnerability specifically affects the web service interface that handles XML-based communication protocols, making it particularly dangerous in environments where the system processes external XML data from untrusted sources.
The technical implementation of this XXE vulnerability allows attackers to craft malicious XML requests that reference external entities hosted on remote servers or local file systems. When the web service processes these requests, it resolves external entity references without proper validation, enabling attackers to read arbitrary files from the system filesystem or access internal network resources. The vulnerability can also be exploited to cause resource exhaustion through malicious entity references that consume excessive system memory or processing power, leading to denial of service conditions. This exploitation capability aligns with CWE-611 which specifically addresses improper restriction of XML external entity references, and represents a direct violation of secure coding practices for XML processing. The attack vector operates over the network through the web service interface, requiring no local access or authentication credentials to initiate the exploit.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass significant system availability risks and potential data breaches. Remote attackers can leverage the XXE vulnerability to access sensitive configuration files, system credentials, and other confidential data stored on the affected system. The resource consumption aspect of the vulnerability can lead to complete system unavailability, particularly in environments where the web service handles high volumes of XML requests. Organizations utilizing Dialogic PowerMedia XMS in production environments face substantial risk exposure, as the vulnerability can be exploited by threat actors without requiring privileged access or sophisticated attack techniques. This makes the vulnerability particularly dangerous in enterprise environments where the system may be exposed to external networks or where it processes XML data from multiple untrusted sources. The impact is further compounded by the fact that the vulnerability affects the core web service functionality, potentially disrupting critical communication services that depend on the system.
Mitigation strategies for CVE-2018-11640 focus primarily on implementing proper XML parsing security measures and upgrading to patched versions of Dialogic PowerMedia XMS. Organizations should immediately upgrade to version 3.5 SU2 or later, which includes patches addressing the XXE vulnerability. System administrators should disable external entity resolution in XML parsers and implement strict input validation for all XML processing operations. Network segmentation and access controls should be enforced to limit exposure of the vulnerable web service to untrusted networks. Additionally, implementing web application firewalls and intrusion detection systems can help detect and prevent exploitation attempts. The remediation process should include comprehensive testing to ensure that XML processing operations no longer accept external entity references and that proper error handling is implemented to prevent information leakage. Security monitoring should be enhanced to detect unusual XML processing patterns that may indicate exploitation attempts, aligning with defensive strategies outlined in the mitre ATT&CK framework for web application vulnerabilities.