CVE-2016-4216 in XMP Toolkit for Java
Summary
by MITRE
XMPCore in Adobe XMP Toolkit for Java before 5.1.3 allows remote attackers to read arbitrary files via XML data containing an external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
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Analysis
by VulDB Data Team • 02/23/2019
The vulnerability identified as CVE-2016-4216 represents a critical XML External Entity (XXE) flaw within Adobe XMP Toolkit for Java, specifically affecting versions prior to 5.1.3. This issue resides in the XMPCore component which processes XML metadata within Adobe's XMP (Extensible Metadata Platform) framework. The vulnerability stems from insufficient input validation and processing of XML data structures that contain external entity declarations, creating a pathway for malicious actors to exploit the system's XML parser configuration. The flaw manifests when the toolkit processes XML content that includes external entity references, allowing attackers to manipulate the parsing behavior and potentially access sensitive system resources.
The technical implementation of this vulnerability follows the classic XXE attack pattern where an attacker crafts malicious XML data containing external entity declarations that reference local files on the system. When the vulnerable XMP Toolkit processes such XML data, it fails to properly sanitize or restrict the parsing of external entities, enabling the XML parser to resolve these references and potentially read arbitrary files from the filesystem. This occurs because the toolkit's XML processing configuration does not adequately restrict access to external resources, allowing entity references to traverse the file system and retrieve content that should remain protected. The vulnerability is particularly concerning as it operates at the XML parsing layer, meaning that any application utilizing the affected toolkit could be susceptible to this attack vector regardless of its specific implementation.
The operational impact of CVE-2016-4216 extends beyond simple file disclosure, as it can potentially enable attackers to gain unauthorized access to sensitive metadata files, configuration data, or even system information that may be stored in accessible locations. This vulnerability affects Adobe's XMP Toolkit which is widely used across various Adobe products and third-party applications that rely on XMP metadata processing, amplifying the potential attack surface. The remote nature of this vulnerability means that attackers can exploit it without requiring local system access, making it particularly dangerous in web-facing applications or services that process user-provided XML content. This flaw aligns with CWE-611 (Improper Restriction of XML External Entity Reference) and represents a fundamental weakness in XML processing security controls that can lead to information disclosure, privilege escalation, or further attack chain exploitation.
Organizations affected by this vulnerability should prioritize immediate remediation through updating to Adobe XMP Toolkit version 5.1.3 or later, which includes proper XML entity validation and restriction mechanisms. Security measures should also include implementing XML parser configurations that disable external entity resolution entirely, particularly when processing untrusted input. Network-level protections such as web application firewalls and XML validation rules can provide additional defense-in-depth layers. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in XML processing, as outlined in various security frameworks including those referenced in the ATT&CK framework's data manipulation techniques. Regular security assessments of XML processing components and comprehensive testing of external entity handling should be implemented to prevent similar vulnerabilities from emerging in other systems.