CVE-2016-0882 in Documentum xCP
Summary
by MITRE
EMC Documentum xCP 2.1 before patch 23 and 2.2 before patch 11 allows remote authenticated users to read arbitrary files via a POST request containing an XML 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 • 07/08/2022
The vulnerability identified as CVE-2016-0882 represents a critical XML External Entity (XXE) flaw affecting EMC Documentum xCP versions 2.1 prior to patch 23 and 2.2 prior to patch 11. This issue falls under the Common Weakness Enumeration category CWE-611, which specifically addresses Improper Restriction of XML External Entity Reference. The vulnerability stems from insufficient input validation within the document management system's XML processing capabilities, creating an avenue for malicious exploitation by authenticated remote attackers.
The technical exploitation mechanism involves crafting a specially formatted POST request that includes an XML external entity declaration followed by an entity reference. When the vulnerable system processes this malformed XML input, it inadvertently resolves external entity references, allowing attackers to access arbitrary files on the server filesystem. This occurs because the application fails to properly sanitize XML input and does not restrict access to external resources during XML parsing operations. The XXE vulnerability specifically targets the XML parser's handling of external entities, enabling attackers to perform file inclusion attacks and potentially gain unauthorized access to sensitive system information.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the capability to read arbitrary files from the affected system. This could include configuration files, database connection details, user credentials, or other sensitive data stored on the server. The authenticated nature of the attack means that an attacker must first obtain valid credentials, but this still represents a significant security risk as it allows for privilege escalation and lateral movement within the network. The vulnerability affects the core document management functionality of the xCP platform, potentially compromising thousands of documents and associated metadata that are processed through the vulnerable XML parsing components.
Organizations affected by this vulnerability should immediately implement patches provided by EMC to address the XXE issue in their Documentum xCP installations. The mitigation strategy should include comprehensive input validation for all XML processing components and the implementation of strict XML parser configurations that disable external entity resolution. Security teams should also conduct thorough vulnerability assessments to identify any other potential XXE vulnerabilities within their Documentum environment and related systems. Additionally, network segmentation and access controls should be reviewed to limit the potential impact of successful exploitation attempts. This vulnerability aligns with ATT&CK technique T1059.007 for XML External Entity Processing, emphasizing the need for proper input validation and secure coding practices to prevent unauthorized file access through XML parsing mechanisms.