CVE-2019-12154 in PDFreactor
Summary
by MITRE
XXE in the XML parser library in RealObjects PDFreactor before 10.1.10722 allows attackers to supply malicious XML content in externally referenced resources, leading to disclosure of local file contents and/or denial of service conditions.
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Analysis
by VulDB Data Team • 06/22/2020
The vulnerability identified as CVE-2019-12154 represents a critical XML External Entity (XXE) flaw within the RealObjects PDFreactor library's XML parser implementation. This vulnerability affects versions prior to 10.1.10722 and exposes systems to significant security risks through improper handling of external entity references in XML processing. The flaw enables attackers to manipulate XML parsing operations by introducing malicious external resources that can trigger unauthorized access to local system files and potentially disrupt service availability.
The technical implementation of this vulnerability stems from insufficient validation and sanitization of XML external entity declarations within the PDFreactor library. When the XML parser encounters external entity references in processed documents, it fails to properly restrict access to local resources, allowing attackers to craft malicious XML content that references local files or network resources. This behavior directly violates the principles of secure XML processing and represents a classic XXE attack vector. The vulnerability is classified under CWE-611, which specifically addresses Improper Restriction of XML External Entity Reference, and aligns with ATT&CK technique T1213.002 for Data from Information Repositories, as it enables unauthorized data access through XML processing mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure to include potential denial of service conditions that can severely impact system availability. Attackers can exploit this flaw to access sensitive local files, potentially including system configuration data, user credentials, or proprietary documents stored on the server. The ability to trigger denial of service through malformed XML processing can also disrupt business operations and compromise system reliability. Additionally, the vulnerability may enable attackers to perform server-side request forgery attacks by leveraging the XML parser's ability to access external resources, potentially allowing them to probe internal networks or access restricted services.
Mitigation strategies for CVE-2019-12154 should prioritize immediate patching of affected systems to version 10.1.10722 or later, which includes proper XML external entity validation and restriction mechanisms. Organizations should implement comprehensive XML input validation and sanitization procedures, ensuring that all external entity references are properly restricted or disabled within XML processing pipelines. Security configurations should enforce strict XML parser settings that prevent loading of external entities and DTD references. Network segmentation and access controls should be implemented to limit exposure of systems running PDFreactor to trusted networks only. Additionally, regular security assessments and vulnerability scanning should be conducted to identify and remediate similar XXE vulnerabilities in other XML processing components throughout the organization's infrastructure.