CVE-2020-35340 in ExpertPDF
Summary
by MITRE • 09/15/2021
A local file inclusion vulnerability in ExpertPDF 9.5.0 through 14.1.0 allows attackers to read the file contents from files that the running ExpertPDF process has access to read.
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Analysis
by VulDB Data Team • 09/17/2021
The vulnerability identified as CVE-2020-35340 represents a critical local file inclusion flaw within ExpertPDF software versions ranging from 9.5.0 through 14.1.0. This vulnerability resides in the application's handling of file paths and input validation mechanisms, creating an exploitable condition where malicious actors can manipulate file access parameters to read arbitrary files accessible to the running ExpertPDF process. The flaw stems from inadequate sanitization of user-supplied input that is subsequently used to construct file paths, enabling attackers to traverse the file system and access sensitive data that should remain protected.
From a technical perspective, this vulnerability operates as a classic local file inclusion (LFI) attack vector where the application fails to properly validate or sanitize file path parameters before processing them. The flaw allows attackers to supply crafted input that bypasses normal access controls, potentially enabling them to read system configuration files, database credentials, application source code, or other sensitive information that the ExpertPDF service account has permission to access. The vulnerability is particularly concerning because it operates at the local file system level rather than through network protocols, making it difficult to detect through traditional network-based security measures.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially lead to privilege escalation and further system compromise. When the ExpertPDF process runs with elevated privileges or has access to sensitive system resources, attackers can leverage this vulnerability to extract confidential data, potentially including authentication credentials, encryption keys, or other critical system information. The vulnerability affects organizations that deploy ExpertPDF for document processing tasks, particularly those running the software with broad file system access permissions. This creates a significant risk for enterprise environments where document processing applications may have access to corporate data repositories or system configuration files.
Security professionals should consider this vulnerability in the context of CWE-22, which describes improper limitation of a pathname to a restricted directory, and its relationship to the broader ATT&CK framework under the technique T1083, File and Directory Discovery, and T1005, Data from Local System. Organizations should immediately apply vendor patches or updates to address this vulnerability, as the affected versions represent a substantial risk for unpatched systems. Additionally, implementing proper input validation, least privilege access controls for the ExpertPDF process, and regular security assessments can help mitigate the risk of exploitation. The vulnerability demonstrates the importance of proper input sanitization and access control mechanisms in preventing local file inclusion attacks, which remain a persistent threat vector in enterprise security environments.