CVE-2018-12939 in SeedDMS
Summary
by MITRE
A directory traversal flaw in SeedDMS (formerly LetoDMS and MyDMS) before 5.1.8 allows an authenticated attacker to write to (or potentially delete) arbitrary files via a .. (dot dot) in the "op/op.UploadChunks.php" "qquuid" parameter. NOTE: this can be leveraged to execute arbitrary code by using CVE-2018-12940.
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability CVE-2018-12939 represents a critical directory traversal flaw within SeedDMS, a document management system that has undergone several name changes from LetoDMS to MyDMS and finally to SeedDMS. This vulnerability affects versions prior to 5.1.8 and specifically targets the file upload functionality within the system. The flaw manifests in the op/op.UploadChunks.php component where the qquuid parameter fails to properly sanitize user input, creating an opportunity for attackers to manipulate file paths through directory traversal sequences. The vulnerability is particularly concerning because it requires only authentication to exploit, meaning that any authenticated user with access to the system can potentially leverage this flaw. This represents a significant security risk as it allows attackers to write to arbitrary files on the server filesystem, potentially leading to complete system compromise. The vulnerability operates at the application layer and specifically targets the file handling mechanisms within the document management system, making it a prime candidate for privilege escalation and lateral movement within compromised environments.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the qquuid parameter processing. When an attacker submits a crafted qquuid value containing directory traversal sequences such as .. or similar path manipulation techniques, the application fails to properly validate or sanitize these inputs before using them in file operations. This lack of proper input validation creates a path traversal condition that allows the application to interpret the malicious input as a legitimate file path, enabling attackers to navigate outside of intended directories and access or modify files that should remain protected. The vulnerability operates under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. This weakness allows attackers to access files and directories that are stored outside of the web root directory, potentially leading to unauthorized data access, modification, or deletion. The flaw essentially bypasses the intended file access controls and allows for arbitrary file system operations.
The operational impact of this vulnerability extends far beyond simple file manipulation, as it can be leveraged to achieve arbitrary code execution through the exploitation of CVE-2018-12940. An authenticated attacker can use this directory traversal capability to upload malicious files to critical system locations, potentially including web root directories or system configuration files. The implications are severe as this could enable attackers to establish persistent access, install backdoors, or modify core system components. The vulnerability's exploitation requires minimal privileges, making it particularly dangerous in environments where users have legitimate access to the document management system. Attackers could potentially use this flaw to gain unauthorized access to sensitive documents, modify system configurations, or even execute commands on the underlying operating system. This vulnerability also aligns with ATT&CK technique T1059, which covers command and scripting interpreter, as the ability to write arbitrary files can lead to execution of malicious code. The compromise of file upload mechanisms can lead to complete system compromise, especially when combined with other vulnerabilities or techniques.
Mitigation strategies for CVE-2018-12939 should focus on immediate patching of the affected SeedDMS versions to 5.1.8 or later, which contains the necessary fixes for the directory traversal vulnerability. Organizations should implement strict input validation and sanitization measures for all file upload parameters, ensuring that path traversal sequences are properly rejected or encoded. The system should enforce proper file access controls and implement a least privilege model for file operations, preventing users from writing to critical system directories. Network segmentation and monitoring should be implemented to detect anomalous file access patterns or unauthorized file modifications. Additionally, organizations should conduct regular security assessments of their document management systems, implement web application firewalls to filter malicious requests, and establish secure coding practices that prevent similar vulnerabilities from being introduced in future development cycles. The remediation process should also include comprehensive testing to ensure that the patch does not introduce any regressions in system functionality while properly addressing the directory traversal vulnerability.