CVE-2018-12914 in PublicCMS
Summary
by MITRE
A remote code execution issue was discovered in PublicCMS V4.0.20180210. An attacker can upload a ZIP archive that contains a .jsp file with a directory traversal pathname. After an unzip operation, the attacker can execute arbitrary code by visiting a .jsp URI.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability CVE-2018-12914 represents a critical remote code execution flaw in PublicCMS version 4.0.20180210 that stems from inadequate input validation during file upload operations. This vulnerability falls under the category of directory traversal attacks and specifically targets the application's decompression functionality. The flaw allows malicious actors to bypass security controls by crafting specially formatted ZIP archives containing JSP files with directory traversal sequences in their filenames. The vulnerability is classified as CWE-22 under the CWE top 25 list, which specifically addresses improper limitation of a pathname to a restricted directory, also known as path traversal or directory traversal. This weakness enables attackers to access files and directories outside the intended scope of the application's file system access.
The technical implementation of this vulnerability occurs during the unzipping process when the application fails to properly sanitize or validate the file paths contained within the ZIP archive. When a malicious ZIP file is uploaded and subsequently extracted, the directory traversal sequences in the .jsp filenames allow the attacker to place executable code in locations outside the intended web root directory. This creates a scenario where the application's decompression logic does not adequately check for relative path references such as '../' or similar traversal patterns that would normally be rejected by proper input validation. The vulnerability is particularly dangerous because it leverages the legitimate unzip functionality of the application, making the attack vector appear benign and increasing the likelihood of successful exploitation. The ATT&CK framework categorizes this as a technique under T1059.007 for "Command and Scripting Interpreter: JavaScript', where the attacker uses JSP files to execute arbitrary commands on the server.
The operational impact of this vulnerability is severe and encompasses multiple attack vectors that can lead to complete system compromise. Once successfully exploited, an attacker gains the ability to execute arbitrary code with the privileges of the web application, potentially leading to full system control, data exfiltration, and persistence mechanisms. The vulnerability affects the application's file upload functionality and can be exploited remotely without requiring authentication, making it particularly dangerous for publicly accessible web applications. Organizations running PublicCMS versions prior to the patched release face significant risk of unauthorized access, data breaches, and potential lateral movement within their network infrastructure. The attack requires minimal technical skill to execute, as it relies on standard file upload and directory traversal techniques that are well-documented and commonly available in exploit frameworks.
Mitigation strategies for CVE-2018-12914 should focus on immediate patching of the affected PublicCMS version to the latest secure release that addresses the directory traversal vulnerability in the decompression logic. Organizations should implement strict input validation for all file upload operations, including comprehensive path sanitization that rejects any filenames containing directory traversal sequences. Network segmentation and web application firewalls should be configured to monitor and block suspicious file upload patterns and directory traversal attempts. The implementation of principle of least privilege should be enforced for web application accounts, limiting the potential damage from successful exploitation. Additionally, organizations should conduct regular security assessments of their web applications to identify similar vulnerabilities in file handling and decompression functions. The vulnerability also highlights the importance of secure coding practices around file system operations and the necessity of validating all user-supplied input before processing, particularly in applications that handle untrusted file uploads. Regular security updates and patch management processes should be implemented to prevent similar vulnerabilities from being introduced in future versions of the software.