CVE-2021-40887 in ProjectSend
Summary
by MITRE • 10/11/2021
Projectsend version r1295 is affected by a directory traversal vulnerability. Because of lacking sanitization input for files[] parameter, an attacker can add ../ to move all PHP files or any file on the system that has permissions to /upload/files/ folder.
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Analysis
by VulDB Data Team • 10/14/2021
The vulnerability identified as CVE-2021-40887 affects Projectsend version r1295 and represents a critical directory traversal flaw that enables unauthorized access to system files through improper input validation. This vulnerability resides in the handling of the files[] parameter within the application's file management functionality, where insufficient sanitization allows attackers to manipulate file paths and navigate beyond the intended upload directory. The flaw specifically impacts the /upload/files/ folder permissions structure, creating a pathway for malicious actors to access PHP files and other system resources that should remain restricted.
The technical implementation of this vulnerability stems from a lack of proper input validation and sanitization mechanisms within the file handling code. When the application processes the files[] parameter, it fails to properly validate or sanitize user-supplied paths, allowing directory traversal sequences such as ../ to be injected directly into file operations. This weakness creates a direct pathway for attackers to bypass normal file access controls and potentially execute arbitrary code or access sensitive system information. The vulnerability operates at the application layer and can be exploited through HTTP requests that manipulate the file parameter, making it particularly dangerous in web-based environments where user input is frequently processed without adequate security checks.
From an operational impact perspective, this vulnerability poses significant risks to organizations using Projectsend version r1295 as it could allow attackers to access sensitive files, potentially including configuration files, database credentials, or other system resources stored within the upload directory. The ability to traverse directories and access PHP files specifically presents risks of code execution or information disclosure, as PHP files often contain application logic, database connection details, or other sensitive configuration data. The vulnerability's exploitation requires minimal technical expertise and can be automated, making it particularly dangerous in environments where the application is publicly accessible or where users have the ability to upload files.
Security practitioners should consider this vulnerability in the context of CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The ATT&CK framework categorizes this as part of the privilege escalation and persistence techniques where adversaries leverage path traversal vulnerabilities to gain unauthorized access to system resources. Organizations should implement immediate mitigations including input validation, parameter sanitization, and proper access controls to prevent directory traversal attacks. The recommended approach involves implementing strict validation of file paths, using whitelist-based file name validation, and ensuring that all user-supplied input is properly escaped or encoded before processing. Additionally, implementing proper file permissions and restricting write access to upload directories can significantly reduce the impact of such vulnerabilities.
The vulnerability demonstrates the critical importance of input validation in web applications and highlights the need for comprehensive security testing during development cycles. Proper implementation of security controls such as secure file handling practices, input sanitization, and access control mechanisms would prevent this vulnerability from being exploited. Organizations should conduct regular security assessments of their applications to identify similar path traversal vulnerabilities and ensure that all file handling operations implement proper validation and sanitization techniques. The vulnerability also underscores the importance of keeping software components updated and applying security patches promptly to prevent exploitation of known vulnerabilities in widely used applications.