CVE-2022-4402 in DocSys
Summary
by MITRE • 12/11/2022
A vulnerability classified as critical has been found in RainyGao DocSys 2.02.37. This affects an unknown part of the component ZIP File Decompression Handler. The manipulation leads to path traversal: '../filedir'. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. The associated identifier of this vulnerability is VDB-215271.
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Analysis
by VulDB Data Team • 01/02/2023
This critical vulnerability in RainyGao DocSys 2.02.37 represents a severe path traversal flaw within the ZIP File Decompression Handler component that enables remote attackers to access arbitrary files on the affected system. The vulnerability manifests when the application processes ZIP archives without proper validation of file paths, allowing malicious actors to exploit directory traversal sequences such as '../filedir' to navigate outside the intended directory structure. This weakness falls under CWE-22 Path Traversal and aligns with ATT&CK technique T1059.007 for executing commands through file system access. The remote exploitation capability means attackers can leverage this vulnerability from outside the network perimeter without requiring local access or authentication, making it particularly dangerous for web-facing applications.
The technical implementation of this vulnerability occurs during the decompression process when the ZIP handler fails to sanitize or validate file paths contained within compressed archives. When a ZIP file is processed, the system should verify that extracted file paths remain within the designated extraction directory. However, the current implementation allows attackers to include '../' sequences in file names that, when processed, result in paths that traverse upward in the directory hierarchy. This enables access to sensitive files such as configuration files, database credentials, application source code, or system files that should remain isolated from user-controlled inputs. The vulnerability exists at the input validation layer where the application trusts the file paths contained within ZIP archives without proper sanitization or canonicalization checks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can lead to complete system compromise when combined with other attack vectors. Remote attackers can potentially access sensitive data, modify system files, or even execute arbitrary code if they can place malicious files in writable directories. The public disclosure of the exploit (VDB-215271) increases the risk significantly, as threat actors can immediately leverage this known vulnerability without requiring additional reconnaissance. This type of vulnerability is particularly concerning in document management systems where users frequently upload and download files, as attackers can craft malicious ZIP archives containing path traversal sequences to access system resources. The attack surface is broad since any application that processes user-uploaded ZIP files without proper validation is potentially vulnerable to this class of attack.
Organizations should implement immediate mitigations including input validation for all file paths extracted from ZIP archives, implementing strict directory traversal checks, and ensuring that decompression operations occur within chroot-like environments or restricted directories. The solution requires proper canonicalization of file paths and enforcement of directory boundaries during extraction processes. Security measures should include implementing the principle of least privilege for decompression handlers, logging all file extraction activities, and monitoring for suspicious path sequences. Additionally, organizations should consider deploying web application firewalls that can detect and block path traversal attempts, and regularly update the DocSys application to versions that address this vulnerability. The implementation of proper file name sanitization and validation should be enforced at multiple layers including the application code, network infrastructure, and system-level controls to provide defense in depth against this and similar vulnerabilities.