CVE-2019-16640 in EG-2000
Summary
by MITRE • 07/16/2024
An issue was found in upload.php on the Ruijie EG-2000 series gateway. A parameter passed to the class UploadFile is mishandled (%00 and /var/./html are not checked), which can allow an attacker to upload any file to the gateway. This affects EG-2000SE EG_RGOS 11.9 B11P1.
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Analysis
by VulDB Data Team • 07/09/2025
The vulnerability identified as CVE-2019-16640 resides within the upload.php component of Ruijie EG-2000 series network gateways, specifically impacting the EG-2000SE model running EG_RGOS 11.9 B11P1 firmware version. This represents a critical security flaw that stems from improper input validation and file handling mechanisms within the gateway's web interface. The vulnerability manifests when the system processes file upload requests through the UploadFile class, where certain parameters fail to undergo adequate sanitization checks. The absence of proper validation for null byte sequences and directory traversal patterns creates an exploitable condition that allows malicious actors to bypass intended security restrictions.
The technical exploitation of this vulnerability occurs through manipulation of file upload parameters that contain null byte characters and directory traversal sequences such as %00 and /var/./html. These sequences are not properly filtered or validated by the system, enabling attackers to craft malicious upload requests that can place arbitrary files at predetermined locations within the gateway's filesystem. The lack of comprehensive input validation means that attackers can effectively bypass the intended file type restrictions and upload potentially harmful payloads including web shells, malware, or other malicious executables. This vulnerability directly maps to CWE-73, which describes improper neutralization of special elements used in file names, and CWE-22, which addresses improper limitation of a pathname to a restricted directory. The flaw essentially creates a path traversal condition that allows for arbitrary file placement, making it particularly dangerous in network gateway environments where such devices serve as critical infrastructure points.
The operational impact of this vulnerability extends beyond simple unauthorized file uploads, as it provides attackers with potential persistence mechanisms and privilege escalation capabilities within the affected network gateway. Once an attacker successfully uploads a malicious file, they can potentially execute code on the device, leading to complete compromise of the network gateway's functionality. This compromise can result in man-in-the-middle attacks, traffic interception, network disruption, and unauthorized access to internal network resources. The vulnerability affects the integrity and availability of the network infrastructure, as attackers can manipulate the gateway's behavior to redirect traffic, monitor communications, or disable security functions. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter, specifically focusing on the use of PHP web shells, and T1078 for valid accounts, as successful exploitation may enable attackers to maintain persistent access through uploaded malicious files.
Mitigation strategies for this vulnerability should include immediate firmware updates from Ruijie to address the specific input validation flaws in the upload.php component. Network administrators should implement network segmentation and access controls to limit exposure of gateway devices to untrusted networks. The implementation of web application firewalls and content filtering mechanisms can help detect and block malicious upload attempts. Additionally, regular security audits should verify that file upload functionality properly validates all input parameters and implements strict file type checking. System administrators should also consider disabling unnecessary file upload features and implementing proper file access controls to minimize the impact of potential exploitation. The vulnerability underscores the importance of proper input validation and the principle of least privilege in network security implementations, particularly for critical infrastructure devices that serve as gateways between internal and external networks.