CVE-2017-9382 in VeraEdge
Summary
by MITRE
An issue was discovered on Vera VeraEdge 1.7.19 and Veralite 1.7.481 devices. The device provides UPnP services that are available on port 3480 and can also be accessed via port 80 using the url "/port_3480". It seems that the UPnP services provide "file" as one of the service actions for a normal user to read a file that is stored under the /etc/cmh-lu folder. It retrieves the value from the "parameters" query string variable and then passes it to an internal function "FileUtils::ReadFileIntoBuffer" which is a library function that does not perform any sanitization on the value submitted and this allows an attacker to use directory traversal characters "../" and read files from other folders within the device.
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Analysis
by VulDB Data Team • 10/05/2023
The vulnerability identified as CVE-2017-9382 affects VeraEdge 1.7.19 and Veralite 1.7.481 devices, representing a critical directory traversal flaw within the Universal Plug and Play (UPnP) implementation. These smart home devices expose UPnP services on port 3480 and additionally provide access via port 80 through the URL path "/port_3480", creating multiple attack vectors for exploitation. The vulnerability stems from the device's UPnP service implementation that allows normal users to perform file reading operations through a specific service action designated for "file" operations. This functionality appears to be intended for legitimate device management purposes but lacks proper input validation mechanisms.
The technical flaw manifests when the UPnP service processes the "parameters" query string variable, which contains user-supplied data that should be treated as potentially malicious. The system passes this unsanitized input directly to the internal library function "FileUtils::ReadFileIntoBuffer" without any form of input sanitization or validation. This design flaw creates a classic path traversal vulnerability where an attacker can manipulate the input to include directory traversal sequences such as "../" to navigate outside the intended directory structure. The device's file system structure allows access to files stored under the /etc/cmh-lu folder, but due to the lack of proper input validation, attackers can traverse beyond this restricted directory and access sensitive files stored in other locations within the device's file system.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with unauthorized access to sensitive information stored on the device. An attacker can potentially read configuration files, authentication credentials, system logs, and other sensitive data that may be stored in directories accessible through the traversal mechanism. This vulnerability directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The implications extend beyond simple information disclosure, as the leaked data could potentially be used for further exploitation, including privilege escalation, credential theft, or establishing persistent access to the device. The vulnerability affects devices that are typically deployed in home and small office environments, where they may control critical home automation functions, making the potential impact even more significant.
The security implications align with ATT&CK technique T1083, which covers directory and file system discovery, as the vulnerability enables unauthorized enumeration and access to the device's file system. Mitigation strategies should focus on implementing proper input validation and sanitization mechanisms to prevent directory traversal attacks. The most effective immediate fix involves sanitizing all user-supplied input parameters before they are processed by internal functions, specifically implementing proper path validation that prevents traversal sequences from being processed. Device vendors should also consider implementing a whitelist approach for file access operations, limiting file access to specific, predefined directories and ensuring that all input undergoes strict validation before being used in file system operations. Additionally, network segmentation and access controls should be implemented to limit exposure of UPnP services to trusted networks only, reducing the attack surface available to potential adversaries. The vulnerability highlights the importance of secure coding practices and input validation in embedded systems, particularly those handling user-supplied data in network services.