CVE-2017-9386 in VeraEdge
Summary
by MITRE
An issue was discovered on Vera VeraEdge 1.7.19 and Veralite 1.7.481 devices. The device provides a script file called "get_file.sh" which allows a user to retrieve any file stored in the "cmh-ext" folder on the device. However, the "filename" parameter is not validated correctly and this allows an attacker to directory traverse outside the /cmh-ext folder and read any file on the device. It is necessary to create the folder "cmh-ext" on the device which can be executed by an attacker first in an unauthenticated fashion and then execute a directory traversal attack.
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Analysis
by VulDB Data Team • 10/05/2023
The vulnerability identified as CVE-2017-9386 affects VeraEdge 1.7.19 and Veralite 1.7.481 devices, representing a critical directory traversal flaw that exposes sensitive system information. This issue stems from improper input validation within the "get_file.sh" script, which is designed to allow file retrieval from the "cmh-ext" directory. The flaw lies in the script's failure to properly sanitize the "filename" parameter, creating a path traversal condition that enables attackers to escape the intended directory boundaries.
The technical implementation of this vulnerability follows a specific attack pattern that begins with the creation of the "cmh-ext" folder through unauthenticated means, followed by exploitation of the directory traversal mechanism. This sequence allows attackers to navigate outside the designated "/cmh-ext" folder and access arbitrary files on the device filesystem. The 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 attack vector requires minimal privileges and can be executed without authentication, making it particularly dangerous for networked devices.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with access to potentially sensitive system files that may contain configuration data, user credentials, or other confidential information. The ability to traverse directories and read arbitrary files creates a foundation for further exploitation, including potential privilege escalation or system compromise. This vulnerability aligns with ATT&CK technique T1083, which covers file and directory discovery, and T1566, which encompasses credential harvesting through various attack vectors.
Security implications of this vulnerability are significant for home and small office networks that rely on Vera devices for smart home automation. The unauthenticated nature of the initial folder creation phase means that any network-connected attacker can potentially exploit this vulnerability without requiring prior access credentials. The attack chain demonstrates the importance of input validation and proper access controls in embedded systems, particularly those with web interfaces that provide file access capabilities. Organizations should implement immediate mitigations including firmware updates, network segmentation, and monitoring for unauthorized directory creation attempts. The vulnerability also highlights the need for secure coding practices that prevent path traversal attacks through proper parameter validation and access control mechanisms.