CVE-2019-9106 in Impianti Speciali TEBE Small
Summary
by MITRE
The WebApp v04.68 in the supervisor on SAET Impianti Speciali TEBE Small 05.01 build 1137 devices allows remote attackers to execute or include local .php files, as demonstrated by menu=php://filter/convert.base64-encode/resource=index.php to read index.php.
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Analysis
by VulDB Data Team • 09/25/2023
The vulnerability identified as CVE-2019-9106 affects the WebApp component of SAET Impianti Speciali TEBE Small 05.01 devices running supervisor version 04.68 build 1137. This represents a critical security flaw that enables remote attackers to perform local file inclusion attacks through improper input validation mechanisms. The vulnerability specifically manifests when the application processes user-supplied input without adequate sanitization, allowing malicious actors to manipulate the application's file handling behavior. The attack vector demonstrated in the exploit shows how an attacker can leverage the menu parameter to traverse file systems and access sensitive PHP files through base64 encoding, effectively bypassing normal access controls and exposing server-side code.
The technical flaw stems from insufficient validation and sanitization of user input parameters within the web application's request handling logic. This vulnerability directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal attacks. The application fails to properly validate the menu parameter, allowing arbitrary file path manipulation that can lead to unauthorized access to local files including PHP source code, configuration files, and potentially sensitive system resources. The use of php://filter protocol in the exploit demonstrates the attacker's ability to manipulate PHP's stream wrapper functionality to encode and retrieve file contents without direct execution, making the attack more stealthy and effective.
The operational impact of this vulnerability is severe as it provides attackers with unauthorized access to sensitive application files and potentially system resources. Remote code execution capabilities through local file inclusion can enable attackers to gain full control over the affected device, allowing them to execute arbitrary commands, escalate privileges, and establish persistent access. This vulnerability particularly affects industrial control systems and embedded devices where security is often overlooked due to operational requirements and limited patching capabilities. The exposure of index.php and other PHP files through base64 encoding indicates that attackers could potentially extract application logic, database credentials, and other sensitive information that could be used for further attacks within the network infrastructure.
Mitigation strategies for CVE-2019-9106 should include immediate patching of the affected software to address the input validation flaws and implement proper parameter sanitization. Network segmentation and firewall rules should be configured to restrict access to the affected device to only authorized personnel and systems. Implementing web application firewalls can help detect and block malicious requests attempting to exploit this vulnerability. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other components of the industrial control system. Additionally, the principle of least privilege should be enforced by limiting the web application's file access permissions and ensuring that sensitive files are not directly accessible through the web interface. Organizations should also implement proper monitoring and logging mechanisms to detect suspicious file access patterns and potential exploitation attempts. The vulnerability highlights the importance of secure coding practices and input validation in embedded systems, particularly in industrial environments where device security can directly impact operational technology infrastructure.