CVE-2017-7240 in Professional PG 8528 PST10
Summary
by MITRE
An issue was discovered on Miele Professional PG 8528 PST10 devices. The corresponding embedded webserver "PST10 WebServer" typically listens to port 80 and is prone to a directory traversal attack; therefore, an unauthenticated attacker may be able to exploit this issue to access sensitive information to aide in subsequent attacks. A Proof of Concept is GET /../../../../../../../../../../../../etc/shadow HTTP/1.1.
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Analysis
by VulDB Data Team • 08/04/2024
The vulnerability identified as CVE-2017-7240 affects Miele Professional PG 8528 PST10 devices, which are industrial cleaning equipment units that incorporate embedded web servers for remote management and monitoring capabilities. These devices are commonly deployed in commercial and industrial environments where they require network connectivity for configuration, status reporting, and maintenance purposes. The embedded web server component known as "PST10 WebServer" operates on port 80, making it accessible to network clients without requiring authentication credentials. This exposes the device to various network-based attacks that can exploit the underlying web server implementation's failure to properly validate and sanitize user input.
The technical flaw manifests as a directory traversal vulnerability within the web server's file handling mechanism, which allows an attacker to manipulate HTTP requests to access files outside of the intended web root directory. The specific attack vector demonstrated through the proof of concept GET request reveals how an unauthenticated attacker can construct malicious URLs to navigate through directory structures and retrieve sensitive system files. The vulnerability stems from improper input validation where user-supplied paths are directly processed without adequate sanitization or canonicalization checks, enabling attackers to use sequences like "../" to move up directory levels and access restricted files. This represents a classic implementation of CWE-22, which defines improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with access to critical system files that can aid in subsequent exploitation attempts. The ability to retrieve files such as /etc/shadow demonstrates the severity of the exposure, as this file typically contains hashed passwords for system accounts that can be targeted through offline password cracking attacks. Attackers can leverage this initial access to gather intelligence about the device's configuration, user accounts, and potentially discover additional vulnerabilities within the system. The unauthenticated nature of the attack means that any network-connected device with this vulnerability can be exploited without requiring prior access credentials, making it particularly dangerous in environments where industrial equipment is connected to corporate networks.
Mitigation strategies for CVE-2017-7240 should prioritize immediate network segmentation and access controls to limit exposure of these devices to untrusted networks. Organizations should implement network access control lists that restrict access to port 80 on these devices to only authorized management systems and personnel. The most effective long-term solution involves firmware updates from Miele that properly implement input validation and canonicalize file paths before processing user requests. Security professionals should also consider implementing network monitoring to detect suspicious directory traversal attempts and establish baseline network behavior for these industrial devices. The vulnerability aligns with ATT&CK technique T1083, which covers directory and file system discovery, and represents a common entry point for attackers seeking to establish persistent access to industrial control systems. Organizations should also conduct comprehensive inventory audits to identify all similar devices within their networks that may be vulnerable to similar directory traversal attacks, as this class of vulnerability is prevalent in embedded systems and industrial equipment that often lack proper input validation mechanisms.