CVE-2018-16221 in Ultra-elegant IP Phone SIP-T41P
Summary
by MITRE
The diagnostics web interface in the Yeahlink Ultra-elegant IP Phone SIP-T41P (firmware 66.83.0.35) does not validate (escape) the path information (path traversal), which allows an authenticated remote attacker to get access to privileged information (e.g., /etc/passwd) via path traversal (relative path information in the file parameter of the corresponding POST request).
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Analysis
by VulDB Data Team • 09/25/2023
The CVE-2018-16221 vulnerability affects the Yeahlink Ultra-elegant IP Phone SIP-T41P device running firmware version 66.83.0.35 and represents a critical path traversal flaw within the device's diagnostics web interface. This vulnerability stems from inadequate input validation and sanitization of path information, specifically within the file parameter of POST requests directed to the diagnostics endpoint. The flaw allows authenticated remote attackers to exploit the system's failure to properly validate user-supplied path data, creating a direct pathway to access sensitive system files and privileged information that should remain restricted to authorized personnel only.
The technical implementation of this vulnerability manifests through the device's insufficient escaping and validation of file path parameters in the web interface. When an attacker submits a malicious POST request containing specially crafted path traversal sequences in the file parameter, the system fails to sanitize or validate the input before processing the request. This lack of proper input validation creates an environment where relative path traversal techniques can be successfully employed to navigate the file system beyond the intended boundaries. The vulnerability specifically targets the diagnostics web interface, which typically provides system administrators with access to various diagnostic tools and system information, making it a prime target for information disclosure attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with access to critical system files that could contain sensitive data such as password hashes, system configurations, and other privileged information. The fact that the attack requires authentication but can be executed remotely means that an attacker who has gained valid credentials for the device can leverage this flaw to escalate their access and gather intelligence about the device's configuration and underlying system. This information could then be used for further exploitation attempts or to facilitate broader attacks within the network infrastructure where the device resides. The vulnerability essentially undermines the device's security boundaries and creates unauthorized access to system-level information that should remain protected.
The vulnerability aligns with CWE-22 Path Traversal and follows patterns consistent with ATT&CK technique T1083 File and Directory Discovery, where adversaries seek to enumerate and access system files and directories. Organizations should implement immediate mitigations including firmware updates from the vendor, network segmentation to limit access to the device, and implementation of web application firewalls to detect and block malicious path traversal attempts. The device should be configured with minimal necessary privileges and access controls should be strictly enforced to prevent unauthorized access to sensitive system information. Additionally, regular security assessments and input validation testing should be conducted to identify similar vulnerabilities in other networked devices within the infrastructure.