CVE-2022-35520 in WN572HP3
Summary
by MITRE • 08/11/2022
WAVLINK WN572HP3, WN533A8, WN530H4, WN535G3, WN531P3 api.cgi has no filtering on parameter ufconf, and this is a hidden parameter which doesn't appear in POST body, but exist in cgi binary. This leads to command injection in page /ledonoff.shtml.
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Analysis
by VulDB Data Team • 09/04/2022
The vulnerability identified as CVE-2022-35520 affects several WAVLINK wireless router models including WN572HP3, WN533A8, WN530H4, WN535G3, and WN531P3. This represents a critical command injection flaw that exploits improper input validation in the web interface configuration handler. The vulnerability specifically targets the api.cgi script which processes requests to the /ledonoff.shtml page, creating a dangerous attack surface where malicious actors can execute arbitrary commands on the affected devices.
The technical flaw stems from the absence of proper parameter filtering for the ufconf parameter within the api.cgi script. This parameter is classified as a hidden parameter that does not appear in the standard POST request body but is embedded within the CGI binary itself. The lack of input sanitization means that user-supplied data passed through this parameter is directly incorporated into system commands without adequate validation or escaping mechanisms. This design flaw allows attackers to inject malicious commands that get executed with the privileges of the web server process, typically running with elevated system permissions.
The operational impact of this vulnerability is severe as it provides attackers with complete command execution capabilities on the affected routers. An attacker could potentially gain full control over the device, modify network configurations, redirect traffic, or establish persistent access points. The hidden nature of the ufconf parameter makes this vulnerability particularly dangerous as it is not immediately obvious to security scanning tools or network administrators. The vulnerability affects the /ledonoff.shtml page which is likely used for controlling LED indicators or other device status features, making the attack vector more subtle and harder to detect during routine security assessments.
This vulnerability aligns with CWE-77 and CWE-94 categories, representing command injection flaws that permit arbitrary code execution through improper input handling. From an ATT&CK framework perspective, this maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) techniques. The attack chain typically involves crafting malicious payloads that exploit the missing input validation to inject system commands that can manipulate the device's functionality. Organizations should implement immediate mitigations including firmware updates from WAVLINK, network segmentation to limit access to affected devices, and monitoring for unusual traffic patterns or command execution attempts on the affected router models.