CVE-2020-8438 in ZoneFlex R500
Summary
by MITRE
Ruckus ZoneFlex R500 104.0.0.0.1347 devices allow an authenticated attacker to execute arbitrary OS commands via the hidden /forms/nslookupHandler form, as demonstrated by the nslookuptarget=|cat${IFS} substring.
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Analysis
by VulDB Data Team • 03/27/2024
The vulnerability CVE-2020-8438 affects Ruckus ZoneFlex R500 access points running firmware version 104.0.0.0.1347 and potentially other versions in the same release line. This represents a critical command injection flaw that enables authenticated attackers to execute arbitrary operating system commands on the affected devices. The vulnerability exists within a hidden administrative form located at /forms/nslookupHandler which is not intended for public access but can be reached by authenticated users. The specific attack vector involves manipulating the nslookuptarget parameter through the use of shell metacharacters including the pipe character | and the cat command with IFS (Internal Field Separator) variable to achieve command execution.
This vulnerability falls under the CWE-77 weakness category, specifically representing a command injection flaw where attacker-controlled input is directly passed to the operating system without proper sanitization or validation. The attack demonstrates the use of shell command injection techniques where the | character allows chaining commands and the ${IFS} variable serves to bypass certain input filters by providing an alternative way to separate command arguments. The nslookupHandler form appears to process network lookup requests but fails to properly validate or sanitize user input before executing system commands, creating a path for arbitrary code execution.
The operational impact of this vulnerability is severe as it allows authenticated attackers with access to the device's web interface to gain complete control over the affected Ruckus ZoneFlex R500 devices. This command execution capability can be used to escalate privileges, modify device configurations, extract sensitive information, or even establish persistent backdoors within the network infrastructure. The vulnerability affects enterprise wireless networks where these devices are commonly deployed, potentially allowing attackers to compromise network access points and use them as entry points for broader network infiltration. Given that the attack requires only authentication, the risk is elevated as it can be exploited by insiders or attackers who have obtained valid credentials.
Mitigation strategies for CVE-2020-8438 should include immediate firmware updates from Ruckus to address the command injection vulnerability in the nslookupHandler form. Network administrators should also implement strict access controls to limit who can access the device management interfaces and consider disabling unnecessary administrative functions. The principle of least privilege should be applied to restrict access to only authorized personnel with legitimate business needs. Additionally, network segmentation and monitoring of administrative access attempts can help detect and prevent exploitation attempts. Security professionals should also consider implementing web application firewalls to filter out suspicious command injection patterns and regularly audit device configurations to ensure that hidden administrative interfaces are properly secured or disabled when not required. The vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, specifically the use of shell commands to execute arbitrary code on compromised systems.