CVE-2018-17564 in GXP16xx VoIP
Summary
by MITRE
A Malformed Input String to /cgi-bin/delete_CA on Grandstream GXP16xx VoIP 1.0.4.128 phones allows attackers to delete configuration parameters and gain admin access to the device.
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Analysis
by VulDB Data Team • 08/21/2023
The vulnerability identified as CVE-2018-17564 represents a critical security flaw in Grandstream GXP16xx VoIP phones running firmware version 1.0.4.128. This issue resides within the web-based administration interface of these devices, specifically in the /cgi-bin/delete_CA script which handles certificate authority deletion operations. The vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly process malformed string inputs submitted through the web interface. Attackers can exploit this weakness by crafting specially crafted malicious inputs that bypass normal validation checks and manipulate the device's configuration parameters.
The technical nature of this vulnerability aligns with CWE-20, which describes improper input validation, and CWE-79, which covers cross-site scripting vulnerabilities that can be exploited to manipulate device behavior. The flaw operates through a classic buffer overflow or injection attack pattern where malformed input strings are passed directly to the delete_CA script without adequate sanitization. When the device processes these malformed inputs, it executes unintended code paths that allow deletion of critical configuration parameters. This manipulation creates a privilege escalation scenario where unauthenticated attackers can gain administrative access to the VoIP device, effectively compromising the entire communication infrastructure it manages.
The operational impact of this vulnerability extends far beyond simple configuration parameter deletion. Once attackers achieve administrative access, they can modify all device settings including SIP account credentials, network configurations, and potentially establish backdoor access points. The attack surface is particularly concerning for enterprise environments where these devices often serve as gateways for internal communication systems. The vulnerability enables attackers to perform man-in-the-middle attacks on VoIP communications, intercept sensitive business conversations, and potentially escalate their access to other network segments through the compromised device. The lack of authentication requirements for this particular attack vector means that even unauthenticated users can exploit the flaw, making it particularly dangerous for publicly accessible VoIP systems.
Security professionals should implement multiple layers of defense to mitigate this vulnerability. Immediate remediation requires updating firmware to versions that address the input validation flaws, with the specific patch details available through Grandstream security advisories. Network segmentation should be enforced to isolate VoIP devices from critical business systems, and access controls should be implemented to restrict administrative access to authorized personnel only. The implementation of web application firewalls and intrusion detection systems can help monitor for suspicious patterns in web requests that might indicate exploitation attempts. Additionally, regular security audits of VoIP infrastructure should include vulnerability scanning for similar input validation flaws, and device configurations should be reviewed to ensure that unnecessary administrative services are disabled. The vulnerability demonstrates the importance of applying the principle of least privilege and maintaining current security patches as outlined in NIST cybersecurity frameworks and MITRE ATT&CK framework's privilege escalation techniques. Organizations should also consider implementing network monitoring solutions that can detect anomalous behavior patterns consistent with exploitation of similar vulnerabilities in VoIP infrastructure.