CVE-2019-6551 in Internet FAX ATA
Summary
by MITRE
Pangea Communications Internet FAX ATA all Versions 3.1.8 and prior allow an attacker to bypass user authentication using a specially crafted URL to cause the device to reboot, which may be used to cause a continual denial-of-service condition.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/26/2023
The vulnerability identified as CVE-2019-6551 affects Pangea Communications Internet FAX ATA devices running firmware versions 3.1.8 and earlier, representing a critical authentication bypass flaw that can be exploited to disrupt service availability. This device type serves as a gateway for fax communications over internet protocol networks, making it a potential target for attackers seeking to compromise communication infrastructure. The vulnerability stems from improper handling of specially crafted URLs that can be used to trigger unauthorized device reboots without proper authentication mechanisms. The flaw exists within the device's web interface handling logic where input validation is insufficient to prevent malicious URL parameters from being processed.
The technical implementation of this vulnerability allows an attacker to construct specific URL requests that bypass the normal authentication procedures required to access administrative functions. When such malformed URLs are processed by the device, they trigger a reboot sequence that can be executed repeatedly, leading to sustained service disruption. This authentication bypass occurs at the application layer where the device fails to properly validate incoming requests before executing administrative commands. The issue manifests as a lack of proper access control checks in the web server component, which is classified under CWE-287 - Improper Authentication. The vulnerability can be exploited remotely without requiring any prior authentication credentials, making it particularly dangerous for networked devices.
From an operational perspective, this vulnerability creates a significant risk of denial-of-service conditions that can persist for extended periods if not addressed promptly. The continuous reboot cycles can render the fax communication system completely inoperative, disrupting business operations that depend on fax services. Attackers can maintain persistent disruption by repeatedly sending the malicious URLs, effectively keeping the device in a constant state of rebooting. The impact extends beyond simple service interruption as it can affect critical business communications, potentially causing financial losses and operational delays. This vulnerability aligns with ATT&CK technique T1499.004 - Endpoint Denial of Service, which specifically addresses methods of causing service unavailability through device manipulation.
The security implications of this vulnerability are substantial as it demonstrates a fundamental flaw in the device's security architecture where administrative functions can be triggered without proper authorization. Organizations using these devices face the risk of both intentional disruption and potential exploitation for more advanced attacks that might leverage the service interruption as a cover for other malicious activities. The vulnerability affects the availability aspect of the CIA triad, specifically targeting the device's ability to maintain consistent service delivery. Mitigation strategies should include immediate firmware updates to versions that address the authentication bypass issue, network segmentation to limit access to these devices, and implementation of network monitoring to detect suspicious URL patterns. Additionally, administrators should disable unnecessary web interfaces and implement proper access controls to minimize the attack surface. The vulnerability highlights the importance of proper input validation and authentication mechanisms in embedded network devices, particularly those handling critical communication services.