CVE-2021-45966 in Cloud Phone System
Summary
by MITRE • 03/18/2022
An issue was discovered in Pascom Cloud Phone System before 7.20.x. In the management REST API, /services/apply in exd.pl allows remote attackers to execute arbitrary code via shell metacharacters.
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Analysis
by VulDB Data Team • 03/20/2022
The vulnerability identified as CVE-2021-45966 represents a critical remote code execution flaw within the Pascom Cloud Phone System version 7.19.x and earlier. This security weakness exists within the management REST API, specifically in the /services/apply endpoint of the exd.pl script which serves as a critical interface for system administration and service management. The vulnerability arises from insufficient input validation and sanitization mechanisms that fail to properly handle shell metacharacters within the API parameters, creating an exploitable path for malicious actors to inject and execute arbitrary commands on the underlying system.
The technical exploitation of this vulnerability occurs through the manipulation of the exd.pl script's handling of input parameters within the REST API endpoint. When a remote attacker submits specially crafted requests to the /services/apply endpoint, the system processes these inputs without adequate sanitization, allowing shell metacharacters such as semicolons, pipes, or command substitution operators to be interpreted and executed by the system shell. This creates a direct pathway for attackers to execute arbitrary code with the privileges of the affected service account, potentially leading to complete system compromise. The vulnerability maps to CWE-78 which specifically addresses "Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')", a well-documented weakness in software systems that fail to properly escape or validate input before incorporating it into system commands.
The operational impact of this vulnerability is severe and multifaceted, as it allows attackers to gain unauthorized access to the system and execute commands that could range from simple reconnaissance to complete system takeover. An attacker could leverage this vulnerability to install backdoors, exfiltrate sensitive data, modify system configurations, or even escalate privileges to gain administrative control over the entire phone system infrastructure. The implications extend beyond the immediate system compromise, as the Pascom Cloud Phone System likely manages critical communication infrastructure within enterprise environments, making this vulnerability particularly dangerous for organizations relying on unified communications and collaboration platforms. This vulnerability could also enable attackers to pivot within the network, using the compromised phone system as a launching point for further attacks against other network segments.
Organizations affected by this vulnerability should implement immediate mitigations including applying the vendor-provided patches and updates released for version 7.20.x and later, which address the input validation issues in the exd.pl script. Network segmentation and access controls should be strengthened to limit exposure of the management REST API endpoints to trusted networks only, implementing proper firewall rules and authentication mechanisms. Additionally, monitoring and logging should be enhanced to detect suspicious API access patterns and command execution attempts. The remediation efforts should align with ATT&CK framework techniques such as T1059.001 for command and scripting interpreter and T1078.004 for valid accounts, as attackers leveraging this vulnerability would likely employ these methods for persistence and lateral movement. Security teams should also conduct comprehensive vulnerability assessments to identify any potential exploitation attempts that may have already occurred within their environments, as this type of vulnerability often results in persistent backdoor installations that can remain undetected for extended periods.