A critical remote command injection vulnerability, identified as CVE-2020-37027, exists within Sickbeard alpha. This flaw allows an unauthenticated attacker to remotely execute arbitrary commands on the server by injecting malicious code into the "extra scripts" configuration, leading to a complete system compromise.

This vulnerability is a command injection flaw within the "extra scripts" feature of Sickbeard alpha. The application fails to properly sanitize user-supplied input to this configuration field. An unauthenticated remote attacker can submit a request to the application to set a malicious script or command (e.g., ;/bin/bash -c '...'). When the application triggers the execution of these extra scripts (for example, after a download completes), the injected command is executed on the underlying operating system with the privileges of the Sickbeard service account.

This vulnerability is rated as critical severity with a CVSS score of 9.8. Successful exploitation grants an attacker complete control over the affected server, resulting in a full system compromise. Potential consequences include theft or destruction of sensitive data, deployment of ransomware, installation of persistent backdoors, and using the compromised server as a pivot point to attack other systems within the network. The lack of an authentication requirement significantly increases the risk, as any attacker with network access to the Sickbeard instance can exploit this flaw.

Immediate Action: Update Sickbeard alpha to the latest version that addresses this vulnerability. After patching, it is crucial to monitor for any signs of post-exploitation activity. Review application and system access logs for any unusual commands or connections originating from the Sickbeard server that may indicate a previous compromise.

Proactive Monitoring: Monitor application logs for unusual entries or modifications to the "extra scripts" configuration. On the host system, monitor for unexpected child processes being spawned by the Sickbeard process (e.g., sh, bash, curl, wget). Network monitoring should be in place to detect anomalous outbound traffic from the Sickbeard server, which could indicate data exfiltration or connection to a command-and-control server.

Compensating Controls: If immediate patching is not feasible, implement the following controls:

• Restrict network access to the Sickbeard web interface using a firewall, allowing connections only from trusted IP addresses.
• Place the service behind a reverse proxy that requires strong authentication.
• Run the Sickbeard application with a dedicated, low-privilege user account to limit the impact of a potential compromise.
• Utilize a Web Application Firewall (WAF) with rules designed to detect and block command injection attempts.

Public Exploit Available: true

Given the critical severity (CVSS 9.8) and the unauthenticated remote code execution nature of this vulnerability, immediate action is required. Organizations must prioritize applying the vendor-supplied patches to all affected Sickbeard alpha installations. Due to the high likelihood of automated scanning and exploitation, any internet-exposed instances should be considered at extreme risk and either patched or taken offline immediately until they can be secured.