Apache Kylin REST API Remote Code Execution (RCE) and OS Command Injection Vulnerability Analysis (CVE-2020-1956)

1. Vulnerability Overview & Root Cause

This vulnerability (CVE-2020-1956) is a critical OS command injection flaw residing in the REST API endpoints of Apache Kylin. The root cause lies in the unsafe concatenation of user-supplied input strings directly into operating system command executions within certain system configuration and migration APIs. Because the input is not properly sanitized or validated against a strict allowlist, attackers can inject shell metacharacters to execute arbitrary system commands under the privileges of the Kylin process.

2. Exploitation Mechanics & Attack Scenario

To exploit this vulnerability, an attacker must first authenticate to the Apache Kylin web console or API (often leveraging default credentials like ADMIN/KYLIN if left unchanged). Once authenticated, the attacker sends a crafted HTTP POST or PUT request to vulnerable REST endpoints, such as those managing Cube or Project configurations. By injecting shell control operators (e.g., &&, |, ;) into parameters like kylin.engine.spark-conf or migration script paths, the attacker forces the underlying operating system to execute arbitrary payloads, such as downloading and executing a malicious shell script.

3. Infrastructure & Business Impact

With a CVSS score of 8.8 (High) and its inclusion in the CISA KEV (Known Exploited Vulnerabilities) catalog, this vulnerability poses a severe threat and is actively targeted in the wild. Successful exploitation grants the attacker shell access to the server hosting Apache Kylin. This can serve as an entry point for lateral movement into critical big data clusters (Hadoop, Spark), leading to massive data exfiltration, ransomware deployment, or unauthorized resource utilization such as cryptomining.