CVE-2018-19793 in jiacrontab
Summary
by MITRE
jiacrontab 1.4.5 allows remote attackers to execute arbitrary commands via the crontab/task/edit?addr=localhost%3a20001 command and args parameters, as demonstrated by command=cat&args=/etc/passwd in the POST data.
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Analysis
by VulDB Data Team • 06/12/2023
The vulnerability identified as CVE-2018-19793 affects jiacrontab version 1.4.5, a web-based cron job management tool that provides a graphical interface for configuring and managing cron tasks. This particular flaw represents a critical remote command execution vulnerability that allows attackers to execute arbitrary system commands on the affected server. The vulnerability exists within the task editing functionality of the application, specifically in how it processes user-supplied parameters when modifying cron jobs through the web interface.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the crontab/task/edit endpoint. When attackers submit malicious payloads through the addr parameter containing localhost:20001 and subsequently provide command and args parameters in the POST data, the application fails to properly validate or sanitize these inputs before executing them. The demonstrated attack vector uses command=cat&args=/etc/passwd which shows how an attacker can leverage this vulnerability to read sensitive system files. This represents a classic command injection vulnerability where user-controllable input directly influences system command execution without proper sanitization or escaping mechanisms.
The operational impact of this vulnerability is severe as it provides remote attackers with complete control over the affected system. An attacker can execute any command available to the user account running the jiacrontab service, potentially leading to full system compromise, data exfiltration, or privilege escalation. The vulnerability affects systems where jiacrontab is deployed with default configurations that allow remote access to the web interface, making it particularly dangerous in environments where administrative interfaces are exposed to untrusted networks. This vulnerability directly maps to CWE-77 and CWE-94 in the Common Weakness Enumeration catalog, specifically representing command injection flaws that allow arbitrary code execution.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation. The attack chain typically begins with reconnaissance to identify exposed jiacrontab interfaces followed by exploitation of this command injection vulnerability to gain initial access. Security professionals should note that this vulnerability affects not only the specific version mentioned but potentially other versions that share similar input handling patterns. Organizations should immediately implement network segmentation to restrict access to jiacrontab interfaces, deploy web application firewalls to detect and block malicious payloads, and apply the vendor-provided patch or upgrade to a secure version. Additionally, implementing proper input validation, output encoding, and principle of least privilege for the jiacrontab service account can significantly reduce the risk of exploitation. The vulnerability demonstrates the critical importance of validating all user inputs and implementing proper security controls in web-based administrative interfaces to prevent unauthorized command execution.