CVE-2020-8813 in Cacti
Summary
by MITRE
graph_realtime.php in Cacti 1.2.8 allows remote attackers to execute arbitrary OS commands via shell metacharacters in a cookie, if a guest user has the graph real-time privilege.
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Analysis
by VulDB Data Team • 11/16/2024
The vulnerability identified as CVE-2020-8813 affects Cacti version 1.2.8 and represents a critical command injection flaw in the graph_realtime.php script. This vulnerability arises from insufficient input validation and sanitization of user-provided data within the cookie parameter, creating an avenue for remote code execution. The flaw specifically targets the real-time graph functionality that is accessible to guest users who possess the appropriate privileges, making it particularly concerning for environments where guest access is permitted. The vulnerability is classified under CWE-77 as a command injection weakness, which directly enables attackers to execute arbitrary operating system commands on the affected system.
The technical exploitation of this vulnerability occurs through the manipulation of cookie values that are processed by the graph_realtime.php script without proper sanitization. When a guest user with real-time graph privileges accesses the affected functionality, the system processes cookie data containing shell metacharacters such as semicolons, ampersands, or backticks that are then passed to system commands without adequate filtering. This allows an attacker to inject malicious commands that execute with the privileges of the web application user, typically running as a system-level account. The vulnerability demonstrates a classic lack of input validation and output encoding that violates fundamental security principles outlined in the OWASP Top Ten and the SANS Top 25.
The operational impact of CVE-2020-8813 extends beyond simple remote code execution to encompass potential system compromise and data exfiltration capabilities. An attacker who successfully exploits this vulnerability can gain full control over the affected Cacti server, potentially leading to privilege escalation, lateral movement within the network, and access to sensitive monitoring data. The real-time graph functionality is often used to display network performance metrics and system information, making the compromised system a valuable target for attackers seeking to gather intelligence about network topology, device configurations, or other operational data. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1078.004 for valid accounts, as it leverages legitimate user privileges to execute malicious commands.
Mitigation strategies for CVE-2020-8813 should focus on immediate patching of the affected Cacti version, as the vendor has released updates addressing this specific vulnerability. Organizations should also implement network segmentation to limit access to the affected functionality, particularly for guest users who do not require real-time graph privileges. Input validation should be strengthened throughout the application to sanitize all cookie values and prevent shell metacharacters from being processed. The principle of least privilege should be enforced by restricting guest user access to only necessary functionality, and additional monitoring should be implemented to detect unusual command execution patterns. Security controls should include web application firewalls that can detect and block suspicious cookie content, as well as regular security assessments to identify similar input validation weaknesses in other components of the monitoring infrastructure. Organizations should also consider implementing multi-factor authentication and privileged access management solutions to reduce the attack surface and limit the potential impact of successful exploitation attempts.