CVE-2018-6926 in MISP
Summary
by MITRE
In app/Controller/ServersController.php in MISP 2.4.87, a server setting permitted the override of a path variable on certain Red Hed Enterprise Linux and CentOS systems (where rh_shell_fix was enabled), and consequently allowed site admins to inject arbitrary OS commands. The impact is limited by the setting being only accessible to the site administrator.
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Analysis
by VulDB Data Team • 02/06/2023
The vulnerability identified as CVE-2018-6926 resides within the MISP (Malware Information Sharing Platform) software version 2.4.87, specifically in the ServersController.php file located at app/Controller/ServersController.php. This flaw represents a critical command injection vulnerability that exploits a path variable override mechanism on specific Linux distributions including Red Hat Enterprise Linux and CentOS systems where the rh_shell_fix configuration is enabled. The vulnerability stems from inadequate input validation and sanitization within the server configuration handling logic, creating a pathway for malicious command execution.
The technical implementation of this vulnerability involves the manipulation of a path variable that, when overridden through specific server settings, enables arbitrary code execution at the operating system level. This occurs because the application fails to properly validate or sanitize user-supplied input that influences path resolution and command execution flows. The vulnerability is particularly dangerous because it leverages legitimate system configuration mechanisms to bypass normal security controls, making it difficult to detect through standard monitoring approaches. The flaw operates at the intersection of improper input validation and privilege escalation, as the affected configuration settings are only accessible to site administrators, though this limitation does not prevent the exploitation from occurring within the privileged context.
The operational impact of this vulnerability is significant for organizations relying on MISP for threat intelligence sharing and incident response activities. An attacker with administrative access to the MISP instance can execute arbitrary operating system commands, potentially leading to full system compromise, data exfiltration, or disruption of threat sharing operations. The vulnerability undermines the integrity of the threat intelligence platform, as malicious actors could manipulate the system to hide their activities or compromise other systems within the network. This risk is compounded by the fact that MISP instances often contain sensitive threat intelligence data that could be valuable to adversaries. The vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and relates to ATT&CK technique T1059.001 for command and scripting interpreter.
Mitigation strategies for this vulnerability require immediate action including applying the official patch released by the MISP project, which addresses the input validation issues in the ServersController.php file. Organizations should also implement strict access controls and privilege separation, ensuring that administrative access to MISP instances is limited to authorized personnel only. Network segmentation and monitoring of command execution activities can help detect potential exploitation attempts. Additionally, implementing proper input sanitization mechanisms and regular security assessments of web applications can prevent similar vulnerabilities from emerging in the future. The vulnerability demonstrates the critical importance of validating all user inputs and properly handling system-level operations within web applications, particularly those involved in security operations and threat intelligence sharing.