CVE-2018-6328 in Backup
Summary
by MITRE
It was discovered that the Unitrends Backup (UB) before 10.1.0 user interface was exposed to an authentication bypass, which then could allow an unauthenticated user to inject arbitrary commands into its /api/hosts parameters using backquotes.
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Analysis
by VulDB Data Team • 12/21/2024
The vulnerability identified as CVE-2018-6328 represents a critical authentication bypass flaw in Unitrends Backup versions prior to 10.1.0 that exposes the system to arbitrary command execution. This issue affects the user interface component of the backup solution and demonstrates a fundamental failure in access control mechanisms that allows unauthorized users to bypass the authentication layer entirely. The vulnerability specifically targets the /api/hosts endpoint where the system fails to properly validate user credentials before processing requests, creating an entry point for malicious actors to exploit.
The technical implementation of this vulnerability stems from improper input validation and sanitization within the API parameter handling mechanism. When an unauthenticated user submits requests to the /api/hosts endpoint, the system accepts parameters that contain backquote characters used for command injection. This occurs because the application fails to properly escape or filter special characters that could be interpreted as shell commands by the underlying operating system. The backquote syntax allows attackers to execute arbitrary commands in the context of the application's privileges, effectively providing a backdoor for malicious activity.
From an operational impact perspective, this vulnerability creates a severe risk landscape for organizations using affected Unitrends Backup versions. The authentication bypass combined with command injection capabilities allows attackers to execute arbitrary code with the privileges of the backup application, potentially leading to complete system compromise. Attackers could leverage this vulnerability to gain access to backup data, modify backup configurations, or even establish persistent access through the compromised backup infrastructure. The implications extend beyond immediate system compromise as backup systems often contain sensitive organizational data and may serve as critical infrastructure components in disaster recovery scenarios.
This vulnerability aligns with CWE-287 which addresses improper authentication issues, and CWE-78 which covers improper neutralization of special elements used in OS commands. The attack vector maps to ATT&CK technique T1059.001 for command and scripting interpreter and T1078 for valid accounts, as the authentication bypass enables exploitation without proper credentials while the command injection allows execution of arbitrary code. Organizations should prioritize immediate patching to version 10.1.0 or later, which addresses the authentication bypass and implements proper input validation for API parameters. Additional mitigations include network segmentation to limit access to the backup interface, implementing web application firewalls to detect and block malicious API requests, and conducting thorough security assessments of backup infrastructure to identify potential lateral movement opportunities. The vulnerability underscores the importance of proper authentication mechanisms and input validation in web applications, particularly those handling sensitive operational data in enterprise environments.