CVE-2017-13707 in Backup Manager
Summary
by MITRE
Privilege escalation in Replibit Backup Manager earlier than version 2017.08.04 allows attackers to gain root privileges via sudo command execution. The vi program can be accessed through sudo, in order to navigate the filesystem and modify a critical file such as /etc/passwd.
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Analysis
by VulDB Data Team • 11/10/2019
The vulnerability identified as CVE-2017-13707 represents a critical privilege escalation flaw within the Replibit Backup Manager software suite, specifically affecting versions prior to 2017.08.04. This vulnerability exploits a fundamental weakness in the software's handling of privileged operations, creating a pathway for malicious actors to elevate their privileges from standard user level to root access. The flaw resides in the software's integration with the sudo command execution framework, which is designed to allow authorized users to execute commands with elevated privileges. However, this particular implementation fails to properly validate or restrict the commands that can be executed through the sudo interface, creating an exploitable condition that directly undermines the principle of least privilege that forms the cornerstone of secure system design.
The technical exploitation of this vulnerability leverages the vi text editor, which is commonly accessible through sudo privileges in many Unix-like systems. Attackers can utilize this access to navigate the filesystem and directly modify critical system files, most notably the /etc/passwd file, which contains user account information and is essential for system authentication. The vi editor's capabilities extend beyond simple text editing, as it can be used to execute shell commands and manipulate system files in ways that bypass normal access controls. This particular exploit aligns with CWE-276, which addresses improper privileges, and demonstrates how insufficient access control mechanisms can lead to severe security breaches. The vulnerability essentially creates a backdoor through which an attacker can modify the system's user database to add new administrative accounts or modify existing ones, effectively compromising the entire system's integrity and confidentiality.
The operational impact of this privilege escalation vulnerability extends far beyond the immediate compromise of individual systems. When an attacker successfully exploits this vulnerability, they gain complete control over the affected system, enabling them to establish persistent access, exfiltrate sensitive data, and potentially use the compromised system as a launching point for further attacks within a network. The vulnerability's presence in backup management software is particularly concerning because these tools often have elevated privileges to access and modify critical system files, making them attractive targets for attackers seeking to maintain long-term access. The exploit requires minimal sophistication to execute, as it relies on standard Unix utilities and the inherent trust placed in certain system commands, making it a preferred target for both skilled and less experienced attackers. This vulnerability directly relates to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and demonstrates how legitimate system tools can be misused to achieve unauthorized access.
Mitigation strategies for CVE-2017-13707 should focus on immediate remediation through software updates to version 2017.08.04 or later, which would address the underlying privilege escalation mechanism. Organizations should also implement strict sudo configuration policies that limit the commands executable through sudo and employ principle of least privilege when granting elevated access rights. The use of privilege separation techniques and regular security audits of sudo configurations can help identify and prevent similar vulnerabilities. Additionally, monitoring for unauthorized access attempts and suspicious sudo usage patterns should be implemented as part of comprehensive security operations. System administrators should consider implementing additional security controls such as mandatory access controls and privilege management systems that can further restrict the potential impact of such vulnerabilities. The remediation process should include comprehensive testing to ensure that updates do not introduce compatibility issues with existing backup operations while maintaining the security posture of the system.