CVE-2017-16673 in Backup Agent
Summary
by MITRE
Datto Backup Agent 1.0.6.0 and earlier does not authenticate incoming connections. This allows an attacker to impersonate a Datto Backup Appliance to "pair" with the agent and issue requests to this agent, if the attacker can reach the agent on TCP port 25566 or 25568, and send unspecified "specific information" by which the agent identifies a network device that is "appearing to be a valid Datto."
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Analysis
by VulDB Data Team • 12/05/2019
The vulnerability identified as CVE-2017-16673 represents a critical authentication flaw in Datto Backup Agent versions 1.0.6.0 and earlier, exposing organizations to significant security risks through improper connection handling. This issue stems from the agent's failure to validate incoming connections, creating an attack vector that allows unauthorized entities to establish fraudulent partnerships with the backup system. The vulnerability specifically affects the agent's communication protocols on TCP ports 25566 and 25568, which are designated for device pairing and management operations. The lack of authentication mechanisms means that any attacker who can establish network connectivity to these ports can potentially impersonate legitimate Datto appliances and gain unauthorized access to the backup agent's functionality.
The technical implementation of this vulnerability allows an attacker to exploit the pairing mechanism by sending specific information that the agent uses to identify network devices. This process relies on the agent's inability to verify the legitimacy of the connecting device, effectively bypassing the normal authentication flow that should validate the identity of the appliance attempting to establish communication. The flaw operates at the network protocol level where the agent accepts pairing requests without proper verification of the source device's credentials or identity. This weakness creates a persistent security gap that remains active as long as the vulnerable agent is running and accessible on the network, making it particularly dangerous for environments where backup agents are exposed to untrusted network segments.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential data compromise and system disruption within backup environments. An attacker who successfully exploits this vulnerability could issue arbitrary commands to the compromised backup agent, potentially leading to data exfiltration, backup corruption, or unauthorized modification of backup configurations. The attack surface is particularly concerning because backup systems often contain sensitive organizational data, making them attractive targets for adversaries seeking to access valuable information. Additionally, the vulnerability could enable attackers to disrupt backup operations, potentially causing data loss or preventing legitimate backup activities from completing successfully. This risk is compounded by the fact that backup agents typically run with elevated privileges and may have access to sensitive system resources, making the compromised agent a potential gateway for further attacks within the network infrastructure.
Organizations affected by this vulnerability should implement immediate mitigations including network segmentation to restrict access to the vulnerable TCP ports 25566 and 25568, ensuring that only trusted devices can communicate with backup agents. Network access control lists should be configured to limit connections to these ports from known legitimate sources only. The implementation of additional network monitoring and intrusion detection systems can help identify suspicious pairing attempts that may indicate exploitation attempts. System administrators should also consider disabling unnecessary backup agent functionality when not actively required and ensure that all systems are updated to versions that properly implement authentication mechanisms. This vulnerability aligns with CWE-287, which addresses improper authentication issues, and represents a clear violation of the principle of least privilege by allowing unrestricted access to backup management functions. From an ATT&CK framework perspective, this vulnerability maps to techniques involving initial access through network service exploitation and privilege escalation through compromised backup systems, highlighting the need for comprehensive network security controls and regular vulnerability assessments to prevent such critical flaws from being exploited in operational environments.