CVE-2019-13269 in BR-6208AC V1
Summary
by MITRE
Edimax BR-6208AC V1 devices have Insufficient Compartmentalization between a host network and a guest network that are established by the same device. A DHCP Request is sent to the router with a certain Transaction ID field. Following the DHCP protocol, the router responds with an ACK or NAK message. Studying the NAK case revealed that the router erroneously sends the NAK to both Host and Guest networks with the same Transaction ID as found in the DHCP Request. This allows encoding of data to be sent cross-router into the 32-bit Transaction ID field.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/07/2023
The vulnerability identified as CVE-2019-13269 affects Edimax BR-6208AC V1 wireless routers, specifically targeting the network isolation mechanisms designed to separate host and guest networks. This issue represents a critical failure in network compartmentalization that violates fundamental security principles of network segmentation. The device fails to properly maintain distinct network boundaries between its primary host network and secondary guest network, creating an unintended communication channel that undermines the security posture of the entire network infrastructure.
The technical flaw manifests in the router's handling of DHCP protocol messages, particularly when processing DHCP NAK responses. During normal DHCP operations, routers use transaction IDs to correlate requests with responses, ensuring proper communication between client devices and network infrastructure. However, in this vulnerable implementation, when a DHCP NAK message is generated, the router incorrectly broadcasts the same transaction ID value to both the host network and the guest network simultaneously. This behavior creates a cross-network communication channel that bypasses the intended network isolation mechanisms.
The operational impact of this vulnerability is significant as it enables attackers to exploit the shared transaction ID field to encode and transmit data between network segments that should remain isolated. This cross-communication capability allows for potential information leakage, unauthorized data exfiltration, and could facilitate further attacks across network boundaries. The 32-bit transaction ID field becomes a vector for cross-network data injection, potentially enabling attackers to manipulate network operations or gather sensitive information from different network segments. This vulnerability directly relates to CWE-284, which addresses insufficient compartmentalization in network security contexts, and aligns with ATT&CK technique T1046 for network service scanning and T1566 for credential harvesting through network infiltration.
Mitigation strategies for this vulnerability should focus on implementing proper network segmentation controls and ensuring that DHCP responses maintain appropriate network boundaries. Network administrators should consider updating firmware to versions that address this specific issue, as the vulnerability is fundamentally rooted in the router's firmware implementation. Additionally, implementing network monitoring solutions that can detect anomalous DHCP traffic patterns and transaction ID usage can help identify potential exploitation attempts. The most effective long-term solution involves replacing affected devices with models that properly enforce network compartmentalization or implementing additional network security controls such as VLAN segmentation, firewall rules, and access control lists that can prevent cross-network communication at the network layer. Organizations should also consider deploying network intrusion detection systems that can monitor for unusual DHCP behavior and alert on potential exploitation attempts targeting this specific vulnerability.