CVE-2019-13263 in DIR-825AC G1
Summary
by MITRE
D-link DIR-825AC G1 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.
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Analysis
by VulDB Data Team • 12/07/2023
The vulnerability identified as CVE-2019-13263 affects D-Link DIR-825AC G1 wireless routers and represents a significant security flaw in network compartmentalization mechanisms. This issue stems from inadequate segregation between host and guest network environments within the same device, creating a pathway for cross-network data injection attacks. The vulnerability manifests through the DHCP protocol implementation where the router fails to properly isolate network communications, allowing malicious actors to exploit the shared transaction ID field across different network segments. The flaw specifically impacts the router's handling of DHCP NAK messages, which are typically used to reject invalid DHCP requests and inform clients of configuration issues.
The technical implementation of this vulnerability follows established DHCP protocol standards while exploiting a critical design oversight in the router's network isolation mechanisms. When a DHCP request is received, the router processes it with a specific transaction ID field that should normally be unique to the requesting network segment. However, in the NAK response scenario, the router incorrectly broadcasts the same transaction ID to both host and guest networks simultaneously. This behavior creates a predictable communication channel that adversaries can manipulate to inject encoded data payloads into the guest network segment. The vulnerability is particularly concerning because it operates at the network protocol level, bypassing traditional application-layer security controls.
From an operational impact perspective, this vulnerability enables attackers to perform cross-network data injection attacks that could compromise guest network users and potentially escalate to host network access. The 32-bit transaction ID field serves as the attack vector, allowing malicious actors to encode information that gets transmitted across network boundaries. This flaw could facilitate various attack scenarios including man-in-the-middle operations, network reconnaissance, and potential privilege escalation within the compromised network environment. The vulnerability affects the fundamental security principle of network segmentation that organizations rely upon to isolate sensitive resources from less trusted network zones.
Security professionals should note this vulnerability aligns with CWE-284 (Improper Access Control) and CWE-310 (Cryptographic Issues) categories, as it represents improper network compartmentalization and potential cryptographic weakness in transaction handling. The attack surface extends beyond simple data injection to include potential information disclosure and network disruption capabilities. Organizations using D-Link DIR-825AC G1 devices should implement immediate mitigations including firmware updates from D-Link, network segmentation through additional firewall rules, and monitoring for anomalous DHCP traffic patterns. The vulnerability also maps to ATT&CK technique T1046 (Network Service Scanning) and T1566 (Phishing) as attackers could use this flaw to establish persistent access or deliver malicious payloads to guest network users. Network administrators should consider implementing intrusion detection systems to monitor for suspicious transaction ID patterns and ensure proper network segmentation controls are in place to prevent lateral movement between network segments.