CVE-2016-6563 in DIR-823
Summary
by MITRE
Processing malformed SOAP messages when performing the HNAP Login action causes a buffer overflow in the stack in some D-Link DIR routers. The vulnerable XML fields within the SOAP body are: Action, Username, LoginPassword, and Captcha. The following products are affected: DIR-823, DIR-822, DIR-818L(W), DIR-895L, DIR-890L, DIR-885L, DIR-880L, DIR-868L, and DIR-850L.
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Analysis
by VulDB Data Team • 12/27/2024
The vulnerability identified as CVE-2016-6563 represents a critical buffer overflow condition affecting multiple D-Link DIR series routers, specifically targeting the HNAP (Home Network Administration Protocol) login functionality. This vulnerability stems from inadequate input validation within the SOAP message processing mechanism, where the router fails to properly sanitize XML fields during authentication requests. The affected devices include several models within the DIR-823, DIR-822, DIR-818L(W), DIR-895L, DIR-890L, DIR-885L, DIR-880L, DIR-868L, and DIR-850L families, all of which share the same vulnerable code path in their firmware implementations.
The technical flaw manifests when processing malformed SOAP messages containing oversized or specially crafted data within the Action, Username, LoginPassword, and Captcha XML fields of the SOAP body. These specific XML elements serve as entry points for exploitation, where the router's stack-based buffer overflow occurs during the HNAP Login action execution. The vulnerability classifies under CWE-121, which describes stack-based buffer overflow conditions, and specifically relates to CWE-772, which addresses insufficient input validation of XML elements. The buffer overflow vulnerability allows an attacker to overwrite adjacent memory locations on the stack, potentially leading to arbitrary code execution or system crashes.
The operational impact of this vulnerability extends beyond simple denial-of-service conditions, as it creates a potential pathway for remote code execution on affected devices. Attackers can craft malicious SOAP requests containing oversized payloads that trigger the buffer overflow, potentially allowing them to execute arbitrary code with the privileges of the router's authentication service. This represents a significant security risk for network infrastructure, as compromised routers can serve as entry points for broader network attacks, enabling man-in-the-middle scenarios, traffic interception, or further lateral movement within the network. The vulnerability affects both authenticated and unauthenticated attack vectors, depending on the specific implementation details of the affected router firmware.
Mitigation strategies for CVE-2016-6563 should prioritize immediate firmware updates from D-Link, as these contain the necessary patches to address the buffer overflow conditions in the SOAP message processing. Network administrators should also implement network segmentation and access control measures to limit exposure, particularly for routers that cannot be immediately updated. The vulnerability aligns with ATT&CK technique T1072, which involves the use of remote services for lateral movement, and T1210, which describes exploitation of remote services through malformed inputs. Additional protective measures include implementing network monitoring to detect anomalous SOAP traffic patterns and disabling unnecessary HNAP services where possible, as the vulnerability specifically targets the HNAP Login action functionality. Organizations should also consider deploying intrusion detection systems capable of identifying malformed SOAP message patterns that could indicate exploitation attempts.