CVE-2016-5681 in DIR-800
Summary
by MITRE
Stack-based buffer overflow in dws/api/Login on D-Link DIR-850L B1 2.07 before 2.07WWB05, DIR-817 Ax, DIR-818LW Bx before 2.05b03beta03, DIR-822 C1 3.01 before 3.01WWb02, DIR-823 A1 1.00 before 1.00WWb05, DIR-895L A1 1.11 before 1.11WWb04, DIR-890L A1 1.09 before 1.09b14, DIR-885L A1 1.11 before 1.11WWb07, DIR-880L A1 1.07 before 1.07WWb08, DIR-868L B1 2.03 before 2.03WWb01, and DIR-868L C1 3.00 before 3.00WWb01 devices allows remote attackers to execute arbitrary code via a long session cookie.
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Analysis
by VulDB Data Team • 11/02/2024
The vulnerability identified as CVE-2016-5681 represents a critical stack-based buffer overflow flaw located within the dws/api/Login component of various D-Link wireless routers and networking devices. This security weakness affects multiple models including the DIR-850L B1, DIR-817 Ax, DIR-818LW Bx, DIR-822 C1, DIR-823 A1, DIR-895L A1, DIR-890L A1, DIR-885L A1, DIR-880L A1, DIR-868L B1, and DIR-868L C1 device lines. The flaw manifests specifically when processing session cookies, creating a remote code execution vector that can be exploited by attackers without requiring authentication. This vulnerability falls under the Common Weakness Enumeration category CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The affected firmware versions span across several major releases, indicating a widespread issue that impacts numerous consumer and small office networking devices.
The technical exploitation of this vulnerability occurs through a carefully crafted session cookie that exceeds the allocated buffer space within the dws/api/Login handler. When the device processes this oversized cookie, the stack memory layout becomes corrupted, potentially allowing an attacker to overwrite return addresses, function pointers, or other critical memory segments. This memory corruption can be leveraged to redirect program execution flow and ultimately achieve arbitrary code execution on the affected device. The attack vector is particularly concerning as it operates over the network without requiring physical access or prior authentication, making it a significant threat to network security. The vulnerability's impact extends beyond simple code execution, as successful exploitation could allow attackers to gain full administrative control over the affected routers, potentially enabling man-in-the-middle attacks, DNS hijacking, or the establishment of persistent backdoors within the network infrastructure.
The operational consequences of this vulnerability pose severe risks to both individual users and enterprise network environments. Network administrators face the challenge of managing numerous affected devices across their infrastructure, many of which may be deployed in remote locations or managed by end users who lack technical expertise. The potential for attackers to gain unauthorized access to router configurations means that sensitive network information could be compromised, including login credentials, network topology details, and communication patterns. This vulnerability directly aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1021.001 for Remote Services, as exploitation enables attackers to execute commands remotely and establish persistent access to network services. The affected devices typically serve as gateways for network traffic, making them prime targets for attackers seeking to establish footholds within larger network environments or to conduct advanced persistent threat operations.
Mitigation strategies for CVE-2016-5681 require immediate firmware updates from D-Link, as the vulnerability cannot be effectively addressed through network-level configurations or firewall rules. Organizations should prioritize patching all affected devices, particularly those with exposed services or those located in critical network segments. Network segmentation and monitoring can provide additional layers of defense by limiting the potential impact of successful exploitation, though these measures do not eliminate the underlying vulnerability. Security teams should implement continuous monitoring for unusual network traffic patterns or unauthorized configuration changes that might indicate exploitation attempts. The vulnerability highlights the importance of firmware security testing and the need for manufacturers to implement proper input validation and memory management practices. Additionally, network administrators should consider implementing network access control lists and intrusion detection systems to identify and block suspicious session cookie patterns that might indicate attempted exploitation of this vulnerability.