CVE-2018-10747 in DSL-3782
Summary
by MITRE
An issue was discovered on D-Link DSL-3782 EU 1.01 devices. An authenticated user can pass a long buffer as an 'unset' parameter to the '/userfs/bin/tcapi' binary (in the Diagnostics component) using the 'unset <node_name>' function and cause memory corruption. Furthermore, it is possible to redirect the flow of the program and execute arbitrary code.
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Analysis
by VulDB Data Team • 02/02/2020
The vulnerability identified as CVE-2018-10747 affects D-Link DSL-3782 EU 1.01 broadband routers and represents a critical buffer overflow flaw within the device's diagnostic functionality. This issue resides in the '/userfs/bin/tcapi' binary component which handles network configuration operations through the Diagnostics module. The vulnerability specifically manifests when an authenticated user submits an excessively long buffer as the 'unset' parameter to the tcapi binary, exploiting a classic buffer overrun condition that can lead to arbitrary code execution.
The technical implementation of this vulnerability stems from inadequate input validation within the tcapi binary's handling of the 'unset <node_name>' function. When processing user-supplied input, the system fails to properly bounds-check the length of the node_name parameter, allowing maliciously crafted input to overflow the allocated memory buffer. This memory corruption directly impacts the program's execution flow, creating opportunities for attackers to manipulate the instruction pointer and redirect program control to execute arbitrary code within the device's memory space. The vulnerability's classification aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers stack-based buffer overflows that can lead to memory corruption and code execution.
The operational impact of this vulnerability extends beyond simple memory corruption, presenting a significant threat to network security infrastructure. An authenticated attacker with access to the device's administrative interface can leverage this flaw to gain full control over the router's operations, potentially enabling man-in-the-middle attacks, network traffic interception, or use as a pivot point for attacking other devices within the local network. The attack vector requires only authentication, which is typically accessible through default credentials or previously compromised accounts, making this vulnerability particularly dangerous for home and small office network environments where device security is often overlooked. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, as the successful exploitation allows for complete system compromise.
Mitigation strategies for CVE-2018-10747 should prioritize immediate firmware updates from D-Link, as the vendor has released patches addressing this specific buffer overflow condition. Network administrators should also implement network segmentation and access controls to limit exposure, ensuring that only authorized personnel can access router management interfaces. Additional defensive measures include disabling unnecessary services, implementing strong authentication mechanisms, and monitoring for unusual network activity that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of input validation in embedded systems and highlights the need for comprehensive security testing of network infrastructure devices, particularly those handling user-provided parameters in network configuration utilities. Organizations should also consider deploying intrusion detection systems to monitor for exploitation attempts targeting known vulnerabilities in network equipment.