CVE-2018-10746 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 a 'get' parameter to the '/userfs/bin/tcapi' binary (in the Diagnostics component) using the 'get <node_name attr>' 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-2018-10746 affects D-Link DSL-3782 EU 1.01 devices and represents a critical buffer overflow flaw within the device's diagnostics component. This issue manifests through the '/userfs/bin/tcapi' binary which processes user input through the 'get <node_name attr>' function, creating a pathway for authenticated attackers to exploit memory corruption vulnerabilities. The flaw stems from inadequate input validation and bounds checking within the command processing mechanism, allowing maliciously crafted buffer inputs to overwrite adjacent memory locations and potentially corrupt program execution flow.
The technical implementation of this vulnerability involves the exploitation of a classic buffer overflow condition in the tcapi binary's handling of the get parameter. When an authenticated user submits a specially crafted long buffer as the get parameter, the system fails to properly validate the input length before processing it through the diagnostics component. This allows attackers to overwrite stack memory or heap structures, potentially leading to arbitrary code execution. The vulnerability specifically targets the memory management routines within the Diagnostics component, which is part of the device's network management framework. The ATT&CK framework categorizes this as a command injection technique under the T1059.001 sub-technique, where adversaries leverage legitimate system tools to execute malicious commands.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables full arbitrary code execution capabilities for authenticated users. This means that once an attacker gains access to the device through legitimate authentication mechanisms, they can leverage this vulnerability to completely compromise the device's functionality. The consequences include potential network infiltration, data exfiltration, and the ability to use the compromised device as a pivot point for attacking other systems within the network. The vulnerability affects the device's core network management functions and represents a significant threat to network security infrastructure. According to CWE classification, this vulnerability maps to CWE-121, which describes stack-based buffer overflow conditions that can lead to arbitrary code execution.
Mitigation strategies for CVE-2018-10746 require immediate attention from network administrators and security teams responsible for managing D-Link DSL-3782 EU 1.01 devices. The most effective immediate solution involves applying the vendor-provided firmware update that addresses the buffer overflow condition in the tcapi binary. Organizations should also implement network segmentation to limit access to these devices and enforce strict authentication controls. Additional defensive measures include monitoring for unusual command execution patterns in the diagnostics component and implementing network intrusion detection systems that can identify potential exploitation attempts. The vulnerability demonstrates the importance of input validation and secure coding practices, particularly in embedded systems where resource constraints may lead to insufficient security controls. Security teams should also consider implementing zero-trust network principles to minimize the impact of potential compromises and reduce the attack surface for similar vulnerabilities.