CVE-2018-3950 in TL-R600VPN
Summary
by MITRE
An exploitable remote code execution vulnerability exists in the ping and tracert functionality of the TP-Link TL-R600VPN HWv3 FRNv1.3.0 and HWv2 FRNv1.2.3 http server. A specially crafted IP address can cause a stack overflow, resulting in remote code execution. An attacker can send a single authenticated HTTP request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 06/12/2023
The vulnerability CVE-2018-3950 represents a critical remote code execution flaw affecting TP-Link TL-R600VPN routers with specific hardware and firmware versions. This vulnerability resides within the network diagnostic utilities of the router's web interface, specifically targeting the ping and tracert functions that are commonly used for network troubleshooting. The issue manifests when the router processes specially crafted IP addresses through these diagnostic commands, creating a condition where user-supplied input is not properly validated or sanitized before being processed by the underlying system functions.
The technical root cause of this vulnerability stems from improper input validation within the web server implementation of the affected TP-Link routers. When a user submits a malformed IP address through the ping or tracert functionality, the router's http server fails to properly bounds-check the input data before passing it to stack-based functions. This lack of input sanitization creates a classic stack buffer overflow condition where maliciously crafted input exceeds the allocated buffer space, overwriting adjacent memory locations including return addresses and control data. The vulnerability is particularly dangerous because it requires only a single authenticated HTTP request to exploit, meaning an attacker who has gained access to the router's administrative interface can execute arbitrary code remotely.
From an operational perspective, this vulnerability presents significant risk to network security infrastructure as it allows attackers to gain full control over the affected routers. The exploitation process requires minimal privileges since the vulnerability is triggered through the web interface, which typically requires authentication. Once successfully exploited, attackers can execute arbitrary commands with the privileges of the web server process, potentially leading to complete system compromise, data exfiltration, or use of the compromised router as a pivot point for attacking other devices on the network. The vulnerability affects both hardware version 3 with firmware version 1.3.0 and hardware version 2 with firmware version 1.2.3, indicating this was a widespread issue across multiple router models.
The vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which is classified under the Common Weakness Enumeration framework as a fundamental software flaw where data is written beyond the bounds of a stack buffer. This weakness is particularly dangerous in network appliances because it can be exploited remotely without requiring physical access to the device. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1059.007 Command and Scripting Interpreter: PowerShell, as attackers can execute arbitrary commands through the compromised router's command execution interface. The authentication requirement for exploitation places this vulnerability in the context of credential compromise or social engineering attacks, as attackers must first obtain valid administrative credentials to trigger the vulnerability.
Mitigation strategies for CVE-2018-3950 should focus on immediate firmware updates from TP-Link to address the buffer overflow conditions in the web server implementation. Network administrators should also implement strict access controls and monitoring of the router's web interface to detect unauthorized access attempts. Additional security measures include disabling unnecessary services, implementing network segmentation to limit lateral movement, and deploying intrusion detection systems to monitor for exploitation attempts. Regular security audits of network infrastructure should include verification of firmware versions and patch management processes to prevent similar vulnerabilities from remaining unaddressed. Organizations should also consider implementing network access control lists to restrict access to router management interfaces to trusted administrative workstations only.