CVE-2020-28347 in Archer A7 AC1750
Summary
by MITRE • 11/09/2020
tdpServer on TP-Link Archer A7 AC1750 devices before 201029 allows remote attackers to execute arbitrary code via the slave_mac parameter. NOTE: this issue exists because of an incomplete fix for CVE-2020-10882 in which shell quotes are mishandled.
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Analysis
by VulDB Data Team • 12/03/2020
The vulnerability identified as CVE-2020-28347 affects the tdpServer component within TP-Link Archer A7 AC1750 wireless routers running firmware versions prior to 201029. This represents a critical remote code execution flaw that enables attackers to gain unauthorized control over affected devices through manipulation of the slave_mac parameter. The vulnerability stems from inadequate input validation and improper shell command construction within the router's web interface handling mechanism. The issue is particularly concerning as it allows remote attackers to execute arbitrary code without requiring authentication, potentially enabling full device compromise and subsequent network infiltration.
This vulnerability manifests as a classic command injection flaw where the slave_mac parameter is improperly sanitized before being passed to shell commands. The root cause lies in the incomplete remediation of CVE-2020-10882, where developers failed to properly address shell quote handling mechanisms. The flawed implementation allows attackers to inject malicious shell commands through the parameter, which are then executed with the privileges of the web server process. This type of vulnerability maps directly to CWE-77 and CWE-94 in the Common Weakness Enumeration catalog, representing improper neutralization of special elements used in command execution and execution of code from external input. The ATT&CK framework categorizes this under T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation.
The operational impact of this vulnerability extends beyond individual device compromise to potential network-wide infiltration. Once an attacker gains remote code execution capability, they can establish persistent backdoors, modify router configurations, redirect traffic, or use the compromised device as a pivot point for attacking other network segments. The affected TP-Link Archer A7 AC1750 devices are widely deployed in residential and small office environments, making them attractive targets for cybercriminals seeking to establish footholds within networks. The vulnerability's remote nature eliminates the need for physical access or network proximity, allowing attackers to exploit devices from anywhere on the internet.
Mitigation strategies must address both immediate remediation and long-term security hardening. The primary solution involves updating to firmware version 201029 or later, which contains the proper fix for the shell quote handling issue. Network administrators should also implement network segmentation to limit the potential impact of device compromise, deploy intrusion detection systems to monitor for suspicious network activity, and consider disabling unnecessary services. Additional defensive measures include implementing web application firewalls to filter malicious input, conducting regular security audits of network devices, and establishing robust patch management processes. The vulnerability highlights the critical importance of proper input validation and secure coding practices, particularly when handling user-supplied data in shell command contexts. Organizations should also consider implementing zero-trust network architectures to minimize the potential damage from compromised devices and ensure comprehensive network visibility to detect anomalous behavior.