CVE-2016-20017 in DSL-2750B
Summary
by MITRE • 10/19/2022
D-Link DSL-2750B devices before 1.05 allow remote unauthenticated command injection via the login.cgi cli parameter, as exploited in the wild in 2016 through 2022.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/09/2025
The CVE-2016-20017 vulnerability affects D-Link DSL-2750B broadband routers running firmware versions prior to 1.05, representing a critical command injection flaw that enables remote attackers to execute arbitrary commands without authentication. This vulnerability resides within the login.cgi web interface component and specifically targets the cli parameter, which processes user input without proper sanitization or validation. The flaw allows attackers to inject malicious command sequences that are subsequently executed by the underlying operating system, effectively providing a backdoor access mechanism to the device's command shell. The vulnerability was actively exploited in the wild between 2016 and 2022, indicating its significance and the sustained interest from threat actors seeking to compromise these network devices.
The technical nature of this vulnerability aligns with CWE-77 and CWE-94, which categorize it as a command injection flaw where user-supplied input is directly incorporated into system commands without proper validation or escaping mechanisms. The cli parameter in the login.cgi script serves as the attack vector where unfiltered input is passed to shell execution functions, creating an environment where attackers can manipulate the device's operational behavior. This type of vulnerability falls under the ATT&CK technique T1059.001 for command and scripting interpreter, specifically targeting the use of command shells for execution. The vulnerability demonstrates poor input validation practices and inadequate security controls within the web application layer of the router's firmware implementation.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass complete device compromise and potential network infiltration. Once exploited, attackers can gain full administrative control over the affected router, enabling them to modify network configurations, redirect traffic, establish persistent access points, or use the device as a launchpad for further attacks within the local network. The unauthenticated nature of the exploit means that any remote attacker can leverage this vulnerability without requiring valid credentials, making it particularly dangerous for network infrastructure devices. Additionally, the vulnerability's persistence across multiple years of exploitation indicates that many affected devices remained uncompromised due to delayed firmware updates or lack of awareness among network administrators.
Mitigation strategies for CVE-2016-20017 primarily focus on firmware updates and network segmentation measures. Organizations should immediately update all affected D-Link DSL-2750B devices to firmware version 1.05 or later, which contains the necessary patches to address the command injection vulnerability. Network administrators should also implement network segmentation to isolate critical infrastructure from less secure network segments, reducing the potential impact of successful exploitation. Additional protective measures include disabling unnecessary services, implementing proper firewall rules to restrict access to the device's web interface, and conducting regular vulnerability assessments to identify other potentially vulnerable network devices. The vulnerability serves as a reminder of the importance of maintaining current firmware versions and implementing robust network security monitoring to detect unauthorized access attempts.