CVE-2017-17540 in FortiWLC
Summary
by MITRE
The presence of a hardcoded account in Fortinet FortiWLC 8.3.3 allows attackers to gain unauthorized read/write access via a remote shell.
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Analysis
by VulDB Data Team • 02/02/2020
The vulnerability identified as CVE-2017-17540 represents a critical security flaw in Fortinet FortiWLC version 8.3.3, where a hardcoded administrative account exists within the device firmware. This issue stems from poor secure coding practices and inadequate security hardening during the development lifecycle, creating a persistent backdoor that remains active regardless of configuration changes or password updates. The hardcoded account typically contains default credentials that are either publicly known or easily discoverable through reverse engineering of the firmware, providing attackers with a reliable path to compromise the entire wireless controller infrastructure.
The technical implementation of this vulnerability involves a static credential embedded within the device's software code or configuration files, making it impossible to remove or modify through normal administrative procedures. When an attacker gains network access to the FortiWLC device, they can exploit this hardcoded account to establish a remote shell session with full administrative privileges. This remote shell access enables attackers to execute arbitrary commands, modify network configurations, access sensitive data, and potentially use the compromised device as a pivot point for attacking other systems within the network. The vulnerability exists at the authentication layer and represents a fundamental failure in the principle of least privilege, as the account remains active even when all other administrative accounts are properly secured.
The operational impact of this vulnerability extends beyond immediate unauthorized access, as it provides attackers with persistent control over the wireless network infrastructure. This can result in man-in-the-middle attacks, unauthorized network monitoring, data exfiltration, and complete disruption of wireless services. Organizations using affected FortiWLC devices face significant risks including regulatory compliance violations, reputational damage, and potential financial losses due to extended periods of unauthorized access. The vulnerability is particularly dangerous because it operates at the system level, allowing attackers to modify firmware, create new user accounts, and establish persistent backdoors that survive device reboots and configuration changes.
Security professionals should immediately implement mitigations including firmware updates from Fortinet that remove the hardcoded account and address the underlying security flaw. Network segmentation should be implemented to limit access to the wireless controller infrastructure, and strict firewall rules should be configured to restrict remote access to only trusted administrative workstations. The vulnerability aligns with CWE-798, which addresses the use of hard-coded credentials, and represents a common pattern identified in the MITRE ATT&CK framework under the technique of "Valid Accounts" and "Remote Services". Organizations should conduct comprehensive network assessments to identify all instances of the vulnerable FortiWLC firmware and ensure proper patch management procedures are in place to prevent similar issues in future deployments. Additionally, security monitoring should be enhanced to detect unusual authentication patterns and unauthorized access attempts to wireless infrastructure components.