CVE-2021-26102 in FortiWAN
Summary
by MITRE • 12/19/2024
A relative path traversal vulnerability (CWE-23) in FortiWAN version 4.5.7 and below, 4.4 all versions may allow a remote non-authenticated attacker to delete files on the system by sending a crafted POST request. In particular, deleting specific configuration files will reset the Admin password to its default value.
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Analysis
by VulDB Data Team • 01/22/2025
This vulnerability represents a critical relative path traversal flaw that exists within FortiWAN network management software versions 4.5.7 and earlier, as well as all versions of the 4.4 release line. The issue stems from inadequate input validation in the web interface handling of file operations, specifically when processing POST requests containing file path parameters. Attackers can exploit this weakness by crafting malicious requests that manipulate the relative path references to target system files outside of intended directories. The vulnerability falls under CWE-23, which categorizes path traversal attacks as a fundamental security flaw where an attacker can access files and directories that are stored outside the web root folder. This particular implementation allows for arbitrary file deletion operations without requiring authentication, making it particularly dangerous for network administrators who may not immediately detect such unauthorized modifications.
The operational impact of this vulnerability extends beyond simple file deletion capabilities to include complete administrative control over the affected FortiWAN system. When attackers successfully exploit this vulnerability, they can target and remove specific configuration files that govern the system's administrative access controls. The most significant consequence occurs when the admin password configuration file is deleted, as this action resets the administrative credentials to their default values, effectively providing attackers with full administrative access to the network management system. This reset mechanism creates a persistent backdoor that allows attackers to maintain control over the network infrastructure without requiring additional authentication credentials. The vulnerability affects the core functionality of the FortiWAN system by undermining its authentication and authorization mechanisms, potentially leading to complete network compromise.
Security professionals should recognize this vulnerability as a prime example of how insufficient input validation can lead to severe privilege escalation and system compromise scenarios. The attack vector operates entirely through HTTP POST requests, making it accessible to remote attackers without requiring physical access or prior authentication. This characteristic aligns with ATT&CK technique T1078.004 which covers valid accounts and T1566.002 which involves spearphishing with a malicious attachment or link. Organizations using FortiWAN software should immediately implement network segmentation and access controls to limit exposure to this vulnerability, while also deploying web application firewalls to detect and block malicious path traversal attempts. The vulnerability demonstrates the critical importance of proper input sanitization and the principle of least privilege in network management systems, as it allows attackers to bypass normal access controls through manipulation of file path parameters. Immediate patching of affected systems is essential to prevent exploitation and maintain network security posture.
This vulnerability represents a significant risk to enterprise network infrastructure as it combines remote exploitation capabilities with privilege escalation potential through simple file deletion operations. The fact that authentication is not required makes it particularly dangerous for systems that are exposed to untrusted networks or internet-facing interfaces. Network administrators should conduct thorough vulnerability assessments to identify all instances of affected FortiWAN versions and implement appropriate mitigations including access control lists, network monitoring, and immediate patch deployment. The vulnerability also highlights the need for robust configuration management practices and regular security audits to prevent unauthorized modifications to critical system files that could lead to complete system compromise and unauthorized network access.