CVE-2017-7738 in FortiOS
Summary
by MITRE
An Information Disclosure vulnerability in Fortinet FortiOS 5.6.0 to 5.6.2, 5.4.0 to 5.4.5, 5.2 and below versions allow an admin user with super_admin privileges to view the current SSL VPN web portal session info which may contains user credentials through the fnsysctl CLI command.
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Analysis
by VulDB Data Team • 01/27/2021
The CVE-2017-7738 vulnerability represents a critical information disclosure flaw within Fortinet FortiOS versions ranging from 5.6.0 to 5.6.2, 5.4.0 to 5.4.5, and all versions prior to 5.2. This vulnerability specifically targets the SSL VPN web portal session management functionality and exposes sensitive user authentication data through improper access controls within the system's command-line interface. The flaw is particularly concerning because it allows authenticated administrative users with super_admin privileges to extract session information that may contain user credentials, creating a significant security risk for organizations relying on Fortinet's SSL VPN solutions.
The technical implementation of this vulnerability stems from inadequate privilege separation and insufficient input validation within the fnsysctl CLI command interface. When an administrator with super_admin privileges executes specific commands through this interface, the system inadvertently reveals session details that should remain protected from unauthorized access. This occurs due to the lack of proper access controls that would normally prevent super_admin users from viewing session data that contains potentially sensitive information including user credentials. The vulnerability is classified under CWE-200, which deals with information exposure, and represents a classic case of insufficient access control mechanisms that allow privilege escalation through information disclosure.
The operational impact of this vulnerability extends beyond simple credential exposure, creating potential attack vectors for malicious actors who may have gained administrative access to the FortiOS system. Once an attacker has super_admin privileges, they can leverage this vulnerability to extract session information from active SSL VPN connections, potentially compromising multiple user accounts and their associated credentials. This creates a cascading security risk where a single compromised administrative account can lead to widespread credential exposure across the organization's SSL VPN infrastructure. The vulnerability aligns with ATT&CK technique T1078.004, which covers valid accounts with administrative privileges, and T1566, which involves credential access through network services.
Organizations affected by this vulnerability should immediately implement several mitigation strategies to protect their SSL VPN infrastructure. The primary recommendation involves upgrading to Fortinet FortiOS versions that have addressed this vulnerability, specifically versions 5.2.10, 5.4.8, 5.6.3, and later releases. Additionally, administrators should implement strict access control policies that limit the scope of super_admin privileges and establish monitoring procedures for CLI command execution. Network segmentation and the principle of least privilege should be enforced to minimize the potential impact if administrative credentials are compromised. The vulnerability demonstrates the critical importance of proper privilege management and access control mechanisms in enterprise security infrastructure, particularly within SSL VPN solutions that handle sensitive authentication data. Security teams should also conduct comprehensive audits of their administrative access controls and implement logging of all CLI activities to detect potential exploitation attempts.