Fortinet FortiOS and FortiProxy SSL VPN Improper Authorization Vulnerability (CVE-2018-13382) Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTFortiOS 6.0.0 to 6.0.4, 5.6.0 to 5.6.8, 5.4.1 to 5.4.10, and FortiProxy 1.0/1.1/1.2/2.0 series
An unauthenticated remote attacker can modify the password of any SSL VPN web portal user via specially crafted HTTP requests, leading to unauthorized network access
Immediately upgrade the firmware to the patched versions, or restrict/disable the SSL VPN web portal service as a temporary workaround
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the official firmware updates provided by Fortinet. Verify your current version and perform the upgrade via CLI as shown below:
# Check current FortiOS version
get system status
# Example command to restore/upgrade firmware image via TFTP
execute restore image tftp FGT_60E-v6.0.5-build0268-FORTINET.out 192.168.1.102. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict access to the SSL VPN portal by configuring source IP address limitations or disabling the web portal interface.
# Restrict SSL VPN access to trusted IP ranges only
config vpn ssl settings
set source-interface 'wan1'
set source-address 'Trusted_IP_Range'
set status enable
end3. Log Audit & IoC Verification Commands
Audit the system logs to identify unauthorized password modification attempts or suspicious activities originating from external IPs.
# Filter and display event logs related to password changes
show log disk filter
set category event
set severity warning
end
execute log filter category 1
execute log display | grep -i 'password'Stop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2018-13382) is an improper authorization flaw (CWE-863) within the SSL VPN web portal component of Fortinet FortiOS and FortiProxy. The root cause lies in the lack of proper identity and session validation during password modification requests. Consequently, the system processes password change requests without verifying if the requester is authenticated or authorized to perform the action.
2. Exploitation Mechanics & Attack Scenario
An attacker can exploit this vulnerability by sending a specially crafted HTTP POST request directly to the password change endpoints (such as /remote/logincheck or /remote/changepassword). Because the application fails to validate the session state or require the current password, it accepts the parameters containing the target username and the new password, updating the user credentials in the system database. This allows trivial, unauthenticated password resets.
3. Infrastructure & Business Impact
As a vulnerability listed in the CISA KEV catalog, this flaw has been actively exploited in the wild by various threat actors. Successful exploitation grants attackers initial access to the enterprise network via the compromised SSL VPN account. This can lead to lateral movement, sensitive data exfiltration, ransomware deployment, and severe disruption of business operations.
Official Vendor Advisories & References
An Improper Authorization vulnerability in Fortinet FortiOS 6.0.0 to 6.0.4, 5.6.0 to 5.6.8 and 5.4.1 to 5.4.10 and FortiProxy 2.0.0, 1.2.0 to 1.2.8, 1.1.0 to 1.1.6, 1.0.0 to 1.0.7 under SSL VPN web portal allows an unauthenticated attacker to modify the password of an SSL VPN web portal user via specially crafted HTTP requests
Frequently Asked SecOps Questions (CVE-2018-13382)
FAQQ1. How critical is CVE-2018-13382 and is it actively exploited in the wild?
CVE-2018-13382 is rated CVSS 7.5 (HIGH) with a 30-day EPSS exploitation probability of 81.7%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2018-13382?
Primary impacted vendors include fortinet across fortios, fortiproxy. Scope summary: FortiOS 6.0.0 to 6.0.4, 5.6.0 to 5.6.8, 5.4.1 to 5.4.10, and FortiProxy 2.0.0, 1.2.0 to 1.2.8, 1.1.0 to 1.1.6, 1.0.0 to 1.0.7
Q3. What temporary mitigations or workarounds exist for CVE-2018-13382 before patching?
[Mitigation] Immediately upgrade the firmware to the patched versions, or restrict/disable the SSL VPN web portal service as a temporary workaround Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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