Fortinet SSL VPN Exploitation Attempt via Path Traversal in Web Requests (CVE-2018-13379)

Alerts on HTTP requests matching a Fortinet SSL VPN traversal-style query indicative of CVE-2018-13379 exploitation.

FreeReviewedSigma · Critical · v5

Category: webserver
Author: Bhabesh Raj (SigmaHQ), DRL 1.1
Published: 2020-12-08
Updated: 2026-07-31

ATT&CK techniques

Initial Access

Recon
Resource Dev
Initial Access
- T1190Exploit Public-Facing Application
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags web requests targeting Fortinet SSL VPNs that include a specific path traversal pattern combined with a management websession path in the URL query. Such requests matter because they can indicate attempts to reach sensitive internal resources through improperly handled path segments. The detection relies on webserver telemetry capturing the full request URI query string and matching required substrings.

Reporting behind it

Related detections9 linkedT1190 — drag to rearrange

Malicious SharePoint ToolShell Exploitation via ToolPane Endpoint

Malicious Exchange Mailbox Export to ASPX via New-MailboxExportRequest

Suspicious Shell Spawned by ActiveMQ Java Process

Cleo Autorun Exploitation via Healthcheck File Drop

Suspicious SharePoint Worker Process Spawning Command Interpreter via ToolShell

Malicious IIS Worker Process Spawning Command Shell Reconnaissance

Potential StyleSmuggler (CVE-2026-75650) Exploitation Attempt - Magento GraphQL Styles Parameter (via webserver)

Cisco IOS XE Configuration Change by Web UI WSMA User

Possible React2Shell CVE-2025-55182 Prototype Pollution Exploitation

Fortinet SSL VPN Exploitation Attempt via Path Traversal in Web Requests (CVE-2018-13379)

Pivot detection · T1190 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

webserver-request-indicates-fortinet-ssl-vpn-path-traversal-attempt-cve-2018-133-a2e97350

title: Fortinet SSL VPN Exploitation Attempt via Path Traversal in Web Requests (CVE-2018-13379)
id: c0be326a-25dc-4a3e-b7f7-fccacb9aa2e6
status: test
description: This rule flags web requests targeting Fortinet SSL VPNs that include a specific path traversal pattern combined with a management websession path in the URL query. Such requests matter because they can indicate attempts to reach sensitive internal resources through improperly handled path segments. The detection relies on webserver telemetry capturing the full request URI query string and matching required substrings.
references:
  - https://devco.re/blog/2019/08/09/attacking-ssl-vpn-part-2-breaking-the-Fortigate-ssl-vpn/
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2018/Exploits/CVE-2018-13379/web_cve_2018_13379_fortinet_preauth_read_exploit.yml
author: Bhabesh Raj, Huntrule Team
date: 2020-12-08
modified: 2023-01-02
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2018-13379
  - detection.emerging-threats
logsource:
  category: webserver
detection:
  selection:
    cs-uri-query|contains|all:
      - lang=/../../
      - /dev/cmdb/sslvpn_websession
  condition: selection
falsepositives:
  - Unknown
level: critical
license: DRL-1.1
related:
  - id: a2e97350-4285-43f2-a63f-d0daff291738
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

SplunkSPL