Detect CVE-2025-64446: Fortinet FortiWeb Path Traversal Exploitation in Google Chronicle
Detects exploitation attempts targeting CVE-2025-64446, a path traversal vulnerability (CWE-23) in Fortinet FortiWeb. This vulnerability allows attackers to traverse directory boundaries and access files outside the intended web root, potentially exposing sensitive configuration files, credentials, or system files. The vulnerability is listed in CISA KEV indicating active exploitation in the wild.
MITRE ATT&CK
YARA-L Detection Query
rule cve_2025_64446_fortiweb_path_traversal {
meta:
author = "df00tech Detection Engineering"
description = "Detects CVE-2025-64446 path traversal exploitation attempts against Fortinet FortiWeb"
severity = "CRITICAL"
priority = "HIGH"
reference = "https://www.fortiguard.com/psirt/FG-IR-25-910"
mitre_attack_tactic = "Initial Access"
mitre_attack_technique = "T1190"
events:
$e.metadata.event_type = "NETWORK_HTTP"
(
$e.principal.application = /(?i)fortiweb/ or
$e.target.application = /(?i)fortiweb/ or
$e.observer.application = /(?i)fortiweb/
)
(
$e.network.http.request_url = /(\.\.\/|\.\.\\/|%2e%2e%2f|%2e%2e\/|\.\.%2f|%2e%2e%5c|%252e%252e|\.\.\.\.\/)/i or
$e.network.http.request_url = /(etc\/passwd|etc\/shadow|web\.config|proc\/self|boot\.ini|win\.ini)/i
)
condition:
$e
}Chronicle YARA-L rule detecting path traversal exploitation attempts against Fortinet FortiWeb via HTTP request URL pattern matching, including URL-encoded traversal sequences and sensitive file targeting.
Data Sources
Required Tables
False Positives & Tuning
- Authorized security assessment activities targeting FortiWeb or protected web applications
- URL rewriting rules on upstream devices that introduce traversal-like sequences before FortiWeb
- Chronicle UDM parsing of non-standard FortiWeb log formats producing incorrect URL fields
- Web application testing frameworks generating traversal patterns as part of normal functional testing
Other platforms for CVE-2025-64446
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Basic Path Traversal Against FortiWeb-Protected Endpoint
Expected signal: FortiWeb access log entry with the traversal URL, source IP, HTTP method GET, and either a 403 block response (if WAF in block mode) or 200/redirect if in monitor mode. SIEM should receive a CommonSecurityLog or syslog event within 60 seconds.
- Test 2URL-Encoded Path Traversal (Double Encoding)
Expected signal: Multiple FortiWeb log entries with percent-encoded URL paths. SIEM events should show the encoded traversal sequences in RequestURL or Message fields. Attack log should show WAF signature matches for each encoded variant.
- Test 3Traversal Targeting FortiWeb Configuration or Certificate Files
Expected signal: FortiWeb access and attack logs showing four separate requests targeting sensitive paths. Response codes expected to be 403 if blocking mode is active. SIEM should receive all four events and score the requests with TargetsSensitiveFile=true, raising FinalScore to critical threshold.
- Test 4Automated Traversal Fuzzing Simulation
Expected signal: Burst of 8 FortiWeb log events from the same source IP within 10 seconds, each containing traversal patterns. SIEM correlation rules should group these by source IP and escalate based on repeat attempts.
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