Fortinet FortiWeb Vulnerability and Mitigation
.png)
A critical Fortinet FortiWeb vulnerability is currently being exploited in the wild using a public proof-of-concept (PoC). Here are the key details:
What is the flaw?
- It’s an authentication bypass / path traversal vulnerability in FortiWeb WAF.
- Exploitation allows attackers to create new admin accounts without authentication, giving full control of the device.
- The vulnerable endpoint is:
/api/v2.0/cmdb/system/admin%3F/../../../../../cgi-bin/fwbcgi - Attackers send crafted HTTP POST requests to this path with payloads that create admin-level accounts.
Example usernames seen:Testpoint,trader1,trader
Example passwords:3eMIXX43,AFT3$tH4ck,AFT3$tH4ckmet0d4yaga!n. [bleepingcomputer.com]
Affected Versions
- FortiWeb 8.0.1 and earlier are vulnerable.
- Fixed in 8.0.2 (released end of October 2025).
- No official CVE or advisory yet from Fortinet, but multiple security researchers confirmed the exploit works on older versions. [thehackernews.com]
Public Exploit
- A PoC was published by researchers and confirmed by watchTowr Labs.
- A tool called “FortiWeb Authentication Bypass Artifact Generator” was released to help defenders identify vulnerable devices.
- Rapid7 and Defused observed the exploit being sold on black-hat forums and actively used since early October. [securityaffairs.com]
Mitigation
- Update immediately to FortiWeb 8.0.2.
- Remove FortiWeb management interfaces from public internet.
- Check for:
- Unexpected admin accounts.
- Requests to
/fwbcgiin logs. - Indicators of compromise from suspicious IPs (e.g., 107.152.41.19, 144.31.1.63, 185.192.70.0/24). [bleepingcomputer.com]
Why urgent?
- Exploitation is indiscriminate and global.
- Attackers can persist by creating admin accounts.
- If unpatched, assume compromise and perform full incident response. [thehackernews.com]
step-by-step incident response checklist for a suspected FortiWeb compromise via the authentication bypass vulnerability:
1. Immediate Containment
- Disconnect FortiWeb from the internet or restrict management access to trusted IPs only.
- Block suspicious IPs observed in logs (e.g.,
107.152.41.19,144.31.1.63,185.192.70.0/24). - Disable any unnecessary admin accounts immediately.
2. Verify Exploitation
- Check FortiWeb logs for requests to:
/api/v2.0/cmdb/system/admin%3F/../../../../../cgi-bin/fwbcgi - Look for unexpected admin accounts:
- Common attacker-created usernames:
Testpoint,trader1,trader.
- Common attacker-created usernames:
- Review system event logs for configuration changes or new accounts.
3. Preserve Evidence
- Export:
- System logs.
- Web server logs.
- VPN logs (if applicable).
- Take a snapshot or backup of the current configuration for forensic analysis.
4. Eradication
- Update FortiWeb to version 8.0.2 or later (patch released end of October 2025).
- Remove any unauthorized accounts.
- Reset all admin passwords and PSKs.
- Rotate API keys and certificates if used.
5. Recovery
- Re-enable services only after:
- Patch applied.
- Logs reviewed.
- No signs of persistence (e.g., scheduled tasks, scripts).
- Implement network segmentation for management interfaces.
- Enable two-factor authentication for all admin accounts.
6. Post-Incident Actions
- Conduct a full compromise assessment:
- Were configs exfiltrated?
- Were backdoors installed?
- Notify stakeholders and comply with regulatory reporting if required.
- Update SIEM with detection rules:
- Alert on
/fwbcgirequests. - Alert on new admin account creation.
- Alert on
Optional: Detection Rule Example (SIEM)
(event_type:"web" AND url:"/fwbcgi") OR
(event_type:"system" AND action:"create" AND object:"admin account").png)
