CVE-2021-26105
📋 TL;DR
This CVE describes a stack-based buffer overflow vulnerability in FortiSandbox's profile parser that allows authenticated attackers to execute arbitrary code via crafted HTTP requests. Affected systems include FortiSandbox versions 3.2.2 and below, and 3.1.4 and below. Successful exploitation could lead to complete system compromise.
💻 Affected Systems
- FortiSandbox
📦 What is this software?
Fortisandbox by Fortinet
Fortisandbox by Fortinet
Fortisandbox by Fortinet
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with administrative privileges, allowing attacker to install persistent backdoors, exfiltrate sensitive data, and pivot to other network segments.
Likely Case
Unauthorized code execution within the FortiSandbox application context, potentially leading to sandbox bypass, data theft, and lateral movement within the security infrastructure.
If Mitigated
Limited impact due to network segmentation and strict access controls, potentially resulting in denial of service or application crash only.
🎯 Exploit Status
Exploitation requires authentication and specific knowledge of the profile parser functionality
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: FortiSandbox 3.2.3 or 3.1.5 and above
Vendor Advisory: https://fortiguard.fortinet.com/psirt/FG-IR-20-234
Restart Required: Yes
Instructions:
1. Download the latest firmware from Fortinet support portal. 2. Backup current configuration. 3. Apply firmware update via web interface or CLI. 4. Reboot the appliance. 5. Verify successful update.
🔧 Temporary Workarounds
Restrict Management Access
allLimit access to FortiSandbox management interface to trusted IP addresses only
config system interface
edit <interface_name>
set allowaccess https ssh
set trust-ip-1 <trusted_ip>
end
Enable Strict Authentication
allImplement multi-factor authentication and strong password policies for all administrative accounts
config system admin
edit <admin_user>
set two-factor disable
set password <strong_password>
end
🧯 If You Can't Patch
- Implement strict network segmentation to isolate FortiSandbox from critical systems
- Deploy additional monitoring and intrusion detection on FortiSandbox management traffic
🔍 How to Verify
Check if Vulnerable:
Check FortiSandbox firmware version via web interface (System > Dashboard) or CLI command: get system statusCheck Version:
get system status | grep VersionVerify Fix Applied:
Verify firmware version is 3.2.3 or higher, or 3.1.5 or higher after patching📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to profile parsing endpoints
- Multiple failed authentication attempts followed by successful login
- Process crashes or restarts of FortiSandbox services
Network Indicators:
- Unusual outbound connections from FortiSandbox appliance
- HTTP traffic patterns matching exploit payloads to management interface
SIEM Query:
source="fortisandbox" AND (event_type="http_request" AND uri="*profile*" AND size>10000) OR (event_type="auth" AND result="success" AND source_ip NOT IN [trusted_ips])