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Upgrade to ProDetect Fortinet FortiSandbox OS Command Injection (CVE-2026-25089) in Microsoft Sentinel
Detects potential exploitation of CVE-2026-25089, an OS command injection vulnerability (CWE-78) in Fortinet FortiSandbox that allows an authenticated or remote attacker to execute arbitrary commands on the underlying operating system via crafted input to a vulnerable API/web endpoint. This vulnerability is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog and is subject to BOD 26-04 prioritized remediation timelines. Detection focuses on anomalous shell/process execution spawned from FortiSandbox web/management processes, suspicious HTTP requests containing shell metacharacters against FortiSandbox management interfaces, and post-exploitation command execution artifacts.
MITRE ATT&CK
KQL Detection Query
// Requires firewall/network device logs or FortiSandbox syslog forwarded via CEF/Syslog connector into a custom table (FortiSandboxCL) or CommonSecurityLog
let susPatterns = dynamic([";", "|", "&&", "$(", "`", "wget ", "curl ", "/bin/sh", "/bin/bash", "nc ", "chmod +x"]);
CommonSecurityLog
| where DeviceVendor == "Fortinet" and DeviceProduct has "FortiSandbox"
| where isnotempty(RequestURL) or isnotempty(Message)
| extend RawContent = strcat(tostring(RequestURL), " ", tostring(Message))
| where susPatterns has_any (RawContent)
| extend MatchedPattern = extract_all(@"(;|\||&&|\$\(|`|wget |curl |/bin/sh|/bin/bash|nc |chmod \+x)", RawContent)
| project TimeGenerated, DeviceVendor, DeviceProduct, SourceIP, DestinationIP, RequestURL, Message, MatchedPattern
| sort by TimeGenerated descDetects HTTP requests or syslog messages to/from FortiSandbox devices containing shell metacharacters or common command-injection payload fragments consistent with CVE-2026-25089 exploitation attempts.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate administrative scripts that pass URL-encoded special characters as part of normal configuration tasks
- Security scanners/vulnerability assessment tools performing authorized testing against FortiSandbox
- Third-party integrations pushing crafted payloads for legitimate file analysis submissions
Other platforms for CVE-2026-25089
Testing Methodology
Validate this detection against 3 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 1Simulate command injection payload in HTTP request
Expected signal: HTTP access log entry on the FortiSandbox lab appliance (or reverse proxy) showing the request URL with embedded shell metacharacters
- Test 2Simulate payload download via wget from web-server-spawned shell
Expected signal: Process creation event showing wget spawned as a child of a web-server user/process, with associated CommandLine and ParentBaseFileName
- Test 3Simulate reverse shell command execution pattern
Expected signal: Process creation log/EDR telemetry showing sh -c invocation with an unusual parent process (web server user context)
References (4)
- https://fortiguard.fortinet.com/psirt/FG-IR-26-141
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-25089
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