Detect Soliton FileZen OS Command Injection Exploitation (CVE-2026-25108) in Elastic Security
Detects exploitation of CVE-2026-25108, an OS command injection vulnerability (CWE-78) in Soliton Systems K.K FileZen file-sharing appliance. This vulnerability is listed on CISA's Known Exploited Vulnerabilities catalog and allows unauthenticated or authenticated attackers to inject arbitrary OS commands through vulnerable input fields, potentially leading to full system compromise.
MITRE ATT&CK
Elastic Detection Query
sequence by source.ip with maxspan=5m
[network where event.category == "network" and
destination.port in (80, 443, 8080, 8443) and
url.path : ("*/cgi-bin/*", "*/admin/*", "*/upload*", "*/download*") and
(
url.query : ("*;*", "*|*", "*`*", "*$(*)")
or url.original : ("*%3B*", "*%7C*", "*%60*", "*%24%28*")
or url.query : ("*wget*", "*curl*", "*bash*", "*python*", "*nc *", "*chmod*")
)
]
[any where event.category in ("process", "file") and
(
process.name in ("bash", "sh", "dash", "wget", "curl", "nc", "ncat", "python", "python3", "perl")
or file.path : ("/tmp/*", "/var/tmp/*", "/dev/shm/*")
)
]Uses EQL sequence correlation to detect the two-stage pattern of OS command injection: an inbound HTTP request containing shell metacharacters or command keywords to FileZen endpoints, followed within 5 minutes by process or file activity consistent with code execution on the hosting server.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate shell scripts invoked by the FileZen appliance during scheduled maintenance or software updates
- Authorized administrative use of curl or wget from the server itself to fetch updates or configuration
- Security scanning tools that trigger both network request patterns and local process execution during authorized assessments
- Monitoring agents that spawn child processes coincidentally after web traffic spikes
Other platforms for CVE-2026-25108
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 1FileZen-style CGI Command Injection via HTTP GET parameter
Expected signal: Web server access log records GET request to /cgi-bin/upload.cgi with semicolon character in query string. Process audit log shows web server process (httpd/nginx) spawning /bin/sh or /bin/bash as child process executing 'id' command.
- Test 2Post-Exploitation Reverse Shell Download via Injected wget
Expected signal: Web server access log shows POST to /admin/config.cgi with pipe and wget in POST body. Network telemetry shows outbound TCP connection from web server host to ATTACKER_HOST:8080. File creation event for /tmp/payload.sh. Process execution of wget and chmod as children of web server process.
- Test 3Credential and Configuration Exfiltration via Piped cat Command
Expected signal: Web server log records GET request to /download endpoint with URL-encoded pipe and cat command sequence. Network telemetry shows outbound POST connection from FileZen host to ATTACKER_HOST:9090. Process audit captures cat /etc/passwd executed as child of web server process, followed by curl data exfiltration subprocess.
- Test 4Webshell Implantation via Command Injection for Persistent Access
Expected signal: Web server access log records POST to CGI endpoint with semicolon and echo command in body. File creation event for /var/www/html/status.php with PHP content. Process tree shows web server spawning sh executing echo redirection. Subsequent access to /var/www/html/status.php with cmd parameter would indicate webshell usage.
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