Detect Mirasvit Full Page Cache Warmer Deserialization RCE (CVE-2026-45247) in Splunk
Detects exploitation of CVE-2026-45247, a deserialization of untrusted data vulnerability in the Mirasvit Full Page Cache Warmer Magento extension. Successful exploitation allows remote attackers to execute arbitrary code by sending crafted serialized PHP objects to vulnerable endpoints. This CVE is listed in CISA KEV, indicating active exploitation in the wild.
MITRE ATT&CK
- Tactic
- Initial Access Execution Persistence
SPL Detection Query
index=web OR index=iis OR index=apache sourcetype IN (iis, apache_access, nginx_access, ms:iis:auto)
(uri_path="*/cache-warmer*" OR uri_path="*/mirasvit*cachewarmer*" OR uri_path="*/cachewarmer*")
method IN (POST, PUT)
| eval payload_size=coalesce(bytes, cs_bytes, 0)
| eval suspicious_payload=if(match(uri_query, "(O:|C:|rO0|YTo|Tzo)") OR payload_size > 5000, 1, 0)
| eval post_body_suspicious=if(match(form_data, "(O:|C:|rO0|php|eval|base64)"), 1, 0)
| where suspicious_payload=1 OR post_body_suspicious=1
| stats count as request_count, values(src_ip) as source_ips, min(_time) as first_seen, max(_time) as last_seen, values(status) as http_statuses, values(uri_path) as uris by host, src_ip
| eval risk_score=case(request_count > 10, 90, request_count > 5, 70, true(), 50)
| where request_count >= 1
| sort -risk_scoreSearches web access logs for POST/PUT requests to Mirasvit cache warmer endpoints with serialized PHP object patterns or oversized payloads indicative of deserialization exploitation attempts.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Automated cache warming jobs that legitimately POST to warmer endpoints
- Penetration testing tools scanning the Magento application
- Large legitimate POST payloads to cache endpoints during normal operation
- Third-party Magento extensions that interact with the cache warmer API
Other platforms for CVE-2026-45247
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 Deserialization Probe to Cache Warmer Endpoint
Expected signal: POST request to /mirasvit/cachewarmer/collect visible in web access logs with payload containing 'O:8:' serialization marker; HTTP response code logged
- Test 2PHP Deserialization Gadget Chain Simulation (Lab)
Expected signal: PHP CLI process spawned with command-line containing unserialize() — visible in auditd execve records or CrowdStrike process telemetry
- Test 3Web Shell Drop Simulation Following Deserialization RCE
Expected signal: File creation event in /var/www/html/pub/ for a .php file by the web server user (www-data or nginx); auditd CREATE record or Falcon sensor file event
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