Detect Trend Micro Apex One Directory Traversal Exploitation (CVE-2026-34926) in Splunk
Detects exploitation attempts targeting CVE-2026-34926, a directory traversal vulnerability (CWE-23) in Trend Micro Apex One (On-Premise). This KEV-listed vulnerability allows unauthenticated or low-privileged attackers to traverse directory boundaries via crafted HTTP requests to the Apex One management server, potentially enabling arbitrary file read or write operations. Active exploitation has been observed in the wild.
MITRE ATT&CK
SPL Detection Query
index=web OR index=iis OR index=proxy sourcetype=iis OR sourcetype=access_combined OR sourcetype=pan:traffic
| eval uri=coalesce(cs_uri_stem, uri_path, request)
| eval query=coalesce(cs_uri_query, uri_query, "")
| eval full_uri=uri."?".query
| where (match(full_uri, "(\.\.|%2e%2e|%252e%252e|\.\.%2f|\.\.\/|\.\.%5c)") AND match(uri, "(?i)(\/officescan|\/apex_one|\/OfficeScan|\/widget\/widgetMeta\.php|\/ServerMigration|\/ServerName)"))
| eval traversal_depth=mvcount(split(full_uri, ".."))-1
| where traversal_depth >= 2
| stats count AS attempt_count, values(full_uri) AS traversal_uris, values(status) AS response_codes, dc(clientip) AS unique_src BY clientip, host, _time
| sort -attempt_countSplunk detection for directory traversal attempts against Trend Micro Apex One On-Premise management endpoints. Correlates IIS and proxy logs for encoded traversal patterns in known Apex One URL paths.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Automated vulnerability scanners (Rapid7, Qualys) performing scheduled scans of the Apex One server
- URL encoding edge cases in browser-generated requests to the management portal
- Internal IT tooling that proxies requests through Apex One management interfaces
Other platforms for CVE-2026-34926
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 1Basic Directory Traversal Probe Against Apex One CGI Endpoint
Expected signal: IIS access log entry with traversal sequence in cs-uri-query field, HTTP response code indicating success (200) or path not found (404). Network connection event from test host to Apex One server on port 4343.
- Test 2Double-Encoded Traversal Bypass Attempt
Expected signal: Multiple IIS access log entries with different traversal encoding variants. Possible WAF alert if WAF is deployed. Network events showing rapid sequential HTTP requests to Apex One from the same source IP.
- Test 3Windows Apex One Traversal Simulation via PowerShell
Expected signal: Windows Security Event Log entry for PowerShell execution (Event ID 4688 or Sysmon Event ID 1). Network connection events from the Windows test host to Apex One server port 4343. IIS access log entries on Apex One server matching traversal patterns.
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