Detect Trend Micro Apex One Directory Traversal Exploitation (CVE-2026-34926) in Google Chronicle
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
YARA-L Detection Query
rule cve_2026_34926_apex_one_directory_traversal {
meta:
author = "df00tech Detection Engineering"
description = "Detects directory traversal exploitation of Trend Micro Apex One CVE-2026-34926"
severity = "CRITICAL"
priority = "HIGH"
reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-34926"
mitre_attack_tactic = "Initial Access"
mitre_attack_technique = "T1190"
events:
$req.metadata.event_type = "NETWORK_HTTP"
$req.network.http.method != ""
(
re.regex($req.network.http.request_url, `(?i)(\.\.|%2e%2e|%252e|\.\.%2f|\.\.%5c)`) and
re.regex($req.network.http.request_url, `(?i)(\/officescan|\/apex_one|\/OfficeScan|\/widget|\/ServerMigration)`)
)
match:
$req.principal.ip over 5m
condition:
#req >= 2
}Chronicle YARA-L rule detecting repeated directory traversal requests to Trend Micro Apex One endpoints. Triggers on two or more traversal-pattern HTTP requests from the same source IP within 5 minutes.
Data Sources
Required Tables
False Positives & Tuning
- Authorized red team exercises targeting Apex One as part of a scoped engagement
- Apex One self-update processes that generate encoded URL requests to internal endpoints
- Third-party integrations that interact with Apex One API using non-standard URL encoding
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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