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Unlock with Pro - from £29/user/moDetect Apache Tomcat Missing Encryption of Sensitive Data (CVE-2026-34486) in Google Chronicle
Detects potential exploitation or exposure conditions related to CVE-2026-34486, an Apache Tomcat vulnerability (CWE-311: Missing Encryption of Sensitive Data) allowing sensitive data such as credentials, session identifiers, or configuration secrets to be transmitted or stored without adequate encryption. Actively exploited and listed in CISA KEV; associated with CISA BOD 26-04 prioritized remediation guidance. Detection focuses on plaintext transmission of Tomcat-managed credentials/session tokens over unencrypted channels, anomalous access to Tomcat configuration files (server.xml, context.xml, tomcat-users.xml, web.xml) containing sensitive data, and network indicators of cleartext protocol usage to Tomcat listener ports.
MITRE ATT&CK
YARA-L Detection Query
rule cve_2026_34486_tomcat_missing_encryption {
meta:
description = "Detects access to sensitive Tomcat config files or cleartext HTTP to Tomcat ports, consistent with CVE-2026-34486"
severity = "HIGH"
events:
$file.metadata.event_type = "FILE_OPEN"
$file.target.file.full_path = /tomcat-users\.xml|server\.xml|context\.xml|web\.xml/ nocase
$net.metadata.event_type = "NETWORK_HTTP"
$net.target.port = 8080 or $net.target.port = 8009 or $net.target.port = 80
$net.network.tls.established = false
match:
$file.principal.hostname = $net.principal.hostname over 10m
condition:
$file or $net
}Chronicle YARA-L rule correlating sensitive Tomcat configuration file access with cleartext HTTP network sessions on the same host, indicating potential CVE-2026-34486 exploitation or data exposure.
Data Sources
Required Tables
False Positives & Tuning
- Config management agents legitimately reading files as part of scheduled compliance checks
- Internal segmented networks where cleartext HTTP is an accepted risk behind other controls
- Duplicate detections from multiple EDR sensors on the same host
Other platforms for CVE-2026-34486
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 1Simulate cleartext credential exposure in tomcat-users.xml
Expected signal: File creation and read events for tomcat-users.xml containing plaintext credential strings
- Test 2Simulate cleartext HTTP request to Tomcat port
Expected signal: Network connection event to destination port 8080 using HTTP protocol without TLS
- Test 3Simulate access to Tomcat server.xml configuration file
Expected signal: DeviceProcessEvents/DeviceFileEvents showing PowerShell reading server.xml with connector definitions
- Test 4Simulate AJP cleartext connector probe
Expected signal: Network connection attempt logged to destination port 8009 (AJP) without TLS negotiation
References (4)
- https://lists.apache.org/thread/9510k5p5zdvt9pkkgtyp85mvwxo2qrly
- 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-2026-34486
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