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CVE-2026-34486 Elastic Security · Elastic

Detect Apache Tomcat Missing Encryption of Sensitive Data (CVE-2026-34486) in Elastic Security

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

Tactic
Credential Access Collection Initial Access

Elastic Detection Query

Elastic Security (Elastic)
eql
sequence by host.name with maxspan=10m
  [file where event.action == "open" and file.name : ("tomcat-users.xml","server.xml","context.xml","web.xml")]
  [network where destination.port in (8080,8009,80) and network.protocol == "http" and not tls.established == true]
medium severity low confidence

Correlates local file access to Tomcat configuration files with subsequent cleartext HTTP network activity, suggesting exfiltration or exploitation attempts related to CVE-2026-34486.

Data Sources

Elastic Endpoint (file)Elastic Endpoint (network)

Required Tables

filenetwork

False Positives & Tuning

  • Legitimate config backup jobs followed by unrelated HTTP traffic within the time window
  • Development environments with mixed TLS/non-TLS testing
  • Monitoring agents polling both filesystem and network 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.

  1. Test 1Simulate cleartext credential exposure in tomcat-users.xml

    Expected signal: File creation and read events for tomcat-users.xml containing plaintext credential strings

  2. Test 2Simulate cleartext HTTP request to Tomcat port

    Expected signal: Network connection event to destination port 8080 using HTTP protocol without TLS

  3. Test 3Simulate access to Tomcat server.xml configuration file

    Expected signal: DeviceProcessEvents/DeviceFileEvents showing PowerShell reading server.xml with connector definitions

  4. Test 4Simulate AJP cleartext connector probe

    Expected signal: Network connection attempt logged to destination port 8009 (AJP) without TLS negotiation

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