Azure WireServer OpenSSL Certificate Decrypt or LinuxTransport Generation

Last updated 2 days ago on 2026-09-10

Created a month ago on 2026-08-17

About

Identifies OpenSSL generating a CN=LinuxTransport certificate or decrypting CMS/PKCS7 payloads with a key that is not the Azure Linux Agent certificate under /var/lib/waagent. Adversaries can scrape WireServer certificates, mint a LinuxTransport identity, and decrypt extension protectedSettings with openssl cms -decrypt or smime -decrypt.

Tags

Domain: EndpointDomain: CloudOS: LinuxUse Case: Threat DetectionPlatform: AzurePlatform: LinuxTactic: Credential AccessTactic: Defense EvasionData Source: Elastic DefendLanguage: eql

Severity

medium

Risk Score

MITRE ATT&CK™

Credential Access (TA0006)(external, opens in a new tab or window)

↳ Unsecured Credentials (T1552)(external, opens in a new tab or window)

Defense Evasion (TA0005)(external, opens in a new tab or window)

↳ Deobfuscate/Decode Files or Information (T1140)(external, opens in a new tab or window)

False Positive Examples

Custom configuration-management that decrypts CMS blobs with an organization key outside /var/lib/waagent. Confirm the key path and exclude the specific command line after review.

License

Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type: Event Correlation Rule
Integration Pack: Prebuilt Security Detection Rules
Index Patterns: logs-endpoint.events.process-*
Related Integrations: endpoint(external, opens in a new tab or window)
Query

✄𐘗text code block:
✄𐘗process where host.os.type == "linux" and event.type == "start" and
event.action in ("exec", "exec_event", "start") and process.name == "openssl" and
(
  (
    process.args in ("cms", "smime") and process.args == "-decrypt"
  ) or
  (
    process.args == "req" and process.args : "*LinuxTransport*"
  )
) and
not process.args like "/var/lib/waagent/*" and
not process.parent.executable like (
  "/usr/sbin/waagent",
  "/usr/bin/waagent"
)

Install detection rules in Elastic Security

Detect Azure WireServer OpenSSL Certificate Decrypt or LinuxTransport Generation in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).