ESXi Host Prepared for an Unsigned Install

Last updated 2 days ago on 2026-09-30
Created 2 days ago on 2026-09-30

About

Detects three changes on the same ESXi host within 1 hour: SSH enabled, ExecInstalledOnly turned off, and a VIB install with `-f` or `--force` and `--no-sig-check`. Together they open a remote shell, allow unsigned code to run, and bypass VIB signature checks. That sequence prepares the host to receive and run a package the normal controls would reject.
Tags
Domain: EndpointData Source: VMware vSphereUse Case: Threat DetectionTactic: Defense EvasionTactic: Lateral MovementRule Type: ES|QLPlatform: VMware ESXiLanguage: esql
Severity
critical
Risk Score
99
MITRE ATT&CK™

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

Lateral Movement (TA0008)(external, opens in a new tab or window)

False Positive Examples
A documented maintenance window can enable SSH, relax ExecInstalledOnly, and force-install a vendor VIB on the same host. Confirm the change ticket and the VIB name before treating the sequence as malicious.
License
Elastic License v2(external, opens in a new tab or window)

Definition

Integration Pack
Prebuilt Security Detection Rules
Related Integrations

vsphere(external, opens in a new tab or window)

Query
text code block:
FROM logs-vsphere.log-* | WHERE data_stream.dataset == "vsphere.log" AND event.module == "vsphere" and host.ip is not null | EVAL Esql.message_lower = TO_LOWER(message) | EVAL Esql.ssh_enabled = CASE( Esql.message_lower LIKE "*ssh access has been enabled*" OR Esql.message_lower LIKE "*hostsvc/enable_ssh*", 1, 0 ), Esql.exec_installed_only_disabled = CASE( Esql.message_lower LIKE "*execinstalledonly*" AND ( Esql.message_lower LIKE "*false*" OR Esql.message_lower LIKE "* -i 0*" OR Esql.message_lower LIKE "* -v 0*" ), 1, 0 ), Esql.vib_force_install = CASE( Esql.message_lower LIKE "*vib install*" AND ( Esql.message_lower LIKE "* -f *" OR Esql.message_lower LIKE "* -f" OR Esql.message_lower LIKE "* --force *" OR Esql.message_lower LIKE "* --force" ), 1, 0 ) | WHERE Esql.ssh_enabled == 1 OR Esql.exec_installed_only_disabled == 1 OR Esql.vib_force_install == 1 | STATS Esql.ssh_enabled_count = SUM(Esql.ssh_enabled), Esql.exec_installed_only_disabled_count = SUM(Esql.exec_installed_only_disabled), Esql.vib_force_install_count = SUM(Esql.vib_force_install), Esql.message_values = VALUES(message), Esql.log_file_path_values = VALUES(vsphere.log.file.path), Esql.first_seen = MIN(@timestamp), Esql.last_seen = MAX(@timestamp) BY host.ip | WHERE Esql.ssh_enabled_count > 0 AND Esql.exec_installed_only_disabled_count > 0 AND Esql.vib_force_install_count > 0 | KEEP host.ip, Esql.ssh_enabled_count, Esql.exec_installed_only_disabled_count, Esql.vib_force_install_count, Esql.message_values, Esql.log_file_path_values, Esql.first_seen, Esql.last_seen

Install detection rules in Elastic Security

Detect ESXi Host Prepared for an Unsigned Install 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).