Detect Hypervisor CLI in CrowdStrike LogScale
Adversaries may abuse hypervisor command line interpreters (CLIs) to execute malicious commands. Hypervisor CLIs enable functionality for managing both the hypervisor and guest virtual machines. On ESXi systems, tools such as esxcli and vim-cmd allow administrators to configure firewall rules, manage log forwarding, list/start/stop virtual machines, and more. Adversaries leverage these tools for discovery, VM termination (ransomware), firewall manipulation, and persistence. UNC3886 used esxcli extensively for malware installation and artifact removal. Ransomware families including Cheerscrypt, Royal, and BlackBasta use esxcli to enumerate and terminate VMs before encryption.
MITRE ATT&CK
- Tactic
- Execution
- Technique
- T1059 Command and Scripting Interpreter
- Sub-technique
- T1059.012 Hypervisor CLI
- Canonical reference
- https://attack.mitre.org/techniques/T1059/012/
LogScale Detection Query
#event_simpleName = ProcessRollup2
| ImageFileName = /(\/sbin\/esxcli|\/bin\/vim-cmd|esxcfg-)/ OR FileName in ("esxcli", "vim-cmd")
| CommandLine = /(vm process kill|vm process list|vmsvc\/power\.off|vmsvc\/getallvms|system maintenanceMode|network firewall|software vib install|software vib remove|software acceptance set|system syslog|system settings advanced|hostsvc\/enable_ssh|hostsvc\/start_ssh|solo\/registervm|\.vmdk|\.vmsd|\.vmsn|chmod \+x|nohup )/
| eval(
vm_kill = if(CommandLine = /(vm process kill|vmsvc\/power\.off)/, 3, 0),
vib_install = if(CommandLine = /(software vib install|software vib remove|software acceptance set)/, 3, 0),
firewall_change = if(CommandLine = /network firewall/, 2, 0),
ssh_enable = if(CommandLine = /(hostsvc\/enable_ssh|hostsvc\/start_ssh)/, 2, 0),
syslog_modify = if(CommandLine = /system syslog/, 2, 0),
maintenance_mode = if(CommandLine = /system maintenanceMode/, 2, 0),
vm_enum = if(CommandLine = /(vm process list|vmsvc\/getallvms)/, 1, 0),
file_stage = if(CommandLine = /(\.vmdk|\.vmx|\.vmsd|\.vmsn|chmod \+x|nohup )/, 1, 0)
)
| eval(suspicion_score = vm_kill + vib_install + firewall_change + ssh_enable + syslog_modify + maintenance_mode + vm_enum + file_stage)
| where(suspicion_score > 0)
| groupBy(
[ComputerName, UserName, FileName, CommandLine, vm_kill, vib_install, firewall_change, ssh_enable, syslog_modify, maintenance_mode, vm_enum, file_stage, suspicion_score],
function=count(aid, as=event_count)
)
| sort(suspicion_score, order=desc)
| table([@timestamp, ComputerName, UserName, FileName, CommandLine, vm_kill, vib_install, firewall_change, ssh_enable, syslog_modify, suspicion_score, event_count])Detects ESXi hypervisor CLI abuse via Falcon sensor ProcessRollup2 events. Covers esxcli and vim-cmd invocations for VM termination (ransomware), VIB package manipulation (persistence), firewall bypass, SSH backdoor enablement, and syslog evasion. Weighted scoring model surfaces critical-severity ransomware and espionage tradecraft.
Data Sources
Required Tables
False Positives & Tuning
- CrowdStrike Falcon sensor deployment scripts or host configuration automation running esxcli commands to validate kernel module installation and sensor health on ESXi hosts
- Authorized change management activities where system administrators use esxcli bulk commands to apply security patches, VIB updates, or firewall hardening across multiple ESXi hosts during maintenance windows
- Third-party VMware integration tools and monitoring agents (Datadog, Dynatrace, Zabbix) using vim-cmd or esxcli queries to collect VM inventory, performance metrics, and host state for observability pipelines
Other platforms for T1059.012
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 1ESXi VM Enumeration Simulation
Expected signal: Syslog message with facility local7 containing 'esxcli vm process list'. This validates that ESXi-format syslog messages are being ingested by the SIEM.
- Test 2ESXi VIB Installation Simulation
Expected signal: Syslog message with facility local7 containing 'vib install' and '--no-sig-check'. The --no-sig-check flag bypasses signature verification.
- Test 3ESXi VM Kill Simulation
Expected signal: Syslog message with facility local7 containing 'vm process kill --type=force'. The force kill type is used by ransomware to immediately terminate VMs.
References (6)
- https://attack.mitre.org/techniques/T1059/012/
- https://developer.broadcom.com/xapis/esxcli-command-reference/latest/
- https://lolesxi-project.github.io/LOLESXi/
- https://www.crowdstrike.com/en-us/blog/hypervisor-jackpotting-ecrime-actors-increase-targeting-of-esxi-servers/
- https://www.mandiant.com/resources/blog/esxi-hypervisors-malware-persistence
- https://www.trendmicro.com/en_us/research/22/e/new-linux-based-ransomware-cheerscrypt-targets-exsi-devices.html
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