Detect vSphere Installation Bundles in CrowdStrike LogScale
Adversaries abuse VMware vSphere Installation Bundles (VIBs) to achieve persistent access on ESXi hypervisors. VIBs are software packages that persist across reboots by being incorporated into the ESXi boot image. Malicious VIBs can deploy backdoors, custom firewall rules, and startup scripts. UNC3886 used malicious VIBs to install VIRTUALPIE backdoor on ESXi. VIBs can be installed with --force flag to bypass acceptance level requirements, and adversaries masquerade them as PartnerSupported by modifying the XML descriptor. ESXi detection is challenging due to limited logging.
MITRE ATT&CK
- Tactic
- Persistence
- Technique
- T1505 Server Software Component
- Sub-technique
- T1505.006 vSphere Installation Bundles
- Canonical reference
- https://attack.mitre.org/techniques/T1505/006/
LogScale Detection Query
// Part 1: Detect esxcli, PowerCLI binary execution or VIB-related command lines
#event_simpleName = ProcessRollup2
| FileName = /(?i)(esxcli|esxcfg-dumppart|powercli|vmwarecli)\.exe/
OR CommandLine = /(?i)(software\s+vib\s+install|--vibs|esxcli\s+software)/
OR (
FileName = /(?i)(powershell|pwsh)\.exe/
AND CommandLine = /(?i)(Install-EsxSoftwarePackage|Add-EsxSoftwareDepot|Get-EsxSoftwarePackage|esxcli\.software\.vib|esxupdate)/
AND CommandLine = /(?i)(vib|esxi|vmware|vsphere)/
)
| eval DetectionType = case(
FileName matches /(?i)(esxcli|esxcfg-dumppart|powercli|vmwarecli)\.exe/,
"VIB_CLI_Execution",
CommandLine matches /(?i)(software\s+vib\s+install|--vibs|esxcli\s+software)/,
"VIB_Install_Command",
FileName matches /(?i)(powershell|pwsh)\.exe/ AND CommandLine matches /(?i)(Install-EsxSoftwarePackage|Add-EsxSoftwareDepot|esxcli\.software\.vib)/,
"VIB_PowerCLI_Cmdlet",
true(), "VIB_Generic_Match"
)
| table([@timestamp, ComputerName, UserName, FileName, CommandLine, ParentBaseFileName, DetectionType])
| sort(field=@timestamp, order=desc)
// Part 2: Detect .vib or .vgz file writes
// #event_simpleName = PeFileWritten OR #event_simpleName = NewExecutableWritten
// | TargetFileName = /(?i)\.(vib|vgz)$/
// | "VIB_File_Drop" as DetectionType
// | table([@timestamp, ComputerName, UserName, TargetFileName, FileName, CommandLine, DetectionType])
// Combined groupBy for summary view:
// groupBy([ComputerName, DetectionType], function=[count(as=EventCount), collect([UserName, FileName, CommandLine])])
// | sort(field=EventCount, order=desc)CrowdStrike LogScale (Falcon) query detecting vSphere VIB installation activity on Windows management hosts. Monitors ProcessRollup2 events for esxcli/PowerCLI binary execution and PowerShell invocations of VIB management cmdlets. Companion query (commented) covers PeFileWritten/NewExecutableWritten events for .vib/.vgz package drops. Requires Falcon sensor on Windows vSphere management hosts.
Data Sources
Required Tables
False Positives & Tuning
- vCenter Server Appliance (VCSA) internal processes and vSphere Update Manager (VUM) baseline scans generating esxcli process telemetry on Windows vCenter clients
- PowerCLI-based automation used by cloud management platforms (Tanzu, vRealize Automation) for routine ESXi lifecycle operations such as cluster expansion
- Incident response or forensic tools such as VMware Live Recovery or third-party IR platforms that enumerate or extract VIB inventory from ESXi hosts during investigations
Other platforms for T1505.006
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 1List Installed VIBs on ESXi Host
Expected signal: ESXi shell audit log: esxcli command execution. If ESXi syslog is forwarded: syslog entry for esxcli invocation.
- Test 2Check ESXi VIB Acceptance Level
Expected signal: ESXi shell audit log for esxcli execution.
- Test 3Simulate VIB Install CLI Command on Windows Management Host
Expected signal: Sysmon EventCode 1: powershell.exe with CommandLine containing 'vib install' and '--force'.
References (4)
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