ESXi Administration Command

// Primary detection: Suspicious child processes spawned by VMware Tools Daemon on guest VMs
let suspiciousProcesses = dynamic(["cmd.exe", "powershell.exe", "pwsh.exe", "wscript.exe", "cscript.exe", "mshta.exe", "rundll32.exe", "regsvr32.exe", "certutil.exe", "bitsadmin.exe", "wmic.exe", "net.exe", "net1.exe", "whoami.exe", "ipconfig.exe", "nltest.exe", "ping.exe", "tasklist.exe", "netstat.exe", "schtasks.exe", "at.exe", "sc.exe", "reg.exe", "curl.exe", "wget.exe"]);
let benignChildren = dynamic(["vmtoolsd.exe", "vmwaretray.exe", "vmwareuser.exe", "VGAuthService.exe", "TPAutoConnect.exe", "vmacthlp.exe", "conhost.exe", "vmwarehostopen.exe"]);
DeviceProcessEvents
| where TimeGenerated > ago(7d)
| where InitiatingProcessFileName =~ "vmtoolsd.exe"
| where FileName !in~ (benignChildren)
| extend IsHighRisk = iff(FileName in~ (suspiciousProcesses), true, false)
| extend CommandLineLen = strlen(ProcessCommandLine)
| project
    TimeGenerated,
    DeviceName,
    AccountName,
    AccountDomain,
    FileName,
    ProcessCommandLine,
    ProcessId,
    InitiatingProcessFileName,
    InitiatingProcessCommandLine,
    InitiatingProcessParentFileName,
    InitiatingProcessParentId,
    IsHighRisk,
    FolderPath
| order by IsHighRisk desc, TimeGenerated desc

index=* (sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" OR sourcetype="WinEventLog:Security")
| eval is_sysmon=if(sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational", 1, 0)
| eval is_security=if(sourcetype="WinEventLog:Security", 1, 0)
| search (EventCode=1 AND is_sysmon=1) OR (EventCode=4688 AND is_security=1)
| eval ParentImage=coalesce(ParentImage, ParentProcessName)
| eval Image=coalesce(Image, NewProcessName)
| eval CommandLine=coalesce(CommandLine, ProcessCommandLine, CommandLine)
| where match(lower(ParentImage), "vmtoolsd\.exe$")
| eval ChildProcess=mvindex(split(Image, "\\"), -1)
| eval IsHighRisk=if(match(lower(ChildProcess), "^(cmd\.exe|powershell\.exe|pwsh\.exe|wscript\.exe|cscript\.exe|mshta\.exe|rundll32\.exe|regsvr32\.exe|certutil\.exe|bitsadmin\.exe|wmic\.exe|net\.exe|net1\.exe|whoami\.exe|nltest\.exe|schtasks\.exe|reg\.exe|curl\.exe|wget\.exe)$"), "HIGH", "MEDIUM")
| eval Hostname=coalesce(Computer, host)
| table _time, Hostname, User, ParentImage, Image, ChildProcess, CommandLine, IsHighRisk, EventCode
| sort - IsHighRisk, - _time

process where event.type == "start" and (
  process.name in~ ("powershell.exe", "cmd.exe", "wscript.exe", "cscript.exe") or
  process.parent.name in~ ("cmd.exe", "powershell.exe", "wscript.exe")
) and (
  process.command_line : ("*t1675*", "*suspicious*") or
  process.args : ("*encoded*", "*bypass*", "*hidden*")
) and not process.code_signature.trusted == true

SELECT
    DATEFORMAT(devicetime, 'yyyy-MM-dd HH:mm:ss') AS EventTime,
    LOGSOURCENAME(logsourceid) AS LogSource,
    "username" AS AccountName,
    "CommandLine" AS CommandLine,
    "ParentProcessName" AS ParentProcess,
    "NewProcessName" AS ProcessName,
    CASE
        WHEN "CommandLine" ILIKE '%powershell%' AND "CommandLine" ILIKE '%-enc%' THEN 'EncodedCommand'
        WHEN "CommandLine" ILIKE '%bypass%' THEN 'ExecutionBypass'
        WHEN "CommandLine" ILIKE '%-noprofile%' THEN 'NoProfileExecution'
        ELSE 'SuspiciousProcess'
    END AS DetectionType,
    CASE
        WHEN "username" = 'SYSTEM' THEN 70
        WHEN "CommandLine" ILIKE '%bypass%' THEN 85
        ELSE 60
    END AS RiskScore
FROM events
WHERE
    LOGSOURCETYPENAME(devicetype) IN ('Microsoft Windows Security Event Log', 'Universal DSM')
    AND eventid IN (4688, 1)
    AND ("NewProcessName" ILIKE '%powershell.exe%'
        OR "NewProcessName" ILIKE '%cmd.exe%'
        OR "NewProcessName" ILIKE '%wscript.exe%'
        OR "NewProcessName" ILIKE '%cscript.exe%'
        OR "NewProcessName" ILIKE '%mshta.exe%')
    AND RiskScore >= 60
ORDER BY EventTime DESC
LAST 1 HOURS

_sourceCategory=windows/sysmon EventCode=1
| json auto
| where process_name in ("powershell.exe", "cmd.exe", "wscript.exe", "cscript.exe", "mshta.exe", "rundll32.exe")
| where process_cmdline matches /(-enc|-encodedcommand|-bypass|-hidden|invoke-expression|iex\s)/i
    OR process_cmdline matches /(http:\/\/|https:\/\/|ftp:\/\/)/i
| if(process_cmdline matches /-enc/i, "EncodedCommand",
    if(process_cmdline matches /-bypass/i, "BypassExecution",
    if(process_cmdline matches /(invoke-expression|iex)/i, "ScriptExecution",
    "SuspiciousProcess"))) as detection_type
| if(parent_process_name in ("w3wp.exe","httpd.exe","nginx.exe"), 95,
    if(process_cmdline matches /-enc/i, 85,
    if(process_cmdline matches /-bypass/i, 75, 60))) as risk_score
| where risk_score >= 60
| count by host, user, process_name, process_cmdline, parent_process_name, detection_type, risk_score
| sort - risk_score

rule detection_t1675 {
  meta:
    author = "Argus Detection Platform"
    description = "Detects ESXi Administration Command - T1675"
    severity = "HIGH"
    mitre_attack = "T1675"
    reference = "https://attack.mitre.org/techniques/T1675/"

  events:
    $e.metadata.event_type = "PROCESS_LAUNCH"
    $e.principal.hostname = $hostname
    $e.target.process.file.full_path = $process_path
    $e.target.process.command_line = $cmdline
    (
      re.regex($e.target.process.file.full_path, `(?i)(powershell|cmd|wscript|cscript|mshta|rundll32)\.exe$`) and
      (
        re.regex($e.target.process.command_line, `(?i)-enc(odedcommand)?`) or
        re.regex($e.target.process.command_line, `(?i)-bypass`) or
        re.regex($e.target.process.command_line, `(?i)(invoke-expression|iex\s)`) or
        re.regex($e.target.process.command_line, `(?i)http://`)
      )
    )
    not re.regex($e.principal.process.file.full_path, `(?i)(trustedinstaller|msiexec|svchost)`)

  condition:
    $e
}

#event_simpleName = "ProcessRollup2"
| ImageFileName = /(?i)(powershell|cmd|wscript|cscript|mshta|rundll32)\.exe$/
| CommandLine = /(?i)(-enc(odedcommand)?|-bypass|-noprofile|invoke-expression|iex\s|http:\/\/)/
| case {
    CommandLine = /(?i)-enc(odedcommand)?/ | DetectionType := "EncodedCommand" ;
    CommandLine = /(?i)-bypass/ | DetectionType := "BypassExecution" ;
    CommandLine = /(?i)(invoke-expression|iex\s)/ | DetectionType := "ScriptExecution" ;
    * | DetectionType := "SuspiciousProcess"
}
| case {
    ParentBaseFileName = /(?i)(w3wp|httpd|nginx|php-cgi)\.exe/ | RiskScore := "Critical" ;
    CommandLine = /(?i)-enc/ | RiskScore := "High" ;
    * | RiskScore := "Medium"
}
| table([ComputerName, UserName, ImageFileName, CommandLine, ParentBaseFileName, DetectionType, RiskScore, ProcessId, ParentProcessId])
| sort(RiskScore, order=desc, limit=100)