Content Injection

let LookbackTime = 1d;
let UpdateDomains = dynamic(["windowsupdate.com", "update.microsoft.com", "download.microsoft.com", "delivery.mp.microsoft.com"]);
let SuspiciousChildren = dynamic(["wscript.exe", "cscript.exe", "mshta.exe", "rundll32.exe", "regsvr32.exe", "certutil.exe", "bitsadmin.exe", "msiexec.exe", "powershell.exe", "cmd.exe"]);
let InjectionParents = dynamic(["svchost.exe", "wuauclt.exe", "usoclient.exe", "chrome.exe", "firefox.exe", "msedge.exe", "iexplore.exe"]);
let HttpUpdateConnections = DeviceNetworkEvents
| where TimeGenerated > ago(LookbackTime)
| where RemotePort == 80
| where RemoteUrl has_any (UpdateDomains)
| project DeviceId, DeviceName, NetworkTime = TimeGenerated, RemoteIP, RemoteUrl;
let SuspiciousSpawns = DeviceProcessEvents
| where TimeGenerated > ago(LookbackTime)
| where InitiatingProcessFileName in~ (InjectionParents)
| where FileName in~ (SuspiciousChildren)
| where ProcessCommandLine has_any ("http://", "invoke-webrequest", "wget", "curl", "-enc ", "download", "bitsadmin")
    or FolderPath has "temp" or FolderPath has "downloads"
| project DeviceId, DeviceName, ProcessTime = TimeGenerated, FileName, FolderPath, ProcessCommandLine, InitiatingProcessFileName, InitiatingProcessCommandLine, AccountName, SHA256;
HttpUpdateConnections
| join kind=inner SuspiciousSpawns on DeviceId
| where abs(datetime_diff('second', NetworkTime, ProcessTime)) <= 300
| project NetworkTime, ProcessTime, DeviceName, AccountName, RemoteIP, RemoteUrl, SuspiciousProcess = FileName, SuspiciousProcessPath = FolderPath, ProcessCommandLine, ParentProcess = InitiatingProcessFileName, ParentCommandLine = InitiatingProcessCommandLine, SHA256, TimeDeltaSec = abs(datetime_diff('second', NetworkTime, ProcessTime))
| order by NetworkTime desc

index=* sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=1
| eval process=lower(Image)
| eval parent=lower(ParentImage)
| eval cmdline=lower(CommandLine)
| eval workdir=lower(CurrentDirectory)
| where match(parent, "svchost\.exe|wuauclt\.exe|usoclient\.exe|chrome\.exe|firefox\.exe|msedge\.exe|iexplore\.exe")
| where match(process, "wscript\.exe|cscript\.exe|mshta\.exe|rundll32\.exe|regsvr32\.exe|certutil\.exe|bitsadmin\.exe|msiexec\.exe|powershell\.exe|cmd\.exe")
| where match(cmdline, "http://|ftp://|invoke-webrequest|wget |curl |bitsadmin|/transfer")
    OR match(cmdline, "-enc |-encodedcommand ")
    OR like(workdir, "%temp%") OR like(workdir, "%downloads%")
| eval risk_score=case(
    match(parent, "svchost\.exe|wuauclt\.exe|usoclient\.exe") AND match(cmdline, "http://"), 95,
    match(cmdline, "-enc |-encodedcommand "), 90,
    match(parent, "chrome\.exe|firefox\.exe|msedge\.exe|iexplore\.exe") AND match(process, "powershell\.exe|cmd\.exe"), 85,
    like(workdir, "%temp%") OR like(workdir, "%downloads%"), 75,
    true(), 65
)
| table _time, host, User, process, parent, cmdline, workdir, Hashes, risk_score
| sort -risk_score, -_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 : ("*t1659*", "*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_t1659 {
  meta:
    author = "Argus Detection Platform"
    description = "Detects Content Injection - T1659"
    severity = "HIGH"
    mitre_attack = "T1659"
    reference = "https://attack.mitre.org/techniques/T1659/"

  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)