Detections/SecurityEvent/RDP_MultipleConnectionsFromSingleSystem.yaml

id: 78422ef2-62bf-48ca-9bab-72c69818a425
name: Multiple RDP connections from Single System
description: |
  'Identifies when an RDP connection is made to multiple systems and above the normal connection count for the previous 7 days.
  Connections from the same system with the same account within the same day.
  RDP connections are indicated by the EventID 4624 with LogonType = 10'
severity: Low
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsForwardedEvents
    dataTypes:
      - WindowsEvent
queryFrequency: 1d
queryPeriod: 8d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - LateralMovement
relevantTechniques:
  - T1021
query: |
  let endtime = 1d;
  let starttime = 8d;
  let threshold = 2.0;
  (union isfuzzy=true
  (SecurityEvent
  | where TimeGenerated >= ago(endtime)
  | where EventID == 4624 and LogonType == 10
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), ComputerCountToday = dcount(Computer), ComputerSet = makeset(Computer), ProcessSet = makeset(ProcessName)
  by Account = tolower(Account), IpAddress, AccountType, Activity, LogonTypeName),
  (WindowsEvent
  | where TimeGenerated >= ago(endtime)
  | where EventID == 4624
  | extend LogonType = tostring(EventData.LogonType)
  | where  LogonType == 10
  | extend ProcessName = tostring(EventData.ProcessName)
  | extend Account = strcat(tostring(EventData.TargetDomainName),"\\", tostring(EventData.TargetUserName))
  | extend IpAddress = tostring(EventData.IpAddress)
  | extend TargetUserSid = tostring(EventData.TargetUserSid)
  | extend AccountType=case(Account endswith "$" or TargetUserSid in ("S-1-5-18", "S-1-5-19", "S-1-5-20"), "Machine", isempty(TargetUserSid), "", "User")
  | extend Activity="4624 - An account was successfully logged on."
  | extend LogonTypeName="10 - RemoteInteractive"
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), ComputerCountToday = dcount(Computer), ComputerSet = makeset(Computer), ProcessSet = makeset(ProcessName)
  by Account = tolower(Account), IpAddress, AccountType, Activity, LogonTypeName)
  )
  | join kind=inner (
  (union isfuzzy=true
  (SecurityEvent
  | where TimeGenerated >= ago(starttime) and TimeGenerated < ago(endtime)
  | where EventID == 4624 and LogonType == 10
  | summarize ComputerCountPrev7Days = dcount(Computer) by Account = tolower(Account), IpAddress
  ),
  ( WindowsEvent
  | where TimeGenerated >= ago(starttime) and TimeGenerated < ago(endtime)
  | where EventID == 4624  and EventData has ("10")
  | extend LogonType = toint(EventData.LogonType)
  | where  LogonType == 10
  | extend Account = strcat(tostring(EventData.TargetDomainName),"\\", tostring(EventData.TargetUserName))
  | extend IpAddress = tostring(EventData.IpAddress)
  | summarize ComputerCountPrev7Days = dcount(Computer) by Account = tolower(Account), IpAddress)
  )
  ) on Account, IpAddress
  | extend Ratio = iff(isempty(ComputerCountPrev7Days), toreal(ComputerCountToday), ComputerCountToday / (ComputerCountPrev7Days * 1.0))
  // Where the ratio of today to previous 7 days is more than double.
  | where Ratio > threshold
  | project StartTime, EndTime, Account, IpAddress, ComputerSet, ComputerCountToday, ComputerCountPrev7Days, Ratio, AccountType, Activity, LogonTypeName, ProcessSet
  | extend AccountName = tostring(split(Account, @"\")[1]), AccountNTDomain = tostring(split(Account, @"\")[0])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: Account
      - identifier: Name
        columnName: AccountName
      - identifier: NTDomain
        columnName: AccountNTDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IpAddress
version: 1.2.6
kind: Scheduled
metadata:
    source:
        kind: Community
    author:
        name: Microsoft Security Research
    support:
        tier: Community
    categories:
        domains: [ "Security - Threat Protection" ]