Rare RDP Connections

let starttime = 14d;
let endtime = 1d;
(union isfuzzy=true
(SecurityEvent
| where TimeGenerated >= ago(endtime)
| where EventID == 4624 and LogonType == 10
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), ConnectionCount = count()
by Account = tolower(Account), Computer = toupper(Computer), IpAddress, AccountType, Activity, LogonTypeName, ProcessName
// use left anti to exclude anything from the previous 14 days that is not rare
),
(WindowsEvent
| where TimeGenerated >= ago(endtime)
| where EventID == 4624 and EventData has ("10")
| extend LogonType = tostring(EventData.LogonType)
| where  LogonType == 10
| extend Account = strcat(tostring(EventData.TargetDomainName),"\\", tostring(EventData.TargetUserName))
| extend ProcessName = tostring(EventData.ProcessName)
| 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), ConnectionCount = count()
by Account = tolower(Account), Computer = toupper(Computer), IpAddress, AccountType, Activity, LogonTypeName, ProcessName
))
| join kind=leftanti (
(union isfuzzy=true
(SecurityEvent
| where TimeGenerated between (ago(starttime) .. ago(endtime))
| where EventID == 4624
| summarize by Computer = toupper(Computer), IpAddress, Account = tolower(Account)
),
( WindowsEvent
| where TimeGenerated between (ago(starttime) .. ago(endtime))
| where EventID == 4624
| extend IpAddress = tostring(EventData.IpAddress)
| extend Account = strcat(tostring(EventData.TargetDomainName),"\\", tostring(EventData.TargetUserName))
| summarize by Computer = toupper(Computer), IpAddress, Account = tolower(Account)
))
) on Account, Computer
| summarize StartTime = min(StartTime), EndTime = max(EndTime), ConnectionCount = sum(ConnectionCount)
by Account, Computer, IpAddress, AccountType, Activity, LogonTypeName, ProcessName
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend AccountName = tostring(split(Account, @"\")[1]), AccountNTDomain = tostring(split(Account, @"\")[0])
| project-away DomainIndex

description: |
  'Identifies when an RDP connection is new or rare related to any logon type by a given account today compared with the previous 14 days.
  RDP connections are indicated by the EventID 4624 with LogonType = 10'  
kind: Scheduled
tactics:
- LateralMovement
requiredDataConnectors:
- connectorId: SecurityEvents
  dataTypes:
  - SecurityEvent
- connectorId: WindowsSecurityEvents
  dataTypes:
  - SecurityEvent
- connectorId: WindowsForwardedEvents
  dataTypes:
  - WindowsEvent
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/RDP_RareConnection.yaml
severity: Medium
name: Rare RDP Connections
metadata:
  support:
    tier: Community
  author:
    name: Microsoft Security Research
  categories:
    domains:
    - Security - Threat Protection
  source:
    kind: Community
triggerThreshold: 0
queryPeriod: 14d
query: |
  let starttime = 14d;
  let endtime = 1d;
  (union isfuzzy=true
  (SecurityEvent
  | where TimeGenerated >= ago(endtime)
  | where EventID == 4624 and LogonType == 10
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), ConnectionCount = count()
  by Account = tolower(Account), Computer = toupper(Computer), IpAddress, AccountType, Activity, LogonTypeName, ProcessName
  // use left anti to exclude anything from the previous 14 days that is not rare
  ),
  (WindowsEvent
  | where TimeGenerated >= ago(endtime)
  | where EventID == 4624 and EventData has ("10")
  | extend LogonType = tostring(EventData.LogonType)
  | where  LogonType == 10
  | extend Account = strcat(tostring(EventData.TargetDomainName),"\\", tostring(EventData.TargetUserName))
  | extend ProcessName = tostring(EventData.ProcessName)
  | 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), ConnectionCount = count()
  by Account = tolower(Account), Computer = toupper(Computer), IpAddress, AccountType, Activity, LogonTypeName, ProcessName
  ))
  | join kind=leftanti (
  (union isfuzzy=true
  (SecurityEvent
  | where TimeGenerated between (ago(starttime) .. ago(endtime))
  | where EventID == 4624
  | summarize by Computer = toupper(Computer), IpAddress, Account = tolower(Account)
  ),
  ( WindowsEvent
  | where TimeGenerated between (ago(starttime) .. ago(endtime))
  | where EventID == 4624
  | extend IpAddress = tostring(EventData.IpAddress)
  | extend Account = strcat(tostring(EventData.TargetDomainName),"\\", tostring(EventData.TargetUserName))
  | summarize by Computer = toupper(Computer), IpAddress, Account = tolower(Account)
  ))
  ) on Account, Computer
  | summarize StartTime = min(StartTime), EndTime = max(EndTime), ConnectionCount = sum(ConnectionCount)
  by Account, Computer, IpAddress, AccountType, Activity, LogonTypeName, ProcessName
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
  | extend AccountName = tostring(split(Account, @"\")[1]), AccountNTDomain = tostring(split(Account, @"\")[0])
  | project-away DomainIndex  
relevantTechniques:
- T1021
id: 45b903c5-6f56-4969-af10-ae62ac709718
queryFrequency: 1d
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: Account
    identifier: FullName
  - columnName: AccountName
    identifier: Name
  - columnName: AccountNTDomain
    identifier: NTDomain
- entityType: Host
  fieldMappings:
  - columnName: Computer
    identifier: FullName
  - columnName: HostName
    identifier: HostName
  - columnName: HostNameDomain
    identifier: NTDomain
- entityType: IP
  fieldMappings:
  - columnName: IpAddress
    identifier: Address
triggerOperator: gt
version: 1.2.5