Rare RDP Connections

Severity: medium
Time window: 14d
Group by: Account, AccountType, Activity, Computer, IpAddress, LogonTypeName, ProcessName
Author: Microsoft Security Research
Source: github.com/Azure/Azure-Sentinel

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

MITRE ATT&CK coverage

Tactic	Techniques
Lateral Movement	`T1021` Remote Services

Event coverage

Provider	Event	Title
Security-Auditing	Event ID 4624	An account was successfully logged on.

Rule body kusto

id: 45b903c5-6f56-4969-af10-ae62ac709718
name: Rare RDP Connections
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'
severity: Medium
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsForwardedEvents
    dataTypes:
      - WindowsEvent
queryFrequency: 1d
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - LateralMovement
relevantTechniques:
  - T1021
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
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: Account
      - identifier: Name
        columnName: AccountName
      - identifier: NTDomain
        columnName: AccountNTDomain
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
      - identifier: HostName
        columnName: HostName
      - identifier: NTDomain
        columnName: HostNameDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IpAddress
version: 1.2.5
kind: Scheduled
metadata:
    source:
        kind: Community
    author:
        name: Microsoft Security Research
    support:
        tier: Community
    categories:
        domains: [ "Security - Threat Protection" ]

Stages and Predicates

Parameters

let starttime = 14d;
let endtime = 1d;

union `isfuzzy=true` (2 sources)

Each leg below queries one source; the rule matches if any leg does. Sources: SecurityEvent, WindowsEvent

Leg 1: `SecurityEvent`

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

Leg 2: `WindowsEvent`

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

Applied to the combined result

| 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

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`EventID`	eq	`4624`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`EventData`	match	`10` transforms: `term` corpus 3 (kusto 3)
`EventID`	eq	`4624` transforms: `cased` corpus 25 (splunk 13, kusto 8, chronicle 4)
`LogonType`	eq	`10` transforms: `cased` corpus 8 (kusto 4, sigma 3, splunk 1)

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field	Source
`Account`	`summarize`
`AccountType`	`summarize`
`Activity`	`summarize`
`Computer`	`summarize`
`ConnectionCount`	`summarize`
`EndTime`	`summarize`
`IpAddress`	`summarize`
`LogonTypeName`	`summarize`
`ProcessName`	`summarize`
`StartTime`	`summarize`
`HostName`	`extend`
`HostNameDomain`	`extend`
`AccountNTDomain`	`extend`
`AccountName`	`extend`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Rare RDP Connections

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

union `isfuzzy=true` (2 sources)

Leg 1: `SecurityEvent`

Leg 2: `WindowsEvent`

Applied to the combined result

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Rare RDP Connections

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

union isfuzzy=true (2 sources)

Leg 1: SecurityEvent

Leg 2: WindowsEvent

Applied to the combined result

Exclusions

Indicators

Output fields

union `isfuzzy=true` (2 sources)

Leg 1: `SecurityEvent`

Leg 2: `WindowsEvent`