Detection rules › Kusto

Potential Kerberos Relaying Activity - MDE

Time window
20s
Group by
DeviceId, DeviceName
Author
Cyb3rMonk
Source
github.com/Cyb3r-Monk/Threat-Hunting-and-Detection

The below query detects potential Kerberos relaying event chain generated by KrbRelay.

MITRE ATT&CK coverage

TacticTechniques
Credential AccessNo specific technique

References

Event coverage

Rule body kusto

// Author       : Cyb3rMonk(https://twitter.com/Cyb3rMonk, https://mergene.medium.com)
//
// Link to original post:
// https://posts.bluraven.io/detecting-kerberos-relaying-e6be66fa647c
//
// Description: This query detects potential Kerberos relaying event chain generated by KrbRelay(https://github.com/cube0x0/KrbRelay).
//
// Query parameters:
//
union DeviceProcessEvents, DeviceEvents, DeviceNetworkEvents
| where Timestamp > ago(60m)
| extend PipeName_ = tostring(todynamic(AdditionalFields).PipeName)
| extend Action = case(
    (ActionType=="ConnectionSuccess" and RemotePort in (389, 636)), 'ConnectToDC', 
    (ActionType=="ListeningConnectionCreated"), 'ListeningConnectionCreated', 
    (ActionType=="NamedPipeEvent" and PipeName_ has @"Winsock2\CatalogChangeListener"), 'NamedPipeEvent',
    (ActionType=="ProcessCreated" and InitiatingProcessCommandLine == "svchost.exe -k DcomLaunch -p"), 'DcomProcessCreated',
    (ActionType=="ConnectionSuccess" and LocalIP==RemoteIP and InitiatingProcessParentFileName=="svchost.exe"), 'DcomProcessConnecToSelf', 'Other'
    )
| summarize Actions = make_set_if(Action, Action <> "Other") by DeviceId, DeviceName, bin(Timestamp,20s)
| where array_length(Actions)==5
| project-rename ActivityTimestamp = Timestamp
| join kind=inner (
    DeviceProcessEvents
    | where Timestamp > ago(60m)
    | where ActionType=="ProcessCreated" and InitiatingProcessCommandLine == "svchost.exe -k DcomLaunch -p"
    ) on DeviceId
    | where abs(datetime_diff('second', Timestamp, ActivityTimestamp)) <=20

union DeviceProcessEvents, DeviceEvents, DeviceNetworkEvents
| where Timestamp > ago(60m)
| extend PipeName_ = tostring(todynamic(AdditionalFields).PipeName)
| where 
    (ActionType=="ConnectionSuccess" and RemotePort in (389, 636)) or 
    (ActionType=="ListeningConnectionCreated") or 
    (ActionType=="NamedPipeEvent" and PipeName_ has @"Winsock2\CatalogChangeListener") or
    (ActionType=="ProcessCreated" and InitiatingProcessCommandLine == "svchost.exe -k DcomLaunch -p") or
    (ActionType=="ConnectionSuccess" and LocalIP==RemoteIP and InitiatingProcessParentFileName=="svchost.exe")
    | sort by Timestamp desc

Stages and Predicates

union (3 sources)

Each leg below queries one source; the rule matches if any leg does. Sources: DeviceProcessEvents, DeviceEvents, DeviceNetworkEvents

Leg 1: DeviceProcessEvents

Leg 2: DeviceEvents

Leg 3: DeviceNetworkEvents

Applied to the combined result

| where Timestamp > ago(60m) | extend PipeName_ = tostring(todynamic(AdditionalFields).PipeName) | extend Action = case(
    (ActionType=="ConnectionSuccess" and RemotePort in (389, 636)), 'ConnectToDC', 
    (ActionType=="ListeningConnectionCreated"), 'ListeningConnectionCreated', 
    (ActionType=="NamedPipeEvent" and PipeName_ has @"Winsock2\CatalogChangeListener"), 'NamedPipeEvent',
    (ActionType=="ProcessCreated" and InitiatingProcessCommandLine == "svchost.exe -k DcomLaunch -p"), 'DcomProcessCreated',
    (ActionType=="ConnectionSuccess" and LocalIP==RemoteIP and InitiatingProcessParentFileName=="svchost.exe"), 'DcomProcessConnecToSelf', 'Other'
    ) | summarize Actions = make_set_if(Action, Action <> "Other") by DeviceId, DeviceName, bin(Timestamp,20s) | where array_length(Actions)==5 | project-rename ActivityTimestamp = Timestamp | join kind=inner (
    DeviceProcessEvents
    | where Timestamp > ago(60m)
    | where ActionType=="ProcessCreated" and InitiatingProcessCommandLine == "svchost.exe -k DcomLaunch -p"
    ) on DeviceId | where abs(datetime_diff('second', Timestamp, ActivityTimestamp)) <=20

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.

FieldKindValues
ActionTypeeq
  • ProcessCreated transforms: cased corpus 10 (kusto 10)
Actionseq
  • 5 transforms: array_length
InitiatingProcessCommandLineeq
  • svchost.exe -k DcomLaunch -p transforms: cased

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.

FieldSource
Actionssummarize
DeviceIdsummarize
DeviceNamesummarize
ActivityTimestampproject-rename