Multiple Domainentity Cisco Umbrella Dns Cl
KQL detection rule by ep3p · MIT
This query assumes a feed of threat indicators is ingested/synchronized periodically, and each synchronization ingests new indicators and only old indicators that have been modified. Active threat indicators in Sentinel are renovated as ThreatIntelligenceIndicator events every ~12 days.
// This query assumes a feed of threat indicators is ingested/synchronized periodically, and each synchronization ingests new indicators and only old indicators that have been modified.
// Active threat indicators in Sentinel are renovated as ThreatIntelligenceIndicator events every ~12 days.
let query_frequency = 1h;
let query_period = 14d;
let query_wait = 0h;
let table_query_lookback = 12h;
let _TIBenignProperty =
_GetWatchlist('ID-TIBenignProperty')
| where Notes has_any ("[DestinationDomain]")
| project IndicatorId, BenignProperty
;
let _TIExcludedSources = toscalar(
_GetWatchlist('Activity-ExpectedSignificantActivity')
| where Activity == "ThreatIndicatorSource"
| summarize make_list(Auxiliar)
);
let _TITableMatch = (table_start: datetime, table_end: datetime, only_new_ti: boolean, ti_start: datetime = datetime(null)) {
// Scheduled Analytics rules have a query period limit of 14d
let _Indicators =// materialize(
ThreatIntelligenceIndicator
| where TimeGenerated > ago(query_period)
// Take the earliest TimeGenerated and the latest column info
| summarize hint.strategy=shuffle
minTimeGenerated = min(TimeGenerated),
arg_max(TimeGenerated, Active, Description, ActivityGroupNames, IndicatorId, ThreatType, DomainName, Url, ExpirationDateTime, ConfidenceScore, AdditionalInformation, ExternalIndicatorId)
by IndicatorId
// Remove inactive or expired indicators
| where not(not(Active) or ExpirationDateTime < now())
// Pick indicators that contain the desired entity type
| where isnotempty(DomainName)
| extend Domain = tolower(DomainName)
// Remove indicators from specific sources
| where not(AdditionalInformation has_any (_TIExcludedSources) or Description has_any (_TIExcludedSources))
// Remove excluded indicators with benign properties
| join kind=leftanti _TIBenignProperty on IndicatorId, $left.Domain == $right.BenignProperty
// Deduplicate indicators by Domain column, equivalent to using join kind=innerunique afterwards
| summarize hint.strategy=shuffle
minTimeGenerated = min(minTimeGenerated),
take_any(*)
by Domain
// If we want only new indicators, remove indicators received previously
| where not(only_new_ti and minTimeGenerated < ti_start)
//)
;
//let _IndicatorsLength = toscalar(_Indicators | summarize count());
//let _IndicatorsPrefilter = toscalar(
// _Indicators
// | extend AuxiliarField = tostring(split(Domain, ".")[-1])
// | summarize make_set_if(AuxiliarField, isnotempty(AuxiliarField))
//);
//let _IndicatorsPrefilterLength = array_length(_IndicatorsPrefilter);
let _TableEvents =
Cisco_Umbrella_dns_CL
| where TimeGenerated between (table_start .. table_end)
// Filter events that may contain indicators
| where isnotempty(Domain_s)
//| where not(_IndicatorsPrefilterLength < 10000 and not(Domain_s has_any (_IndicatorsPrefilter))) // valid TLD ~1500 , "has_any" limit 10000
| summarize hint.strategy=shuffle take_any(*) by OriginalDomain = trim_end(@"\.", tolower(Domain_s))
//| where not(_IndicatorsPrefilterLength < 10000 and not(tostring(split(OriginalDomain, ".")[-1]) in (_IndicatorsPrefilter)))
| extend SplitLevelDomains = split(OriginalDomain, ".")
| mv-expand Level = range(0, array_length(SplitLevelDomains) - 2) to typeof(int)
| extend Domain = strcat_array(array_slice(SplitLevelDomains, Level, -1), ".")
//| where not(_IndicatorsLength < 1000000 and not(Domain in (toscalar(_Indicators | summarize make_list(Domain))))) // "in" limit 1.000.000
| project-rename Cisco_Umbrella_dns_CL_TimeGenerated = TimeGenerated
;
_Indicators
| join kind=inner hint.strategy=shuffle _TableEvents on Domain
// Take only a single event by key columns
//| summarize hint.strategy=shuffle take_any(*) by Domain, Identities
| project
Cisco_Umbrella_dns_CL_TimeGenerated,
Description, ActivityGroupNames, IndicatorId, ThreatType, DomainName, Url, ExpirationDateTime, ConfidenceScore, AdditionalInformation,
EventStartTime = todatetime(column_ifexists('Timestamp_t', column_ifexists('Timestamp_s', ''))),
Dvc = "CiscoUmbrella",
DvcAction = column_ifexists('Action_s', ''),
QueryType_s,
SrcIpAddr = column_ifexists('InternalIp_s', ''),
SrcNatIpAddr = column_ifexists('ExternalIp_s', ''),
DnsQuery = trim_end(@'\.', column_ifexists('Domain_s', '')),
EventResult = iff(ResponseCode_s =~ 'NOERROR', 'Success', 'Failure'),
EventResultDetails = ResponseCode_s, // => ResponseCodeNames
UrlCategory = column_ifexists('Categories_s', ''),
ThreatCategory = column_ifexists('Blocked_Categories_s', ''),
IdentityTypes = column_ifexists('Identity_Types_s', ''),
Identities = column_ifexists('Identities_s', ''),
PolicyIdentityType = column_ifexists('Policy_Identity_Type_s', ''),
PolicyIdentity = column_ifexists('Policy_Identity_s', '')
| mv-apply
Identities_s_aux = todynamic(Identities) to typeof(string),
Identity_Types_s_aux = todynamic(IdentityTypes) to typeof(string) on (
summarize IdentitiesDict = make_bag(pack(Identity_Types_s_aux, Identities_s_aux))
)
| extend
HostName = tostring(IdentitiesDict["AD Computers"]),
UserPrincipalName = tostring(IdentitiesDict["AD Users"])
| parse QueryType_s with DnsQueryType: int " (" DnsQueryTypeName: string ")"
| project-away QueryType_s, IdentitiesDict
};
union// isfuzzy=true
// Match current table events all indicators available
_TITableMatch(ago(query_frequency + query_wait), ago(query_wait), false),
// Match past table events new indicators since last query execution
_TITableMatch(ago(table_query_lookback + query_wait), ago(query_frequency + query_wait), true, ago(query_frequency))
| summarize arg_max(Cisco_Umbrella_dns_CL_TimeGenerated, *) by IndicatorId, Identities
| extend
timestamp = Cisco_Umbrella_dns_CL_TimeGenerated,
HostCustomEntity = HostName,
AccountCustomEntity = UserPrincipalName,
URLCustomEntity = Url