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Potential DGA(Domain Generation Algorithm) detected via Repetitive Failures - Anomaly based (ASIM DNS Solution)
Description
'This rule makes use of the series decompose anomaly method to detect clients with a high NXDomain response count, which could be indicative of a DGA (cycling through possible C2 domains where most C2s are not live). An alert is generated when new IP address DNS activity is identified as an outlier when compared to the baseline, indicating a recurring pattern. It utilizes [ASIM](https://aka.ms/AboutASIM) normalization and is applied to any source that supports the ASIM DNS schema. The rule also depends on the "**DNSEssentialsCustomParser**" Parser, so please make sure it is installed and configured before you use this Rule.'
- Rule type
- Scheduled
- Version
- 1.0.3
- Declared status
- Available
- Query frequency
- 1d
- Query period
- 14d
- Trigger
- gt 0
Declared MITRE coverage
KQL query
Original query, unchanged.
let threshold = 2.5;
let min_t = ago(14d);
let max_t = now();
let timeframe = 1d;
// calculate avg. eps(events per second)
let eps = materialize (_Im_Dns
| project TimeGenerated
| where TimeGenerated > ago(5m)
| count
| extend Count = Count / 300);
let maxSummarizedTime = toscalar (
union isfuzzy=true
(
DNSEssentialsCustomParser
| where Type in ("DNS_Summarized_Logs_ip_CL", "DNS_Summarized_Logs_ipV1_CL")
| where EventTime_t >= min_t
| summarize max_TimeGenerated=max(EventTime_t)
| extend max_TimeGenerated = datetime_add('hour', 1, max_TimeGenerated)
),
(
print(min_t)
| project max_TimeGenerated = print_0
)
| summarize maxTimeGenerated = max(max_TimeGenerated)
);
let summarizationexist = materialize(
union isfuzzy=true
(
DNSEssentialsCustomParser
| where Type in ("DNS_Summarized_Logs_ip_CL", "DNS_Summarized_Logs_ipV1_CL")
| where EventTime_t > ago(1d)
| project v = int(2)
),
(
print int(1)
| project v = print_0
)
| summarize maxv = max(v)
| extend sumexist = (maxv > 1)
);
let allData = union isfuzzy=true
(
(datatable(exists: int, sumexist: bool)[1, false]
| where toscalar(eps) > 1000
| join (summarizationexist) on sumexist)
| join (
_Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(2d)), endtime=now())
| where TimeGenerated > maxSummarizedTime
| summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
| extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
)
on exists
| project-away exists, maxv, sum*
),
(
(datatable(exists: int, sumexist: bool)[1, false]
| where toscalar(eps) between (501 .. 1000)
| join (summarizationexist) on sumexist)
| join (
_Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(3d)), endtime=now())
| where TimeGenerated > maxSummarizedTime
| summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
| extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
)
on exists
| project-away exists, maxv, sum*
),
(
(datatable(exists: int, sumexist: bool)[1, false]
| where toscalar(eps) <= 500
| join (summarizationexist) on sumexist)
| join (
_Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(4d)), endtime=now())
| where TimeGenerated > maxSummarizedTime
| summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
| extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
)
on exists
| project-away exists, maxv, sum*
),
(
DNSEssentialsCustomParser
| where Type in ("DNS_Summarized_Logs_ip_CL", "DNS_Summarized_Logs_ipV1_CL")
| where EventTime_t > min_t and EventResultDetails_s == 'NXDOMAIN'
| project-rename
SrcIpAddr=SrcIpAddr_s,
DnsQuery=DnsQuery_s,
Count=count__d,
EventTime=EventTime_t
| extend Count = toint(Count)
);
allData
| make-series QueryCount=dcount(DnsQuery) on EventTime from min_t to max_t step timeframe by SrcIpAddr
// include calculated Anomalies, Score and Baseline
| extend (anomalies, score, baseline) = series_decompose_anomalies(QueryCount, threshold, -1, 'linefit')
| mv-expand anomalies, score, baseline, EventTime, QueryCount
| extend
anomalies = toint(anomalies),
score = toint(score),
baseline = toint(baseline),
EventTime = todatetime(EventTime),
Total = tolong(QueryCount)
| where EventTime >= ago(timeframe)
| where score >= threshold * 2
// Join allData to include DnsQuery details
| join kind=inner(allData
| where TimeGenerated >= ago(timeframe)
| summarize DNSQueries = make_set(DnsQuery, 1000) by SrcIpAddr)
on SrcIpAddr
| project-away SrcIpAddr1
Declared entities
Related content
Links established from declared identifiers and solution manifests.
Source provenance
GitHubDisplayed values come from files in Azure/Azure-Sentinel. They describe the published template, not your workspace configuration.
- File
- Solutions/DNS Essentials/Analytic Rules/PotentialDGADetectedviaRepetitiveFailuresAnomalyBased.yaml ↗
- Commit
9800e51↗- Source identifier
01191239-274e-43c9-b154-3a042692af06
GSTEP / CATALOG TRACKING
Added to catalog : 16 Sept 2026 · 05:49 UTC
Last change observed : 16 Sept 2026 · 05:49 UTC