Cisco ASA - average attack detection rate increase

Status: available
Severity: low
Time window: 6h
Group by: DeviceEventClassID, DeviceName, DropRate, SourceIP, SourceOfDropRateCount
Source: github.com/Azure/Azure-Sentinel

'This will help you determine if Cisco ASA devices are under heavier attack than normal over the last hour versus the previous 6 hours based on DeviceEventClassID 733100 References: https://www.cisco.com/c/en/us/td/docs/security/asa/syslog/b_syslog/syslogs9.html Details on how to further troubleshoot/investigate: https://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-next-generation-firewalls/113685-asa-threat-detection.html'

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1046` Network Service Discovery
Impact	`T1498` Network Denial of Service

Rule body kusto

id: 79f29feb-6a9d-4cdf-baaa-2daf480a5da1
name: Cisco ASA - average attack detection rate increase
description: |
  'This will help you determine if Cisco ASA devices are under heavier attack than normal over the last hour versus the previous 6 hours based on DeviceEventClassID 733100
  References: https://www.cisco.com/c/en/us/td/docs/security/asa/syslog/b_syslog/syslogs9.html
  Details on how to further troubleshoot/investigate: https://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-next-generation-firewalls/113685-asa-threat-detection.html'
severity: Low
status: Available
requiredDataConnectors:
  - connectorId: CiscoAsaAma
    dataTypes:
      - CommonSecurityLog
queryFrequency: 1h
queryPeriod: 6h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Discovery
  - Impact
relevantTechniques:
  - T1046
  - T1498
query: |
  let timeframe = 1h;
  let last1h = CommonSecurityLog
  | where TimeGenerated >= ago(timeframe)
  | where isempty(CommunicationDirection)
  | where DeviceEventClassID == "733100"
  | extend SourceOfDropRateCount = tostring(split(tostring(split(Message, "]")[0]),"[ ")[1])
  | extend splitMessage = split(Message, ".")
  | extend DropRate = tostring(split(tostring(splitMessage[0]),"] ")[1])
  | extend CurrentBurstRate = split(tostring(split(tostring(splitMessage[1]),"  ")[0]),"is ")
  | extend CurrentBurstRatePerSec = toint(split(tostring(CurrentBurstRate[1])," ")[0])
  | extend MaxConfiguredBurstRate = toint(CurrentBurstRate[2])
  | extend CurrentAvgRate = split(tostring(split(tostring(splitMessage[1]),"  ")[1]),"is ")
  | extend CurrentAvgRatePerSec = toint(split(tostring(CurrentAvgRate[1])," ")[0])
  | extend MaxConfiguredAvgRate = toint(CurrentAvgRate[2])
  | extend CumulativeTotal = toint(split(tostring(split(tostring(splitMessage[1]),"  ")[2]),"is ")[1])
  | summarize last1hCumTotal = sum(CumulativeTotal), last1hAvgRatePerSec = avg(CurrentAvgRatePerSec), last1hAvgBurstRatePerSec = avg(CurrentBurstRatePerSec) by DeviceName, DeviceEventClassID, SourceIP, SourceOfDropRateCount, DropRate;
  let prev6h = CommonSecurityLog
  | where TimeGenerated between (ago(6h) .. ago(1h))
  | where isempty(CommunicationDirection)
  | where DeviceEventClassID == "733100"
  | extend SourceOfDropRateCount = tostring(split(tostring(split(Message, "]")[0]),"[ ")[1])
  | extend splitMessage = split(Message, ".")
  | extend DropRate = tostring(split(tostring(splitMessage[0]),"] ")[1])
  | extend CurrentBurstRate = split(tostring(split(tostring(splitMessage[1]),"  ")[0]),"is ")
  | extend prevCurrentBurstRatePerSec = toint(split(tostring(CurrentBurstRate[1])," ")[0])
  | extend prevMaxConfiguredBurstRate = toint(CurrentBurstRate[2])
  | extend CurrentAvgRate = split(tostring(split(tostring(splitMessage[1]),"  ")[1]),"is ")
  | extend prevCurrentAvgRatePerSec = toint(split(tostring(CurrentAvgRate[1])," ")[0])
  | extend prevMaxConfiguredAvgRate = toint(CurrentAvgRate[2])
  | extend prevCumulativeTotal = toint(split(tostring(split(tostring(splitMessage[1]),"  ")[2]),"is ")[1])
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), prev6hCumTotal = sum(prevCumulativeTotal), prev6hAvgRatePerSec = avg(prevCurrentAvgRatePerSec), prev6hAvgBurstRatePerSec = avg(prevCurrentBurstRatePerSec)
  by DeviceName, DeviceEventClassID, SourceIP, SourceOfDropRateCount, DropRate;
  last1h | join (
    prev6h
  ) on DeviceName, DeviceEventClassID, SourceIP, SourceOfDropRateCount, DropRate
  | project StartTimeUtc, EndTimeUtc, DeviceName, DeviceEventClassID, SourceIP, SourceOfDropRateCount, DropRate, last1hCumTotal, prev6hCumTotal, prev6hAvgCumTotal = prev6hCumTotal/6, last1hAvgRatePerSec, prev6hAvgRatePerSec, last1hAvgBurstRatePerSec, prev6hAvgBurstRatePerSec
  // Select only events that indicate a doubling of the expected rate in the last hour over the previous 6 hours
  | where last1hCumTotal > 2*prev6hAvgCumTotal or last1hAvgRatePerSec > 2*prev6hAvgRatePerSec or last1hAvgBurstRatePerSec > 2*prev6hAvgBurstRatePerSec
  | extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIP
version: 1.0.3
kind: Scheduled

Stages and Predicates

Parameters

let timeframe = 1h;

Let binding: `prev6h`

let prev6h = CommonSecurityLog
| where TimeGenerated between (ago(6h) .. ago(1h))
| where isempty(CommunicationDirection)
| where DeviceEventClassID == "733100"
| extend SourceOfDropRateCount = tostring(split(tostring(split(Message, "]")[0]),"[ ")[1])
| extend splitMessage = split(Message, ".")
| extend DropRate = tostring(split(tostring(splitMessage[0]),"] ")[1])
| extend CurrentBurstRate = split(tostring(split(tostring(splitMessage[1]),"  ")[0]),"is ")
| extend prevCurrentBurstRatePerSec = toint(split(tostring(CurrentBurstRate[1])," ")[0])
| extend prevMaxConfiguredBurstRate = toint(CurrentBurstRate[2])
| extend CurrentAvgRate = split(tostring(split(tostring(splitMessage[1]),"  ")[1]),"is ")
| extend prevCurrentAvgRatePerSec = toint(split(tostring(CurrentAvgRate[1])," ")[0])
| extend prevMaxConfiguredAvgRate = toint(CurrentAvgRate[2])
| extend prevCumulativeTotal = toint(split(tostring(split(tostring(splitMessage[1]),"  ")[2]),"is ")[1])
| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), prev6hCumTotal = sum(prevCumulativeTotal), prev6hAvgRatePerSec = avg(prevCurrentAvgRatePerSec), prev6hAvgBurstRatePerSec = avg(prevCurrentBurstRatePerSec)
by DeviceName, DeviceEventClassID, SourceIP, SourceOfDropRateCount, DropRate;

The stages below define let last1h (the rule's main pipeline source).

Stage 1: `source`

CommonSecurityLog

Stage 2: `where`

| where TimeGenerated >= ago(timeframe)

Stage 3: `where`

| where isempty(CommunicationDirection)

Stage 4: `where`

| where DeviceEventClassID == "733100"

Stage 5: `extend` (10 consecutive steps)

| extend SourceOfDropRateCount = tostring(split(tostring(split(Message, "]")[0]),"[ ")[1])
| extend splitMessage = split(Message, ".")
| extend DropRate = tostring(split(tostring(splitMessage[0]),"] ")[1])
| extend CurrentBurstRate = split(tostring(split(tostring(splitMessage[1]),"  ")[0]),"is ")
| extend CurrentBurstRatePerSec = toint(split(tostring(CurrentBurstRate[1])," ")[0])
| extend MaxConfiguredBurstRate = toint(CurrentBurstRate[2])
| extend CurrentAvgRate = split(tostring(split(tostring(splitMessage[1]),"  ")[1]),"is ")
| extend CurrentAvgRatePerSec = toint(split(tostring(CurrentAvgRate[1])," ")[0])
| extend MaxConfiguredAvgRate = toint(CurrentAvgRate[2])
| extend CumulativeTotal = toint(split(tostring(split(tostring(splitMessage[1]),"  ")[2]),"is ")[1])

Stage 6: `summarize`

| summarize last1hCumTotal = sum(CumulativeTotal), last1hAvgRatePerSec = avg(CurrentAvgRatePerSec), last1hAvgBurstRatePerSec = avg(CurrentBurstRatePerSec) by DeviceName, DeviceEventClassID, SourceIP, SourceOfDropRateCount, DropRate

The stages below run on last1h (the outer pipeline).

Stage 7: `join`

last1h
| join (
  prev6h
) on DeviceName, DeviceEventClassID, SourceIP, SourceOfDropRateCount, DropRate

Stage 8: `project`

| project StartTimeUtc, EndTimeUtc, DeviceName, DeviceEventClassID, SourceIP, SourceOfDropRateCount, DropRate, last1hCumTotal, prev6hCumTotal, prev6hAvgCumTotal = prev6hCumTotal/6, last1hAvgRatePerSec, prev6hAvgRatePerSec, last1hAvgBurstRatePerSec, prev6hAvgBurstRatePerSec

Stage 9: `where`

| where last1hCumTotal > 2*prev6hAvgCumTotal or last1hAvgRatePerSec > 2*prev6hAvgRatePerSec or last1hAvgBurstRatePerSec > 2*prev6hAvgBurstRatePerSec

Stage 10: `extend`

| extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))

Stage 11: `extend`

| extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)

HostNameDomain =

ifDomainIndex != -1substring(DeviceName, (DomainIndex + 1))

elseDeviceName

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
`CommunicationDirection`	is_null	(no value, null check)
`DeviceEventClassID`	eq	`733100` transforms: `cased`
`last1hAvgBurstRatePerSec`	cross_field_compare	`prev6hAvgBurstRatePerSec` transforms: `op:gt`, `rhs:mul:2`
`last1hAvgRatePerSec`	cross_field_compare	`prev6hAvgRatePerSec` transforms: `op:gt`, `rhs:mul:2`
`last1hCumTotal`	cross_field_compare	`prev6hAvgCumTotal` transforms: `op:gt`, `rhs:mul:2`

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
`DeviceEventClassID`	`project`
`DeviceName`	`project`
`DropRate`	`project`
`EndTimeUtc`	`project`
`SourceIP`	`project`
`SourceOfDropRateCount`	`project`
`StartTimeUtc`	`project`
`last1hAvgBurstRatePerSec`	`project`
`last1hAvgRatePerSec`	`project`
`last1hCumTotal`	`project`
`prev6hAvgBurstRatePerSec`	`project`
`prev6hAvgCumTotal`	`project`
`prev6hAvgRatePerSec`	`project`
`prev6hCumTotal`	`project`
`DomainIndex`	`extend`
`HostName`	`extend`
`HostNameDomain`	`extend`

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`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)

Cisco ASA - average attack detection rate increase

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: `prev6h`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `extend` (10 consecutive steps)

Stage 6: `summarize`

Stage 7: `join`

Stage 8: `project`

Stage 9: `where`

Stage 10: `extend`

Stage 11: `extend`

Indicators

Output fields

Keyboard shortcuts

Search operators

Cisco ASA - average attack detection rate increase

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: prev6h

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: extend (10 consecutive steps)

Stage 6: summarize

Stage 7: join

Stage 8: project

Stage 9: where

Stage 10: extend

Stage 11: extend

Indicators

Output fields

Let binding: `prev6h`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `extend` (10 consecutive steps)

Stage 6: `summarize`

Stage 7: `join`

Stage 8: `project`

Stage 9: `where`

Stage 10: `extend`

Stage 11: `extend`