Port Scan

Status: available
Severity: medium
Time window: 30s
Group by: Fqdn, SourceIp
Source: github.com/Azure/Azure-Sentinel

'Identifies a source IP scanning multiple open ports on Azure Firewall. This can indicate malicious scanning of ports by an attacker, trying to reveal open ports in the organization that can be compromised for initial access. Configurable Parameters: - Port scan time - the time range to look for multiple ports scanned. Default is set to 30 seconds. - Minimum different ports threshold - alert only if more than this number of ports scanned. Default is set to 100.'

MITRE ATT&CK coverage

Tactic	Techniques
Reconnaissance	`T1595.001` Active Scanning: Scanning IP Blocks
Discovery	`T1046` Network Service Discovery

Rule body kusto

id: b2c5907b-1040-4692-9802-9946031017e8
name: Port Scan
description: |
  'Identifies a source IP scanning multiple open ports on Azure Firewall. This can indicate malicious scanning of ports by an attacker, trying to reveal open ports in the organization that can be compromised for initial access.

  Configurable Parameters:

  - Port scan time - the time range to look for multiple ports scanned. Default is set to 30 seconds.
  - Minimum different ports threshold - alert only if more than this number of ports scanned. Default is set to 100.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: AzureFirewall
    dataTypes:
      - AzureDiagnostics
      - AZFWApplicationRule
      - AZFWNetworkRule
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Discovery
  - Reconnaissance
relevantTechniques:
  - T1046
  - T1595.001
query: |
  let MinimumDifferentPortsThreshold = 100;
  let BinTime = 30s;
  // Exclude known benign scanner IPs in your environment to reduce noise
  let KnownScannerIPs = dynamic([]); 
  union isfuzzy=true(
  AZFWApplicationRule
  | where SourceIp !in (KnownScannerIPs)
  | summarize AlertTimedCountPortsInBinTime = dcount(DestinationPort) by SourceIp, bin(TimeGenerated, BinTime), Fqdn
  | where AlertTimedCountPortsInBinTime > MinimumDifferentPortsThreshold),
  (AZFWNetworkRule
  | where SourceIp !in (KnownScannerIPs)
  | extend Fqdn = DestinationIp
  | summarize AlertTimedCountPortsInBinTime = dcount(DestinationPort) by SourceIp, bin(TimeGenerated, BinTime), Fqdn
  | where AlertTimedCountPortsInBinTime > MinimumDifferentPortsThreshold),
  (AzureDiagnostics
  | where OperationName == "AzureFirewallApplicationRuleLog" or OperationName == "AzureFirewallNetworkRuleLog"
  | parse msg_s with * "from " SourceIp ":" SourcePort:int " to " Fqdn ":" DestinationPort:int *
  | where isnotempty(Fqdn) and isnotempty(SourceIp)
  | where SourceIp !in (KnownScannerIPs) 
  | summarize AlertTimedCountPortsInBinTime = dcount(DestinationPort) by SourceIp, bin(TimeGenerated, BinTime), Fqdn
  | where AlertTimedCountPortsInBinTime > MinimumDifferentPortsThreshold)
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIp
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Fqdn
alertDetailsOverride:
  alertDisplayNameFormat: 'Port Scan Detected from {{SourceIp}}'
  alertDescriptionFormat: 'Source IP {{SourceIp}} has scanned {{AlertTimedCountPortsInBinTime}} different ports within a short time frame, which may indicate reconnaissance activity.'
version: 1.1.3
kind: Scheduled

Stages and Predicates

Parameters

let MinimumDifferentPortsThreshold = 100;
let BinTime = 30s;
let KnownScannerIPs = dynamic([]);

union `isfuzzy=true` (3 sources)

Each leg below queries one source; the rule matches if any leg does. Sources: AZFWApplicationRule, AZFWNetworkRule, AzureDiagnostics

Leg 1: `AZFWApplicationRule`

AZFWApplicationRule
| where SourceIp !in (KnownScannerIPs)
| summarize AlertTimedCountPortsInBinTime = dcount(DestinationPort) by SourceIp, bin(TimeGenerated, BinTime), Fqdn
| where AlertTimedCountPortsInBinTime > MinimumDifferentPortsThreshold

Leg 2: `AZFWNetworkRule`

AZFWNetworkRule
| where SourceIp !in (KnownScannerIPs)
| extend Fqdn = DestinationIp
| summarize AlertTimedCountPortsInBinTime = dcount(DestinationPort) by SourceIp, bin(TimeGenerated, BinTime), Fqdn
| where AlertTimedCountPortsInBinTime > MinimumDifferentPortsThreshold

Leg 3: `AzureDiagnostics`

AzureDiagnostics
| where OperationName == "AzureFirewallApplicationRuleLog" or OperationName == "AzureFirewallNetworkRuleLog"
| parse msg_s with * "from " SourceIp ":" SourcePort:int " to " Fqdn ":" DestinationPort:int *
| where isnotempty(Fqdn) and isnotempty(SourceIp)
| where SourceIp !in (KnownScannerIPs) 
| summarize AlertTimedCountPortsInBinTime = dcount(DestinationPort) by SourceIp, bin(TimeGenerated, BinTime), Fqdn
| where AlertTimedCountPortsInBinTime > MinimumDifferentPortsThreshold

Exclusions

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

Field	Kind	Excluded values
`SourceIp`	eq	`[]`
`SourceIp`	eq	`[]`
`SourceIp`	eq	`[]`

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
`AlertTimedCountPortsInBinTime`	gt	`100` transforms: `cased`
`Fqdn`	is_not_null	(no value, null check)
`OperationName`	eq	`AzureFirewallApplicationRuleLog` transforms: `cased` `AzureFirewallNetworkRuleLog` transforms: `cased`
`SourceIp`	is_not_null	(no value, null check)

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
`AlertTimedCountPortsInBinTime`	`summarize`
`Fqdn`	`summarize`
`SourceIp`	`summarize`

`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)

Port Scan

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

union `isfuzzy=true` (3 sources)

Leg 1: `AZFWApplicationRule`

Leg 2: `AZFWNetworkRule`

Leg 3: `AzureDiagnostics`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Port Scan

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

union isfuzzy=true (3 sources)

Leg 1: AZFWApplicationRule

Leg 2: AZFWNetworkRule

Leg 3: AzureDiagnostics

Exclusions

Indicators

Output fields

union `isfuzzy=true` (3 sources)

Leg 1: `AZFWApplicationRule`

Leg 2: `AZFWNetworkRule`

Leg 3: `AzureDiagnostics`