Palo Alto - possible internal to external port scanning

Status: available
Severity: low
Time window: 1h
Group by: ApplicationProtocol, DestinationIP, DestinationPort, DeviceAction, DeviceName, DeviceProduct, DeviceVendor, Protocol, Reason, SourceIP, SourceUserID
Source: github.com/Azure/Azure-Sentinel

'Identifies a list of internal Source IPs (10.x.x.x Hosts) that have triggered 10 or more non-graceful tcp server resets from one or more Destination IPs which results in an "ApplicationProtocol = incomplete" designation. The server resets coupled with an "Incomplete" ApplicationProtocol designation can be an indication of internal to external port scanning or probing attack. References: https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClUvCAK and https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClTaCAK'

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1046` Network Service Discovery

Rule body kusto

id: 5b72f527-e3f6-4a00-9908-8e4fee14da9f
name: Palo Alto - possible internal to external port scanning
description: |
  'Identifies a list of internal Source IPs (10.x.x.x Hosts) that have triggered 10 or more non-graceful tcp server resets from one or more Destination IPs which results in an "ApplicationProtocol = incomplete" designation. The server resets coupled with an "Incomplete" ApplicationProtocol designation can be an indication of internal to external port scanning or probing attack.
  References: https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClUvCAK and
  https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClTaCAK'
severity: Low
status: Available
requiredDataConnectors:
  - connectorId: CefAma
    dataTypes:
      - CommonSecurityLog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Discovery
relevantTechniques:
  - T1046
query: |
  CommonSecurityLog
  | where isnotempty(DestinationPort) and DeviceAction !in ("reset-both", "deny")
  // filter out common usage ports. Add ports that are legitimate for your environment
  | where DestinationPort !in ("443", "53", "389", "80", "0", "880", "8888", "8080")
  | where ApplicationProtocol == "incomplete"
  // filter out IANA ephemeral or negotiated ports as per https://en.wikipedia.org/wiki/Ephemeral_port
  | where DestinationPort !between (toint(49512) .. toint(65535))
  | where Computer != ""
  | where ipv4_is_private(DestinationIP) == false
  | extend Reason = coalesce(
                                column_ifexists("Reason", ""),
                                extract("reason=(.+?)(;|$)", 1, AdditionalExtensions),
                                ""
                            )
  // Filter out any graceful reset reasons of AGED OUT which occurs when a TCP session closes with a FIN due to aging out.
  | where Reason !has "aged-out"
  // Filter out any TCP FIN which occurs when a TCP FIN is used to gracefully close half or both sides of a connection.
  | where Reason !has "tcp-fin"
  // Uncomment one of the following where clauses to trigger on specific TCP reset reasons
  // See Palo Alto article for details - https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClUvCAK
  // TCP RST-server - Occurs when the server sends a TCP reset to the client
  // | where AdditionalExtensions has "reason=tcp-rst-from-server"
  // TCP RST-client - Occurs when the client sends a TCP reset to the server
  // | where AdditionalExtensions has "reason=tcp-rst-from-client"
  // Already performed
  //| extend reason = tostring(split(AdditionalExtensions, ";")[3])
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), count() by DeviceName, SourceUserID, SourceIP, ApplicationProtocol, Reason, DestinationPort, Protocol, DeviceVendor, DeviceProduct, DeviceAction, DestinationIP
  | where count_ >= 10
  | summarize StartTimeUtc = min(StartTimeUtc), EndTimeUtc = max(EndTimeUtc), makeset(DestinationIP), totalcount = sum(count_) by DeviceName, SourceUserID, SourceIP, ApplicationProtocol, Reason, DestinationPort, Protocol, DeviceVendor, DeviceProduct, DeviceAction
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: SourceUserID
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIP
version: 1.0.8
kind: Scheduled

Stages and Predicates

Stage 1: `source`

CommonSecurityLog

Stage 2: `where`

| where isnotempty(DestinationPort) and DeviceAction !in ("reset-both", "deny")

Stage 3: `where`

| where DestinationPort !in ("443", "53", "389", "80", "0", "880", "8888", "8080")

Stage 4: `where`

| where ApplicationProtocol == "incomplete"

Stage 5: `where`

| where DestinationPort !between (toint(49512) .. toint(65535))

Stage 6: `where`

| where Computer != ""

Stage 7: `where`

| where ipv4_is_private(DestinationIP) == false

Stage 8: `extend`

| extend Reason = coalesce(
                              column_ifexists("Reason", ""),
                              extract("reason=(.+?)(;|$)", 1, AdditionalExtensions),
                              ""
                          )

Stage 9: `where`

| where Reason !has "aged-out"

Stage 10: `where`

| where Reason !has "tcp-fin"

Stage 11: `summarize`

| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), count() by DeviceName, SourceUserID, SourceIP, ApplicationProtocol, Reason, DestinationPort, Protocol, DeviceVendor, DeviceProduct, DeviceAction, DestinationIP

Stage 12: `where`

| where count_ >= 10

Stage 13: `summarize`

| summarize StartTimeUtc = min(StartTimeUtc), EndTimeUtc = max(EndTimeUtc), makeset(DestinationIP), totalcount = sum(count_) by DeviceName, SourceUserID, SourceIP, ApplicationProtocol, Reason, DestinationPort, Protocol, DeviceVendor, DeviceProduct, DeviceAction

Exclusions

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

Field	Kind	Excluded values
`DeviceAction`	in	`deny`, `reset-both`
`DestinationPort`	in	`0`, `389`, `443`, `53`, `80`, `8080`, `880`, `8888`
`DestinationPort`	ge	`49512`
`DestinationPort`	le	`65535`
`DestinationIP`	cidr_match	`10.0.0.0/8`, `172.16.0.0/12`, `192.168.0.0/16`, `169.254.0.0/16`, `127.0.0.0/8`
`Reason`	match	`aged-out`
`Reason`	match	`tcp-fin`

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
`ApplicationProtocol`	eq	`incomplete` transforms: `cased`
`DestinationPort`	is_not_null	(no value, null check)
`count_`	ge	`10` 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.

Field	Source
`ApplicationProtocol`	`summarize`
`DestinationPort`	`summarize`
`DeviceAction`	`summarize`
`DeviceName`	`summarize`
`DeviceProduct`	`summarize`
`DeviceVendor`	`summarize`
`EndTimeUtc`	`summarize`
`Protocol`	`summarize`
`Reason`	`summarize`
`SourceIP`	`summarize`
`SourceUserID`	`summarize`
`StartTimeUtc`	`summarize`
`totalcount`	`summarize`

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`f`	Follow link (`Shift` = new tab)
`/`	Focus search
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`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)

Palo Alto - possible internal to external port scanning

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `where`

Stage 7: `where`

Stage 8: `extend`

Stage 9: `where`

Stage 10: `where`

Stage 11: `summarize`

Stage 12: `where`

Stage 13: `summarize`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Palo Alto - possible internal to external port scanning

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: where

Stage 6: where

Stage 7: where

Stage 8: extend

Stage 9: where

Stage 10: where

Stage 11: summarize

Stage 12: where

Stage 13: summarize

Exclusions

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `where`

Stage 7: `where`

Stage 8: `extend`

Stage 9: `where`

Stage 10: `where`

Stage 11: `summarize`

Stage 12: `where`

Stage 13: `summarize`