Server Network Connection Anomalies

Group by: RemoteIP
Author: Cyb3rMonk
Source: github.com/Cyb3r-Monk/Threat-Hunting-and-Detection

Servers have a specific baseline. This makes it easy to create a baseline and detect anomalies.
Below queries analyze the network connections made by the specified servers and detects the rare/anomalous ones.
You can add process info to the analysis, but it will probably generate more results(different processes for the same IP).

Event coverage

Provider	Event/ActionType	Title
Sysmon	Event ID 3	Network connection
Security-Auditing	Event ID 5156	The Windows Filtering Platform has permitted a connection.
Defender-DeviceNetworkEvents	ConnectionSuccess	Connection succeeded

Rule body kusto

// Define servers you want to monitor. 
let Servers = dynamic(["server1","server2","etc."]);
// Get rare connections by RemoteIP and InitiatingProcessFileName
DeviceNetworkEvents
| where Timestamp > ago(30d)
| where DeviceName in (Servers) and ActionType == "ConnectionSuccess"
| where RemoteIPType !in ( "Private", "Loopback" )
| where RemoteIP !startswith "169.254."
| summarize make_set(RemoteUrl), count() by RemoteIP
| where count_ < 50
// Exclude traffic to known destinations.
| where not ( set_RemoteUrl has_any (".microsoft.com",".windowsupdate.com","login.microsoftonline.com","login.live.com","autodiscover-s.outlook.com","ocsp.digicert.com","ocsp.verisign.com","login.windows.net", "outlook.office365.com","accounts.accesscontrol.windows.net"))
// Get details of the connections that were made in the last 5 days.
// If you are going to check the results everyday, change the threshold to 1d. 
| join kind=inner
    (
    DeviceNetworkEvents
    | where Timestamp > ago(5d)
    | where DeviceName in (Servers) and ActionType == "ConnectionSuccess"
    | where RemoteIPType !in ( "Private", "Loopback" )
    | where RemoteIP !startswith "169.254."
    ) on RemoteIP

// Define servers you want to monitor. 
let Servers = dynamic(["server1","server2","etc."]);
// Get rare connections by DestinationIp
let _lookback = 30d;
let _timeframe = 5d;
let PrivateIPregex = @'^127\.|^10\.|^172\.1[6-9]\.|^172\.2[0-9]\.|^172\.3[0-1]\.|^192\.168\.';
// Parse Sysmon network connections and get only the ones towards the internet.
let parse_sysmon_id3 = (T:(TimeGenerated:datetime,EventID:int, Source:string,RenderedDescription:string, EventData:string))
{
T 
| where TimeGenerated > ago(_lookback)
| where Source == "Microsoft-Windows-Sysmon" and EventID == 3
| extend RenderedDescription = tostring(split(RenderedDescription, ":")[0])
| extend EventData = parse_xml(EventData).DataItem.EventData.Data
| mv-expand bagexpansion=array EventData
| evaluate bag_unpack(EventData)
| extend Key=tostring(['@Name']), Value=tostring(['#text'])
| evaluate pivot(Key, any(Value), TimeGenerated, Source, EventLog, Computer, EventLevel, EventLevelName, EventID, UserName, RenderedDescription, MG, ManagementGroupName, Type, _ResourceId)
| extend RuleName = column_ifexists("RuleName", ""), TechniqueId = column_ifexists("TechniqueId", ""),  TechniqueName = column_ifexists("TechniqueName", "")
| parse RuleName with * 'technique_id=' TechniqueId ',' * 'technique_name=' TechniqueName
// Filter connections towards the internet
| where not (DestinationIp matches regex PrivateIPregex)
};
// Get rare connections by DestinationIp
Event
| where TimeGenerated > ago(_lookback)
| where Computer in (Servers)
| invoke parse_sysmon_id3()
| summarize count() by DestinationIp
| where count_ < 50
// get details of the rare connections for further analysis.
| join kind=inner
    (
    Event
    | where TimeGenerated > ago(_timeframe)
    | where Computer in (Servers)
    | invoke parse_sysmon_id3()
    ) on DestinationIp

Stages and Predicates

Parameters

let Servers = dynamic(["server1","server2","etc."]);

Stage 1: `source`

DeviceNetworkEvents

Stage 2: `where`

| where Timestamp > ago(30d)

Stage 3: `where`

| where DeviceName in (Servers) and ActionType == "ConnectionSuccess"

Stage 4: `where`

| where RemoteIPType !in ( "Private", "Loopback" )

Stage 5: `where`

| where RemoteIP !startswith "169.254."

Stage 6: `summarize`

| summarize make_set(RemoteUrl), count() by RemoteIP

Stage 7: `where`

| where count_ < 50

Stage 8: `where`

| where not ( set_RemoteUrl has_any (".microsoft.com",".windowsupdate.com","login.microsoftonline.com","login.live.com","autodiscover-s.outlook.com","ocsp.digicert.com","ocsp.verisign.com","login.windows.net", "outlook.office365.com","accounts.accesscontrol.windows.net"))

Stage 9: `join`

| join kind=inner
    (
    DeviceNetworkEvents
    | where Timestamp > ago(5d)
    | where DeviceName in (Servers) and ActionType == "ConnectionSuccess"
    | where RemoteIPType !in ( "Private", "Loopback" )
    | where RemoteIP !startswith "169.254."
    ) on RemoteIP

Exclusions

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

Field	Kind	Excluded values
`RemoteIPType`	in	`Loopback`, `Private`
`RemoteIP`	starts_with	`169.254.`
`set_RemoteUrl`	match	`.microsoft.com`, `.windowsupdate.com`, `login.microsoftonline.com`, `login.live.com`, `autodiscover-s.outlook.com`, `ocsp.digicert.com`, `ocsp.verisign.com`, `login.windows.net`, `outlook.office365.com`, `accounts.accesscontrol.windows.net`
`RemoteIP`	starts_with	`169.254.`
`RemoteIPType`	in	`Loopback`, `Private`

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
`ActionType`	eq	`ConnectionSuccess` transforms: `cased` corpus 9 (kusto 9)
`DeviceName`	in	`etc.` transforms: `cased` `server1` transforms: `cased` `server2` transforms: `cased`
`count_`	lt	`50` 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
`RemoteIP`	`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)

Server Network Connection Anomalies

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `summarize`

Stage 7: `where`

Stage 8: `where`

Stage 9: `join`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Server Network Connection Anomalies

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: where

Stage 6: summarize

Stage 7: where

Stage 8: where

Stage 9: join

Exclusions

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `summarize`

Stage 7: `where`

Stage 8: `where`

Stage 9: `join`