Suspicious Network Connections - Supply Chain Attack

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

Below query detects unusual network conenctions from servers that have 3rd party software installed.
You can further improve the query by using a list of servers that have privileges across the whole domain.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	No specific technique

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	any	Network activity (any)

Rule body kusto

// Author: Cyb3rMonk(https://twitter.com/Cyb3rMonk, https://mergene.medium.com)
//
// Query parameters:
let lookback = 14d; 
// Generate list of all Servers
let server_list = 
    DeviceInfo
    | where Timestamp > ago(lookback)
    | where isnotempty(OSPlatform)
    | where DeviceType <> "Workstation" and OSPlatform <> "macOS"
    | summarize make_set(DeviceName)
    ;
// Generate list of servers that have 3rd party software installed.
// Criteria: if a software is installed on less than 10 servers, it's probably a 3rd party software.
// There are probably(hopefully) just a few servers or server groups that have privileges across the whole domain.
// You can change the threshold according to your environment.
let ServersWithThirdPartyApps = materialize (
    DeviceNetworkEvents
    | where Timestamp > ago(lookback)
    | where DeviceName in (server_list)
    | where ActionType <> "ListeningConnectionCreated"
    | where RemoteIPType !in ("Private","Loopback") and (not (RemoteIPType == "FourToSixMapping" and RemoteIP startswith "::ffff:"))
    | summarize dcount(DeviceName) by InitiatingProcessVersionInfoCompanyName
    | where dcount_DeviceName < 10
    | join kind=inner (
        DeviceNetworkEvents
        | where Timestamp > ago(lookback)
        | where DeviceName in (server_list)
        | where ActionType <> "ListeningConnectionCreated"
        | where RemoteIPType !in ("Private","Loopback") and (not (RemoteIPType == "FourToSixMapping" and RemoteIP startswith "::ffff:"))
        )
        on InitiatingProcessVersionInfoCompanyName
        | summarize make_set(DeviceName)
        )
        ;
// Get network connection statistics
let baseline = materialize (
    DeviceNetworkEvents
    | where Timestamp > ago(lookback)
    | where DeviceName in (ServersWithThirdPartyApps)
    | where ActionType <> "ListeningConnectionCreated"
    | where RemoteIPType !in ("Private","Loopback") and (not (RemoteIPType == "FourToSixMapping" and RemoteIP startswith "::ffff:"))
    | summarize hint.strategy=shuffle Count=count(), starttime = min(Timestamp), endtime = max(Timestamp) by DeviceName, RemoteIP, RemotePort
    )
    ;
// Get destination IP 
let Destinations = baseline | summarize make_set(RemoteIP);
// Filter connections that was not seen before last 1d 
// Generate prevalence info, URL info(if available) and enrich results
// Filter based on prevalence and URL information and display everything by hostname
baseline
| where starttime > ago(1d)
| lookup kind=leftouter (
    DeviceNetworkEvents
    | where Timestamp > ago(5d)
    | where RemoteIP in (Destinations)
    | summarize hint.strategy=shuffle Prevalence = dcount(DeviceId), URLs=make_set(RemoteUrl) by RemoteIP
    )
    on RemoteIP
| where Prevalence < 6 or isempty( Prevalence)
// If you want to see all the events in distinct rows, remove the below 2 lines
// filter out results based on trusted URLs if you like. 
| extend Details = pack('RemoteIP',RemoteIP, 'RemotePort',RemotePort, 'Count',Count, 'Prevalence',Prevalence, 'URLs',URLs)
| summarize make_set(Details) by DeviceName

Stages and Predicates

Parameters

let lookback = 14d;

Let binding: `server_list`

let server_list = DeviceInfo
    | where Timestamp > ago(lookback)
    | where isnotempty(OSPlatform)
    | where DeviceType <> "Workstation" and OSPlatform <> "macOS"
    | summarize make_set(DeviceName);

Derived from lookback.

Let binding: `ServersWithThirdPartyApps`

let ServersWithThirdPartyApps = materialize (
    DeviceNetworkEvents
    | where Timestamp > ago(lookback)
    | where DeviceName in (server_list)
    | where ActionType <> "ListeningConnectionCreated"
    | where RemoteIPType !in ("Private","Loopback") and (not (RemoteIPType == "FourToSixMapping" and RemoteIP startswith "::ffff:"))
    | summarize dcount(DeviceName) by InitiatingProcessVersionInfoCompanyName
    | where dcount_DeviceName < 10
    | join kind=inner (
        DeviceNetworkEvents
        | where Timestamp > ago(lookback)
        | where DeviceName in (server_list)
        | where ActionType <> "ListeningConnectionCreated"
        | where RemoteIPType !in ("Private","Loopback") and (not (RemoteIPType == "FourToSixMapping" and RemoteIP startswith "::ffff:"))
        )
        on InitiatingProcessVersionInfoCompanyName
        | summarize make_set(DeviceName)
        );

Derived from lookback, server_list.

Let binding: `Destinations`

let Destinations = baseline | summarize make_set(RemoteIP);

Derived from baseline.

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

Stage 1: `source`

DeviceNetworkEvents

Stage 2: `where`

| where Timestamp > ago(lookback)

Stage 3: `where`

| where DeviceName in (ServersWithThirdPartyApps)

References ServersWithThirdPartyApps (defined above).

Stage 4: `where`

| where ActionType <> "ListeningConnectionCreated"

Stage 5: `where`

| where RemoteIPType !in ("Private","Loopback") and (not (RemoteIPType == "FourToSixMapping" and RemoteIP startswith "::ffff:"))

Stage 6: `summarize`

| summarize hint.strategy=shuffle Count=count(), starttime = min(Timestamp), endtime = max(Timestamp) by DeviceName, RemoteIP, RemotePort

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

Stage 7: `where`

baseline
| where starttime > ago(1d)

Stage 8: `kusto:lookup`

| lookup kind=leftouter (
    DeviceNetworkEvents
    | where Timestamp > ago(5d)
    | where RemoteIP in (Destinations)
    | summarize hint.strategy=shuffle Prevalence = dcount(DeviceId), URLs=make_set(RemoteUrl) by RemoteIP
    )
    on RemoteIP

Stage 9: `where`

| where Prevalence < 6 or isempty( Prevalence)

Stage 10: `extend`

| extend Details = pack('RemoteIP',RemoteIP, 'RemotePort',RemotePort, 'Count',Count, 'Prevalence',Prevalence, 'URLs',URLs)

Stage 11: `summarize`

| summarize make_set(Details) by DeviceName

Exclusions

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

Field	Kind	Excluded values
`RemoteIP`	starts_with	`::ffff:`
`RemoteIPType`	eq	`FourToSixMapping`
`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`	ne	`ListeningConnectionCreated` transforms: `cased` corpus 3 (kusto 3)
`DeviceName`	in	`ServersWithThirdPartyApps` transforms: `cased`
`Prevalence`	is_null	(no value, null check)
`Prevalence`	lt	`6` transforms: `cased`
`RemoteIP`	in	`Destinations` 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
`DeviceName`	`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)

Suspicious Network Connections - Supply Chain Attack

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: `server_list`

Let binding: `ServersWithThirdPartyApps`

Let binding: `Destinations`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `summarize`

Stage 7: `where`

Stage 8: `kusto:lookup`

Stage 9: `where`

Stage 10: `extend`

Stage 11: `summarize`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Suspicious Network Connections - Supply Chain Attack

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: server_list

Let binding: ServersWithThirdPartyApps

Let binding: Destinations

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: where

Stage 6: summarize

Stage 7: where

Stage 8: kusto:lookup

Stage 9: where

Stage 10: extend

Stage 11: summarize

Exclusions

Indicators

Output fields

Let binding: `server_list`

Let binding: `ServersWithThirdPartyApps`

Let binding: `Destinations`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `summarize`

Stage 7: `where`

Stage 8: `kusto:lookup`

Stage 9: `where`

Stage 10: `extend`

Stage 11: `summarize`