Exchange Worker Process Making Remote Call

Severity: medium
Time window: 1d
Author: Microsoft Security Community
Source: github.com/Azure/Azure-Sentinel

This query dynamically identifies Exchange servers and then looks for instances where the IIS worker process initiates a call out to a remote URL using either cmd.exe or powershell.exe. This behaviour was described as post-compromise behaviour following exploitation of CVE-2022-41040 and CVE-2022-41082, this pattern of activity was use to download additional tools to the server. This suspicious activity is generic.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell, `T1059.003` Command and Scripting Interpreter: Windows Command Shell

Event coverage

Provider	Event/ActionType	Title
Sysmon	Event ID 1	Process creation
Security-Auditing	Event ID 4688	A new process has been created.
Defender-DeviceProcessEvents	any	Process activity (any)

Rule body kusto

id: 2c701f94-783c-4cd4-bc9b-3b3334976090
name: Exchange Worker Process Making Remote Call
description: |
  'This query dynamically identifies Exchange servers and then looks for instances where the IIS worker process initiates a call out to a remote URL using either cmd.exe or powershell.exe.
  This behaviour was described as post-compromise behaviour following exploitation of CVE-2022-41040 and CVE-2022-41082, this pattern of activity was use to download additional tools to the server. This suspicious activity is generic.'
severity: Medium
requiredDataConnectors:
  - connectorId: AzureMonitor(IIS)
    dataTypes:
      - W3CIISLog
  - connectorId: MicrosoftThreatProtection
    dataTypes:
    - DeviceProcessEvents
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt 
triggerThreshold: 0
tactics:
  - Execution
relevantTechniques:
  - T1059.001
  - T1059.003
query: |
  let suspiciousCmdLineKeywords = dynamic(["http://", "https://"]);
  // Identify exchange servers based on known paths
  // Summarize these to get a list of exchange server hostnames
  let exchangeServers = W3CIISLog
  | where csUriStem has_any("/owa/","/ews/","/ecp/","/autodiscover/")
  // Only where successful, rule out failed scanning
  | where scStatus startswith "2"
  | summarize by Computer;
  DeviceProcessEvents
  | where DeviceName in~ (exchangeServers)
  // Where the IIS worker process initiated CMD or PowerShell
  | where InitiatingProcessParentFileName == "w3wp.exe"
  | where InitiatingProcessFileName has_any("cmd.exe", "powershell.exe")
  // Where CMD or PowerShell command line included parameters associated with CVE-2022-41040/CVE-2022-41082 exploitation
  | where ProcessCommandLine has_any(suspiciousCmdLineKeywords)
  | project TimeGenerated, DeviceId, DeviceName, InitiatingProcessFileName, ProcessCommandLine, AccountDomain = InitiatingProcessAccountDomain, AccountName = InitiatingProcessAccountName
  | extend Account = strcat(AccountDomain, "\\", AccountName)
  | extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: Account
      - identifier: Name
        columnName: AccountName
      - identifier: NTDomain
        columnName: AccountDomain
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
      - identifier: HostName
        columnName: HostName
      - identifier: NTDomain
        columnName: HostNameDomain
version: 1.1.2
kind: Scheduled
metadata:
    source:
        kind: Community
    author:
        name: Microsoft Security Community
    support:
        tier: Community
    categories:
        domains: [ "Application" ]

Stages and Predicates

Parameters

let suspiciousCmdLineKeywords = dynamic(["http://", "https://"]);

Let binding: `exchangeServers`

let exchangeServers = W3CIISLog
| where csUriStem has_any("/owa/","/ews/","/ecp/","/autodiscover/")
| where scStatus startswith "2"
| summarize by Computer;

Stage 1: `source`

DeviceProcessEvents

Stage 2: `where`

| where DeviceName in~ (exchangeServers)

References exchangeServers (defined above).

Stage 3: `where`

| where InitiatingProcessParentFileName == "w3wp.exe"

Stage 4: `where`

| where InitiatingProcessFileName has_any("cmd.exe", "powershell.exe")

Stage 5: `where`

| where ProcessCommandLine has_any(suspiciousCmdLineKeywords)

Stage 6: `project`

| project TimeGenerated, DeviceId, DeviceName, InitiatingProcessFileName, ProcessCommandLine, AccountDomain = InitiatingProcessAccountDomain, AccountName = InitiatingProcessAccountName

Stage 7: `extend` (3 consecutive steps)

| extend Account = strcat(AccountDomain, "\\", AccountName)
| extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)

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
`DeviceName`	in	`exchangeServers`
`InitiatingProcessFileName`	match	`cmd.exe` corpus 2 (kusto 2) `powershell.exe` corpus 2 (kusto 2)
`InitiatingProcessParentFileName`	eq	`w3wp.exe` transforms: `cased`
`ProcessCommandLine`	match	`http://` corpus 21 (sigma 18, elastic 1, splunk 1, kusto 1) `https://` corpus 21 (sigma 18, elastic 1, splunk 1, kusto 1)

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
`AccountDomain`	`project`
`AccountName`	`project`
`DeviceId`	`project`
`DeviceName`	`project`
`InitiatingProcessFileName`	`project`
`ProcessCommandLine`	`project`
`TimeGenerated`	`project`
`Account`	`extend`
`DomainIndex`	`extend`
`HostName`	`extend`
`HostNameDomain`	`extend`

`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)

Exchange Worker Process Making Remote Call

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: `exchangeServers`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `project`

Stage 7: `extend` (3 consecutive steps)

Indicators

Output fields

Keyboard shortcuts

Search operators

Exchange Worker Process Making Remote Call

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: exchangeServers

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: where

Stage 6: project

Stage 7: extend (3 consecutive steps)

Indicators

Output fields

Let binding: `exchangeServers`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `project`

Stage 7: `extend` (3 consecutive steps)