Rare and potentially high-risk Office operations

Status: available
Severity: low
Time window: 1d
Source: github.com/Azure/Azure-Sentinel

Identifies Office operations that are typically rare and can provide capabilities useful to attackers.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1098` Account Manipulation
Collection	`T1114` Email Collection

Event coverage

Provider	Event
M365-ExchangeAdmin	New-ManagementRoleAssignment
M365-ExchangeAdmin	Set-Mailbox
M365-ExchangeAdmin	Set-TransportRule
M365-ExchangeItem	Add-MailboxFolderPermission
M365-ExchangeItem	Add-MailboxPermission
M365-ExchangeItem	New-InboxRule
M365-ExchangeItem	Set-InboxRule

Rules detecting the same action

Other rules on this platform that filter on the same API call or operation.

Inbox Rules Creation Or Update Activity in O365 (Sigma)
M365 Exchange Inbox Phishing Evasion Rule Created (Elastic)
Mail Forwarding/Redirecting Activity In O365 (Sigma)
Malicious BEC Inbox Rule (Kusto)

Rule body kusto

id: 957cb240-f45d-4491-9ba5-93430a3c08be
name: Rare and potentially high-risk Office operations
description: |
  'Identifies Office operations that are typically rare and can provide capabilities useful to attackers.'
severity: Low
status: Available
requiredDataConnectors:
  - connectorId: Office365
    dataTypes:
      - OfficeActivity
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Persistence
  - Collection
relevantTechniques:
  - T1098
  - T1114
query: |
  OfficeActivity
  | where Operation in~ ( "Add-MailboxPermission", "Add-MailboxFolderPermission", "Set-Mailbox", "New-ManagementRoleAssignment", "New-InboxRule", "Set-InboxRule", "Set-TransportRule")
  and not(UserId has_any ('NT AUTHORITY\\SYSTEM (Microsoft.Exchange.ServiceHost)', 'NT AUTHORITY\\SYSTEM (Microsoft.Exchange.AdminApi.NetCore)', 'NT AUTHORITY\\SYSTEM (w3wp)', 'devilfish-applicationaccount') and Operation in~ ( "Add-MailboxPermission", "Set-Mailbox"))
  | extend ClientIPOnly = tostring(extract_all(@'\[?(::ffff:)?(?P<IPAddress>(\d+\.\d+\.\d+\.\d+)|[^\]]+)\]?', dynamic(["IPAddress"]), ClientIP)[0])
  | extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: UserId
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: AccountUPNSuffix
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: ClientIP
  - entityType: CloudApplication
    fieldMappings:
      - identifier: AppId
        columnName: AppId
version: 2.0.5
kind: Scheduled

Stages and Predicates

Stage 1: `source`

OfficeActivity

Stage 2: `where`

| where Operation in~ ( "Add-MailboxPermission", "Add-MailboxFolderPermission", "Set-Mailbox", "New-ManagementRoleAssignment", "New-InboxRule", "Set-InboxRule", "Set-TransportRule")
and not(UserId has_any ('NT AUTHORITY\\SYSTEM (Microsoft.Exchange.ServiceHost)', 'NT AUTHORITY\\SYSTEM (Microsoft.Exchange.AdminApi.NetCore)', 'NT AUTHORITY\\SYSTEM (w3wp)', 'devilfish-applicationaccount') and Operation in~ ( "Add-MailboxPermission", "Set-Mailbox"))

Stage 3: `extend`

| extend ClientIPOnly = tostring(extract_all(@'\[?(::ffff:)?(?P<IPAddress>(\d+\.\d+\.\d+\.\d+)|[^\]]+)\]?', dynamic(["IPAddress"]), ClientIP)[0])

Stage 4: `extend`

| extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])

Exclusions

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

Field	Kind	Excluded values
`Operation`	in	`Add-MailboxPermission`, `Set-Mailbox`
`UserId`	match	`NT AUTHORITY\\SYSTEM (Microsoft.Exchange.ServiceHost)`, `NT AUTHORITY\\SYSTEM (Microsoft.Exchange.AdminApi.NetCore)`, `NT AUTHORITY\\SYSTEM (w3wp)`, `devilfish-applicationaccount`

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
`Operation`	in	`Add-MailboxFolderPermission` `Add-MailboxPermission` `New-InboxRule` `New-ManagementRoleAssignment` `Set-InboxRule` `Set-Mailbox` `Set-TransportRule`

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
`ClientIPOnly`	`extend`
`AccountName`	`extend`
`AccountUPNSuffix`	`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)

Rare and potentially high-risk Office operations

MITRE ATT&CK coverage

Event coverage

Rules detecting the same action

Rule body kusto

Stages and Predicates

Stage 1: `source`

Stage 2: `where`

Stage 3: `extend`

Stage 4: `extend`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Rare and potentially high-risk Office operations

MITRE ATT&CK coverage

Event coverage

Rules detecting the same action

Rule body kusto

Stages and Predicates

Stage 1: source

Stage 2: where

Stage 3: extend

Stage 4: extend

Exclusions

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `extend`

Stage 4: `extend`