Hijack Execution Flow - DLL Side-Loading

Status: available
Severity: medium
Time window: 1h
Source: github.com/Azure/Azure-Sentinel

This detection tries to identify all DLLs loaded by "high integrity" processes and cross-checks the DLL paths against FileCreate/FileModify events of the same DLL by a medium integrity process. Of course, we need to do some magic to filter out false positives as much as possible. So any FileCreate/FileModify done by "NT Authoriy\System" and the "RID 500" users aren't interesting. Also, we only want to see the FileCreate/FileModify actions which are performed with a default or limited token elevation. If done with a full elevated token, the user is apparently admin already.

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1574.002` Hijack Execution Flow: DLL Side-Loading

Event coverage

Provider	Event/ActionType	Title
Sysmon	Event ID 7	Image loaded
Defender-DeviceImageLoadEvents	any	Image load (any)

Rule body kusto

id: 3084b487-fad6-4000-9544-6085b9657290
name: Hijack Execution Flow - DLL Side-Loading
description: |
  This detection tries to identify all DLLs loaded by "high integrity" processes and cross-checks the DLL paths against FileCreate/FileModify events of the same DLL by a medium integrity process.
  Of course, we need to do some magic to filter out false positives as much as possible. So any FileCreate/FileModify done by "NT Authoriy\System" and the "RID 500" users aren't interesting.
  Also, we only want to see the FileCreate/FileModify actions which are performed with a default or limited token elevation. If done with a full elevated token, the user is apparently admin already.
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceFileEvents
      - DeviceImageLoadEvents
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Persistence
  - PrivilegeEscalation
  - DefenseEvasion
relevantTechniques:
  - T1574.002
query: |
  let imls = materialize(
      DeviceImageLoadEvents
      | where InitiatingProcessIntegrityLevel in ("High", "System") and FileName !endswith ".exe"
      | project FolderPath=tolower(FolderPath), InitiatingProcessFileName, InitiatingProcessIntegrityLevel, DeviceId, DeviceName
      | distinct FolderPath, InitiatingProcessFileName, InitiatingProcessIntegrityLevel, DeviceId, DeviceName
  );
  imls
  | join (
      DeviceFileEvents
      | where FolderPath in~ ((imls | project FolderPath)) and ActionType in ("FileCreated", "FileModified") and
      InitiatingProcessIntegrityLevel !in ("High", "System", "") and InitiatingProcessAccountSid != "S-1-5-18" and
      InitiatingProcessTokenElevation in ("TokenElevationTypeDefault", "TokenElevationTypeLimited") and InitiatingProcessAccountSid !endswith "-500"
      | extend FolderPath=tolower(FolderPath)
  ) on FolderPath, DeviceId, DeviceName
  | project-away FolderPath1
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
  - entityType: Account
    fieldMappings:
      - identifier: Sid
        columnName: InitiatingProcessAccountSid
      - identifier: Name
        columnName: InitiatingProcessAccountName
      - identifier: NTDomain
        columnName: InitiatingProcessAccountDomain
  - entityType: Process
    fieldMappings:
      - identifier: CommandLine
        columnName: InitiatingProcessCommandLine
version: 1.0.1
kind: Scheduled

Stages and Predicates

Stage 0: `let`

let imls = materialize(<inlined as stages below>);

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

Stage 1: `source`

DeviceImageLoadEvents

Stage 2: `where`

| where InitiatingProcessIntegrityLevel in ("High", "System") and FileName !endswith ".exe"

Stage 3: `project`

| project FolderPath=tolower(FolderPath), InitiatingProcessFileName, InitiatingProcessIntegrityLevel, DeviceId, DeviceName

Stage 4: `distinct`

| distinct FolderPath, InitiatingProcessFileName, InitiatingProcessIntegrityLevel, DeviceId, DeviceName

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

Stage 5: `join`

imls
| join (
    DeviceFileEvents
    | where FolderPath in~ ((imls | project FolderPath)) and ActionType in ("FileCreated", "FileModified") and
    InitiatingProcessIntegrityLevel !in ("High", "System", "") and InitiatingProcessAccountSid != "S-1-5-18" and
    InitiatingProcessTokenElevation in ("TokenElevationTypeDefault", "TokenElevationTypeLimited") and InitiatingProcessAccountSid !endswith "-500"
    | extend FolderPath=tolower(FolderPath)
) on FolderPath, DeviceId, DeviceName

Stage 6: `project-away`

| project-away FolderPath1

Exclusions

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

Field	Kind	Excluded values
`FileName`	ends_with	`.exe`
`InitiatingProcessAccountSid`	ends_with	`-500`
`InitiatingProcessIntegrityLevel`	in	`High`, `System`

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`	in	`FileCreated` transforms: `cased` corpus 8 (kusto 8) `FileModified` transforms: `cased`
`InitiatingProcessAccountSid`	ne	`S-1-5-18` transforms: `cased`
`InitiatingProcessIntegrityLevel`	in	`High` transforms: `cased` corpus 21 (sigma 17, kusto 3, splunk 1) `System` transforms: `cased` corpus 29 (sigma 22, splunk 4, elastic 3)
`InitiatingProcessTokenElevation`	in	`TokenElevationTypeDefault` transforms: `cased` `TokenElevationTypeLimited` 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
`DeviceId`	`project`
`DeviceName`	`project`
`FolderPath`	`project`
`InitiatingProcessFileName`	`project`
`InitiatingProcessIntegrityLevel`	`project`

`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)

Hijack Execution Flow - DLL Side-Loading

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Stage 0: `let`

Stage 1: `source`

Stage 2: `where`

Stage 3: `project`

Stage 4: `distinct`

Stage 5: `join`

Stage 6: `project-away`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Hijack Execution Flow - DLL Side-Loading

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Stage 0: let

Stage 1: source

Stage 2: where

Stage 3: project

Stage 4: distinct

Stage 5: join

Stage 6: project-away

Exclusions

Indicators

Output fields

Stage 0: `let`

Stage 1: `source`

Stage 2: `where`

Stage 3: `project`

Stage 4: `distinct`

Stage 5: `join`

Stage 6: `project-away`