Dev-0530 File Extension Rename

Severity: high
Time window: 1d
Group by: AccountDomain, AccountName, ActorUsername, AlgorithmCustomEntity, Commandline, DeviceName, DvcDomain, DvcHostname, DvcId, EventType, FileHashCustomEntity, FileName, FolderPath, Hash, InitiatingProcessFileName, InitiatingProcessId, InitiatingProcessSHA256, TargetFilePath, Type
Author: Microsoft Security Research
Source: github.com/Azure/Azure-Sentinel

Dev-0530 actors are known to encrypt the contents of the victims device as well as renaming the file extensions. This query looks for the creation of files with .h0lyenc extension or presence of ransom note.

MITRE ATT&CK coverage

Tactic	Techniques
Impact	`T1486` Data Encrypted for Impact

Event coverage

Provider	Event/ActionType	Title
Sysmon	Event ID 11	FileCreate
Security-Auditing	Event ID 4663	An attempt was made to access an object.
Defender-DeviceFileEvents	FileCreated	File created

Rule body kusto

id: d82eb796-d1eb-43c8-a813-325ce3417cef
name: Dev-0530 File Extension Rename
description: |
  'Dev-0530 actors are known to encrypt the contents of the victims device as well as renaming the file extensions. This query looks for the creation of files with .h0lyenc extension or presence of ransom note.'
severity: High
requiredDataConnectors:
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceFileEvents
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Impact
relevantTechniques:
  - T1486
tags:
  - Dev-0530
  - Schema: ASIMFileEvent
    SchemaVersion: 0.1.0
query: |
  union isfuzzy=true
      (DeviceFileEvents
      | where ActionType == "FileCreated"
      | where FileName endswith ".h0lyenc" or FolderPath == "C:\\FOR_DECRYPT.html"
      | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated)
          by
          AccountName = InitiatingProcessAccountName, AccountDomain = InitiatingProcessAccountDomain,
          DeviceName,
          Type,
          InitiatingProcessId,
          FileName,
          FolderPath,
          EventType = ActionType,
          Commandline = InitiatingProcessCommandLine,
          InitiatingProcessFileName,
          InitiatingProcessSHA256,
          FileHashCustomEntity = SHA256,
          AlgorithmCustomEntity = "SHA256"
      | extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
      | extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)
      ),
      (imFileEvent
      | where EventType == "FileCreated"
      | where TargetFilePath endswith ".h0lyenc" or TargetFilePath == "C:\\FOR_DECRYPT.html"
      | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated)
          by
          ActorUsername,
          DvcHostname,
          DvcDomain,
          DvcId,
          Type,
          EventType,
          FileHashCustomEntity = TargetFileSHA256,
          Hash,
          TargetFilePath,
          Commandline = ActingProcessCommandLine,
          AlgorithmCustomEntity = "SHA256"
      | extend AccountName = tostring(split(ActorUsername, @'\')[1]), AccountDomain = tostring(split(ActorUsername, @'\')[0])
      | extend HostName = DvcHostname, HostNameDomain = DvcDomain
      | extend DeviceName = strcat(DvcHostname, ".", DvcDomain )
      )
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: ActorUserName
      - identifier: Name
        columnName: AccountName
      - identifier: NTDomain
        columnName: AccountDomain
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
  - entityType: FileHash
    fieldMappings:
      - identifier: Algorithm
        columnName: AlgorithmCustomEntity
      - identifier: Value
        columnName: FileHashCustomEntity
version: 1.1.1
kind: Scheduled
metadata:
    source:
        kind: Community
    author:
        name: Microsoft Security Research
    support:
        tier: Community
    categories:
        domains: [ "Security - Others" ]

Stages and Predicates

union `isfuzzy=true` (2 sources)

Each leg below queries one source; the rule matches if any leg does. Sources: DeviceFileEvents, imFileEvent

Leg 1: `DeviceFileEvents`

DeviceFileEvents
    | where ActionType == "FileCreated"
    | where FileName endswith ".h0lyenc" or FolderPath == "C:\\FOR_DECRYPT.html"
    | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated)
        by
        AccountName = InitiatingProcessAccountName, AccountDomain = InitiatingProcessAccountDomain,
        DeviceName,
        Type,
        InitiatingProcessId,
        FileName,
        FolderPath,
        EventType = ActionType,
        Commandline = InitiatingProcessCommandLine,
        InitiatingProcessFileName,
        InitiatingProcessSHA256,
        FileHashCustomEntity = SHA256,
        AlgorithmCustomEntity = "SHA256"
    | extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
    | extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)

Leg 2: `imFileEvent`

imFileEvent
    | where EventType == "FileCreated"
    | where TargetFilePath endswith ".h0lyenc" or TargetFilePath == "C:\\FOR_DECRYPT.html"
    | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated)
        by
        ActorUsername,
        DvcHostname,
        DvcDomain,
        DvcId,
        Type,
        EventType,
        FileHashCustomEntity = TargetFileSHA256,
        Hash,
        TargetFilePath,
        Commandline = ActingProcessCommandLine,
        AlgorithmCustomEntity = "SHA256"
    | extend AccountName = tostring(split(ActorUsername, @'\')[1]), AccountDomain = tostring(split(ActorUsername, @'\')[0])
    | extend HostName = DvcHostname, HostNameDomain = DvcDomain
    | extend DeviceName = strcat(DvcHostname, ".", DvcDomain )

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	`FileCreated` transforms: `cased` corpus 8 (kusto 8)
`EventType`	eq	`FileCreated` transforms: `cased` corpus 8 (kusto 8)
`FileName`	ends_with	`.h0lyenc`
`FolderPath`	eq	`C:\\FOR_DECRYPT.html` transforms: `cased`
`TargetFilePath`	ends_with	`.h0lyenc`
`TargetFilePath`	eq	`C:\\FOR_DECRYPT.html` 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
`ActorUsername`	`summarize`
`AlgorithmCustomEntity`	`summarize`
`Commandline`	`summarize`
`DvcDomain`	`summarize`
`DvcHostname`	`summarize`
`DvcId`	`summarize`
`EndTime`	`summarize`
`EventType`	`summarize`
`FileHashCustomEntity`	`summarize`
`Hash`	`summarize`
`StartTime`	`summarize`
`TargetFilePath`	`summarize`
`Type`	`summarize`
`AccountDomain`	`extend`
`AccountName`	`extend`
`HostName`	`extend`
`HostNameDomain`	`extend`
`DeviceName`	`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)

Dev-0530 File Extension Rename

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

union `isfuzzy=true` (2 sources)

Leg 1: `DeviceFileEvents`

Leg 2: `imFileEvent`

Indicators

Output fields

Keyboard shortcuts

Search operators

Dev-0530 File Extension Rename

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

union isfuzzy=true (2 sources)

Leg 1: DeviceFileEvents

Leg 2: imFileEvent

Indicators

Output fields

union `isfuzzy=true` (2 sources)

Leg 1: `DeviceFileEvents`

Leg 2: `imFileEvent`