Microsoft COVID-19 file hash indicator matches

Status: available
Severity: medium
Time window: 14d
Group by: FileHash, FileHashValue
Source: github.com/Azure/Azure-Sentinel

'Identifies a match in CommonSecurityLog Event data from any FileHash published in the Microsoft COVID-19 Threat Intel Feed - as described at https://www.microsoft.com/security/blog/2020/05/14/open-sourcing-covid-threat-intelligence/'

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1204.002` User Execution: Malicious File

Rule body kusto

id: 2be4ef67-a93f-4d8a-981a-88158cb73abd
name: Microsoft COVID-19 file hash indicator matches
description: |
  'Identifies a match in CommonSecurityLog Event data from any FileHash published in the Microsoft COVID-19 Threat Intel Feed - as described at https://www.microsoft.com/security/blog/2020/05/14/open-sourcing-covid-threat-intelligence/'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: CefAma
    dataTypes:
      - CommonSecurityLog
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Execution
relevantTechniques:
  - T1204.002
query: |
  let dt_lookBack = 1h;
  let covidIndicators = (externaldata(TimeGenerated:datetime, FileHashValue:string, FileHashType: string, TlpLevel: string, Product: string, ThreatType: string, Description: string )
  [@"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/Microsoft.Covid19.Indicators.csv"] with (format="csv"));
  let fileHashIndicators = covidIndicators
  | where isnotempty(FileHashValue);
  // Handle matches against both lower case and uppercase versions of the hash:
  (fileHashIndicators | extend FileHashValue = tolower(FileHashValue)
  | union (fileHashIndicators | extend FileHashValue = toupper(FileHashValue)))
  // using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
  |  join kind=innerunique (
     CommonSecurityLog | where TimeGenerated >= ago(dt_lookBack)
     | where isnotempty(FileHash)
     | extend CommonSecurityLog_TimeGenerated = TimeGenerated
     )
  on $left.FileHashValue == $right.FileHash
  | summarize CommonSecurityLog_TimeGenerated = arg_max(CommonSecurityLog_TimeGenerated, *) by FileHashValue
  | project CommonSecurityLog_TimeGenerated, FileHashValue, FileHashType, Description, ThreatType,
  SourceIP, SourcePort, DestinationIP, DestinationPort, SourceUserID, SourceUserName, DeviceName, DeviceAction,
  RequestURL, DestinationUserName, DestinationUserID, ApplicationProtocol, Activity
  | extend AccountName = tostring(split(SourceUserName, "@")[0]), AccountUPNSuffix = tostring(split(SourceUserName, "@")[1])
  | 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: SourceUserName
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: AccountUPNSuffix
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIP
  - entityType: FileHash
    fieldMappings:
      - identifier: Value
        columnName: FileHashValue
      - identifier: Algorithm
        columnName: FileHashType
version: 1.3.6
kind: Scheduled

Stages and Predicates

Parameters

let dt_lookBack = 1h;

Let binding: `covidIndicators`

let covidIndicators = (externaldata(TimeGenerated:datetime, FileHashValue:string, FileHashType: string, TlpLevel: string, Product: string, ThreatType: string, Description: string )
[@"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/Microsoft.Covid19.Indicators.csv"] with (format="csv"));

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

Stage 1: `source`

covidIndicators

Stage 2: `where`

| where isnotempty(FileHashValue)

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

Stage 3: `extend`

fileHashIndicators
| extend FileHashValue = tolower(FileHashValue)

Stage 4: `union`

| union

Stage 5: `source`

covidIndicators

Stage 6: `where`

| where isnotempty(FileHashValue)

Stage 7: `extend`

| extend FileHashValue = toupper(FileHashValue)

Stage 8: `join`

| join kind=innerunique (
   CommonSecurityLog | where TimeGenerated >= ago(dt_lookBack)
   | where isnotempty(FileHash)
   | extend CommonSecurityLog_TimeGenerated = TimeGenerated
   )
on $left.FileHashValue == $right.FileHash

Stage 9: `summarize`

| summarize CommonSecurityLog_TimeGenerated = arg_max(CommonSecurityLog_TimeGenerated, *) by FileHashValue

Stage 10: `project`

| project CommonSecurityLog_TimeGenerated, FileHashValue, FileHashType, Description, ThreatType,
SourceIP, SourcePort, DestinationIP, DestinationPort, SourceUserID, SourceUserName, DeviceName, DeviceAction,
RequestURL, DestinationUserName, DestinationUserID, ApplicationProtocol, Activity

Stage 11: `extend` (3 consecutive steps)

| extend AccountName = tostring(split(SourceUserName, "@")[0]), AccountUPNSuffix = tostring(split(SourceUserName, "@")[1])
| 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
`FileHash`	is_not_null	(no value, null check)
`FileHashValue`	is_not_null	(no value, null check)

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
`Activity`	`project`
`ApplicationProtocol`	`project`
`CommonSecurityLog_TimeGenerated`	`project`
`Description`	`project`
`DestinationIP`	`project`
`DestinationPort`	`project`
`DestinationUserID`	`project`
`DestinationUserName`	`project`
`DeviceAction`	`project`
`DeviceName`	`project`
`FileHashType`	`project`
`FileHashValue`	`project`
`RequestURL`	`project`
`SourceIP`	`project`
`SourcePort`	`project`
`SourceUserID`	`project`
`SourceUserName`	`project`
`ThreatType`	`project`
`AccountName`	`extend`
`AccountUPNSuffix`	`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)

Microsoft COVID-19 file hash indicator matches

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: `covidIndicators`

Stage 1: `source`

Stage 2: `where`

Stage 3: `extend`

Stage 4: `union`

Stage 5: `source`

Stage 6: `where`

Stage 7: `extend`

Stage 8: `join`

Stage 9: `summarize`

Stage 10: `project`

Stage 11: `extend` (3 consecutive steps)

Indicators

Output fields

Keyboard shortcuts

Search operators

Microsoft COVID-19 file hash indicator matches

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: covidIndicators

Stage 1: source

Stage 2: where

Stage 3: extend

Stage 4: union

Stage 5: source

Stage 6: where

Stage 7: extend

Stage 8: join

Stage 9: summarize

Stage 10: project

Stage 11: extend (3 consecutive steps)

Indicators

Output fields

Let binding: `covidIndicators`

Stage 1: `source`

Stage 2: `where`

Stage 3: `extend`

Stage 4: `union`

Stage 5: `source`

Stage 6: `where`

Stage 7: `extend`

Stage 8: `join`

Stage 9: `summarize`

Stage 10: `project`

Stage 11: `extend` (3 consecutive steps)