ADFS DKM Key Access

Severity: high
Type: alert
Time window: 5m
Match by: hostname
Source: github.com/chronicle/detection-rules

Detects access to the AD contact object to read the AD FS DKM (distributed key manager) master key value

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1552.004` Unsecured Credentials: Private Keys

References

https://github.com/OTRF/BHEU22-ADFS/blob/main/Slide-Deck.pdf

Event coverage

Provider	Event	Title
Security-Auditing	Event ID 4624	An account was successfully logged on.
Security-Auditing	Event ID 4625	An account failed to log on.
Security-Auditing	Event ID 4648	A logon was attempted using explicit credentials.
Security-Auditing	Event ID 4662	An operation was performed on an object.

Rule body yaral

/*
 * Copyright 2023 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

rule adfs_dkm_key_access {

  meta:
    author = "Google Cloud Security"
    description = "Detects access to the AD contact object to read the AD FS DKM (distributed key manager) master key value"
    rule_id = "mr_2517eaa0-0915-4a9e-8ca2-abce955eb635"
    rule_name = "ADFS DKM Key Access"
    reference = "https://github.com/OTRF/BHEU22-ADFS/blob/main/Slide-Deck.pdf"
    type = "alert"
    tactic = "TA0006"
    technique = "T1552.004"
    platform = "Windows"
    data_source = "windows security events"
    severity = "High"
    priority = "High"

  events:
    $object.metadata.event_type = "USER_RESOURCE_ACCESS"
    $object.metadata.product_name = "Microsoft-Windows-Security-Auditing"
    $object.metadata.vendor_name = "Microsoft"
    $object.metadata.product_event_type = "4662"
    any $object.security_result.detection_fields.value = "properties:{8d3bca50-1d7e-11d0-a081-00aa006c33ed}"
    $object.principal.labels["SubjectLogonId"] = $subject

    $login.metadata.event_type = "USER_LOGIN"
    $login.metadata.product_name = "Microsoft-Windows-Security-Auditing"
    $login.metadata.vendor_name = "Microsoft"
    $login.metadata.product_event_type = "4624"
    $login.target.labels["TargetLogonId"] = $subject
    $login.principal.hostname = $hostname

  match:
    $hostname over 5m

  outcome:
    $risk_score = 85
    //added to populate alert graph with additional context
    //Commented out because it is the same as the match variable, if match variable changes, uncomment to use
    //$principal_hostname = array_distinct($logon.principal.hostname)
    $object_principal_process_pid = array_distinct($object.principal.process.pid)
    $object_principal_user_userid = array_distinct($object.principal.user.userid)
    //$principal_user_windows_sid = array_distinct($object.principal.user.windows_sid)
    $object_target_resource_name = array_distinct($object.target.resource.name)

  condition:
    $object and $login
}

Stages and Predicates

Stage 0: `match + condition`

match:
    $hostname over 5m
condition:
    $object and $login

Fires when at least one $object event in the 5m window and at least one $login event in the 5m window.

Stage 1: `events: $login · USER_LOGIN`

$login.metadata.event_type = "USER_LOGIN"
$login.metadata.product_name = "Microsoft-Windows-Security-Auditing"
$login.metadata.vendor_name = "Microsoft"
$login.metadata.product_event_type = "4624"
$login.target.labels["TargetLogonId"] = $subject
$login.principal.hostname = $hostname

Stage 2: `events: $object · USER_RESOURCE_ACCESS`

$object.metadata.event_type = "USER_RESOURCE_ACCESS"
$object.metadata.product_name = "Microsoft-Windows-Security-Auditing"
$object.metadata.vendor_name = "Microsoft"
$object.metadata.product_event_type = "4662"
any $object.security_result.detection_fields.value = "properties:{8d3bca50-1d7e-11d0-a081-00aa006c33ed}"
$object.principal.labels["SubjectLogonId"] = $subject

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
`metadata.product_event_type`	eq	`4624` corpus 26 (splunk 13, kusto 9, chronicle 4) `4662` corpus 12 (splunk 7, kusto 4, chronicle 1)
`security_result.detection_fields.value`	eq	`properties:{8d3bca50-1d7e-11d0-a081-00aa006c33ed}` transforms: `existential`

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
`risk_score`	`85`
`object_principal_process_pid`	`array_distinct($object.principal.process.pid)`
`object_principal_user_userid`	`array_distinct($object.principal.user.userid)`
`object_target_resource_name`	`array_distinct($object.target.resource.name)`

`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:`)
`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)

ADFS DKM Key Access

MITRE ATT&CK coverage

References

Event coverage

Rule body yaral

Stages and Predicates

Stage 0: `match + condition`

Stage 1: `events: $login · USER_LOGIN`

Stage 2: `events: $object · USER_RESOURCE_ACCESS`

Indicators

Output fields

Keyboard shortcuts

Search operators

ADFS DKM Key Access

MITRE ATT&CK coverage

References

Event coverage

Rule body yaral

Stages and Predicates

Stage 0: match + condition

Stage 1: events: $login · USER_LOGIN

Stage 2: events: $object · USER_RESOURCE_ACCESS

Indicators

Output fields

Stage 0: `match + condition`

Stage 1: `events: $login · USER_LOGIN`

Stage 2: `events: $object · USER_RESOURCE_ACCESS`