Shadow Credentials Added to Account

Author: FalconForce
Source: github.com/FalconForceTeam/FalconFriday

This query searches for modifications to the 'msDS-KeyCredentialLink' property in Active Directory, introduced in Windows Server 2016. There are two different events which contain information to detect such changes 5136 and 4662. This detection uses the 5136, which is the preferred event to use.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1098` Account Manipulation
Privilege Escalation	`T1098` Account Manipulation, `T1484` Domain or Tenant Policy Modification

References

Event coverage

Provider	Event	Title
Security-Auditing	Event ID 5136	A directory service object was modified.

Rule body kusto

let timeframe = 2*1h;
let RuleId = "0275";
let DedupFields = dynamic(["TimeGenerated", "SubjectUserName", "Computer"]);
SecurityEvent
| where ingestion_time() >= ago(timeframe)
| where EventID == 5136
| extend AttributeName = extract("<Data Name=\"AttributeLDAPDisplayName\">(.*?)</Data>", 1, EventData)
| extend ObjectDN = extract("<Data Name=\"ObjectDN\">(.*?)</Data>", 1, EventData)
| extend SubjectUserName = extract("<Data Name=\"SubjectUserName\">(.*?)</Data>", 1, EventData)
| where AttributeName has "msDS-KeyCredentialLink"
| where not(SubjectUserName endswith "$" and ObjectDN startswith strcat("CN=", replace_string(SubjectUserName, "$", ""), ",")) // Machine account changing its own msDS-KeyCredentialLink.
| extend HostName=tostring(split(Computer,".")[0]),DnsDomain=iif(Computer contains ".", substring(Computer, indexof(Computer, ".") + 1, strlen(Computer)),"")
| extend AccountName=iif(Account contains @"\",tostring(split(Account,@"\")[1]),Account),AccountDomain=iif(Account contains @"\",tostring(split(Account,@"\")[0]),"")
// Begin environment-specific filter.
// End environment-specific filter.
// Begin de-duplication logic.
| extend DedupFieldValues=pack_all()
| mv-apply e=DedupFields to typeof(string) on (
    extend DedupValue=DedupFieldValues[tostring(e)]
    | order by e // Sorting is required to ensure make_list is deterministic.
    | summarize DedupValues=make_list(DedupValue)
)
| extend DedupEntity=strcat_array(DedupValues, "|")
| project-away DedupFieldValues, DedupValues
| join kind=leftanti (
    SecurityAlert
    | where AlertName has RuleId and ProviderName has "ASI"
    | where TimeGenerated >= ago(timeframe)
    | extend DedupEntity = tostring(parse_json(tostring(parse_json(ExtendedProperties)["Custom Details"])).DedupEntity[0])
    | project DedupEntity
) on DedupEntity
// End de-duplication logic.

Stages and Predicates

Parameters

let timeframe = 2*1h;
let RuleId = "0275";
let DedupFields = dynamic(["TimeGenerated", "SubjectUserName", "Computer"]);

Stage 1: `source`

SecurityEvent

Stage 2: `where`

| where ingestion_time() >= ago(timeframe)

Stage 3: `where`

| where EventID == 5136

Stage 4: `extend` (3 consecutive steps)

| extend AttributeName = extract("<Data Name=\"AttributeLDAPDisplayName\">(.*?)</Data>", 1, EventData)
| extend ObjectDN = extract("<Data Name=\"ObjectDN\">(.*?)</Data>", 1, EventData)
| extend SubjectUserName = extract("<Data Name=\"SubjectUserName\">(.*?)</Data>", 1, EventData)

Stage 5: `where`

| where AttributeName has "msDS-KeyCredentialLink"

Stage 6: `where`

| where not(SubjectUserName endswith "$" and ObjectDN startswith strcat("CN=", replace_string(SubjectUserName, "$", ""), ","))

Stage 7: `extend` (3 consecutive steps)

| extend HostName=tostring(split(Computer,".")[0]),DnsDomain=iif(Computer contains ".", substring(Computer, indexof(Computer, ".") + 1, strlen(Computer)),"")
| extend AccountName=iif(Account contains @"\",tostring(split(Account,@"\")[1]),Account),AccountDomain=iif(Account contains @"\",tostring(split(Account,@"\")[0]),"")
| extend DedupFieldValues=pack_all()

Stage 8: `kusto:mv-apply`

| mv-apply e=DedupFields to typeof(string) on (
    extend DedupValue=DedupFieldValues[tostring(e)]
    | order by e
    | summarize DedupValues=make_list(DedupValue)
)

Stage 9: `extend`

| extend DedupEntity=strcat_array(DedupValues, "|")

Stage 10: `project-away`

| project-away DedupFieldValues, DedupValues

Stage 11: `join` (negated)

| join kind=leftanti (
    SecurityAlert
    | where AlertName has RuleId and ProviderName has "ASI"
    | where TimeGenerated >= ago(timeframe)
    | extend DedupEntity = tostring(parse_json(tostring(parse_json(ExtendedProperties)["Custom Details"])).DedupEntity[0])
    | project DedupEntity
) on DedupEntity

Stage 12: `summarize`

summarize

Exclusions

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

Field	Kind	Excluded values
`SubjectUserName`	ends_with	`$`
`AlertName`	match	`0275`
`ProviderName`	match	`ASI`

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
`AttributeName`	match	`msDS-KeyCredentialLink` transforms: `term`
`EventID`	eq	`5136` transforms: `cased` corpus 30 (splunk 24, kusto 5, elastic 1)

`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)

Shadow Credentials Added to Account

MITRE ATT&CK coverage

References

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend` (3 consecutive steps)

Stage 5: `where`

Stage 6: `where`

Stage 7: `extend` (3 consecutive steps)

Stage 8: `kusto:mv-apply`

Stage 9: `extend`

Stage 10: `project-away`

Stage 11: `join` (negated)

Stage 12: `summarize`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Shadow Credentials Added to Account

MITRE ATT&CK coverage

References

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: extend (3 consecutive steps)

Stage 5: where

Stage 6: where

Stage 7: extend (3 consecutive steps)

Stage 8: kusto:mv-apply

Stage 9: extend

Stage 10: project-away

Stage 11: join (negated)

Stage 12: summarize

Exclusions

Indicators

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend` (3 consecutive steps)

Stage 5: `where`

Stage 6: `where`

Stage 7: `extend` (3 consecutive steps)

Stage 8: `kusto:mv-apply`

Stage 9: `extend`

Stage 10: `project-away`

Stage 11: `join` (negated)

Stage 12: `summarize`