Crowdstrike Single IP Allowlisted

Severity: medium
Log types: Crowdstrike.EventStreams
Source: github.com/panther-labs/panther-analysis

A single IP (instead of a CIDR range) was allowlisted. This could indicate a bad actor permitting access from another machine.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1556.009` Modify Authentication Process: Conditional Access Policies
Credential Access	`T1556.009` Modify Authentication Process: Conditional Access Policies

Rule body yaml

AnalysisType: rule
Filename: crowdstrike_single_ip_allowlisted.py
RuleID: "Crowdstrike.SingleIpAllowlisted"
DisplayName: "Crowdstrike Single IP Allowlisted"
Enabled: true
LogTypes:
  - Crowdstrike.EventStreams
Severity: Medium
Reports:
  MITRE ATT&CK:
    - TA0003:T1556.009 # Persistsnce: Modify Authentication Process: Conditional Access Policies
    - TA0005:T1556.009 # Defense Evasion: Modify Authentication Process: Conditional Access Policies
    - TA0006:T1556.009 # Credential Access: Modify Authentication Process: Conditional Access Policies
Description: A single IP (instead of a CIDR range) was allowlisted. This could indicate a bad actor permitting access from another machine.
DedupPeriodMinutes: 60
Threshold: 1
Runbook: Validate this action was authorized, and determine the client to which the IP belongs to.
Tests:
  - Name: A Single IP In Created Allowlist
    ExpectedResult: true
    Log:
      {
        "event": {
          "AuditKeyValues": [
            {
              "Key": "allowlist_group_id",
              "ValueString": "24821376-7e77-431e-9469-74846978fe64"
            },
            {
              "Key": "group_name",
              "ValueString": "example_group"
            },
            {
              "Key": "description",
              "ValueString": ""
            },
            {
              "Key": "cidrs",
              "ValueString": "[1.1.1.1]"
            },
            {
              "Key": "contexts",
              "ValueString": "[API]"
            },
            {
              "Key": "active",
              "ValueString": "false"
            }
          ],
          "OperationName": "CreateAllowlistGroup",
          "ServiceName": "Crowdstrike Allowlist Management",
          "Success": true,
          "UTCTimestamp": "2024-07-26 16:13:13.000000000",
          "UserId": "wormtongue@isengard.org",
          "UserIp": "1.2.3.4"
        },
        "metadata": {
          "customerIDString": "fake_cust_id",
          "eventCreationTime": "2024-07-26 16:13:13.579000000",
          "eventType": "AuthActivityAuditEvent",
          "offset": 365164,
          "version": "1.0"
        }
      }
  - Name: Multiple Single IPs In Created Allowlist
    ExpectedResult: true
    Log:
      {
        "event": {
          "AuditKeyValues": [
            {
              "Key": "allowlist_group_id",
              "ValueString": "24821376-7e77-431e-9469-74846978fe64"
            },
            {
              "Key": "group_name",
              "ValueString": "example_group"
            },
            {
              "Key": "description",
              "ValueString": ""
            },
            {
              "Key": "cidrs",
              "ValueString": "[1.1.1.1 2.2.2.2 3.3.3.3/32]"
            },
            {
              "Key": "contexts",
              "ValueString": "[API UI OTHER]"
            },
            {
              "Key": "active",
              "ValueString": "false"
            }
          ],
          "OperationName": "CreateAllowlistGroup",
          "ServiceName": "Crowdstrike Allowlist Management",
          "Success": true,
          "UTCTimestamp": "2024-07-26 16:13:13.000000000",
          "UserId": "wormtongue@isengard.org",
          "UserIp": "1.2.3.4"
        },
        "metadata": {
          "customerIDString": "fake_cust_id",
          "eventCreationTime": "2024-07-26 16:13:13.579000000",
          "eventType": "AuthActivityAuditEvent",
          "offset": 365164,
          "version": "1.0"
        }
      }
  - Name: Single IP Added to existing Allowlist
    ExpectedResult: true
    Log:
      {
        "event": {
          "AuditKeyValues": [
            {
              "Key": "old_group_name",
              "ValueString": "my_allowlist"
            },
            {
              "Key": "old_cidrs",
              "ValueString": "[1.2.3.4/8]"
            },
            {
              "Key": "allowlist_group_id",
              "ValueString": "24821376-7e77-431e-9469-74846978fe64"
            },
            {
              "Key": "group_name",
              "ValueString": "my_allowlist"
            },
            {
              "Key": "description",
              "ValueString": ""
            },
            {
              "Key": "cidrs",
              "ValueString": "[1.2.3.4/8 32.32.32.32]"
            },
            {
              "Key": "contexts",
              "ValueString": "[API]"
            },
            {
              "Key": "active",
              "ValueString": "false"
            },
            {
              "Key": "old_allowlist_group_id",
              "ValueString": "24821376-7e77-431e-9469-74846978fe64"
            },
            {
              "Key": "old_description",
              "ValueString": ""
            },
            {
              "Key": "old_contexts",
              "ValueString": "[API]"
            },
            {
              "Key": "old_active",
              "ValueString": "false"
            }
          ],
          "OperationName": "UpdateAllowlistGroup",
          "ServiceName": "Crowdstrike Allowlist Management",
          "Success": true,
          "UTCTimestamp": "2024-07-26 19:47:16.000000000",
          "UserId": "wormtongue@isengard.org",
          "UserIp": "1.2.3.4"
        },
        "metadata": {
          "customerIDString": "fake_customer_id",
          "eventCreationTime": "2024-07-26 19:47:16.428000000",
          "eventType": "AuthActivityAuditEvent",
          "offset": 366148,
          "version": "1.0"
        }
      }
  - Name: Only CIDR Ranges In Created Allowlist
    ExpectedResult: false
    Log:
      {
        "event": {
          "AuditKeyValues": [
            {
              "Key": "allowlist_group_id",
              "ValueString": "24821376-7e77-431e-9469-74846978fe64"
            },
            {
              "Key": "group_name",
              "ValueString": "example_group"
            },
            {
              "Key": "description",
              "ValueString": ""
            },
            {
              "Key": "cidrs",
              "ValueString": "[1.1.1.1/12 2.2.2.2/8 3.3.3.3/4]"
            },
            {
              "Key": "contexts",
              "ValueString": "[API UI OTHER]"
            },
            {
              "Key": "active",
              "ValueString": "false"
            }
          ],
          "OperationName": "CreateAllowlistGroup",
          "ServiceName": "Crowdstrike Allowlist Management",
          "Success": true,
          "UTCTimestamp": "2024-07-26 16:13:13.000000000",
          "UserId": "wormtongue@isengard.org",
          "UserIp": "1.2.3.4"
        },
        "metadata": {
          "customerIDString": "fake_cust_id",
          "eventCreationTime": "2024-07-26 16:13:13.579000000",
          "eventType": "AuthActivityAuditEvent",
          "offset": 365164,
          "version": "1.0"
        }
      }
  - Name: Unrelated Event
    ExpectedResult: false
    Log:
      {
        "metadata": {
          "customerIDString": "fake_customer_id",
          "offset": 341329,
          "eventType": "AuthActivityAuditEvent",
          "eventCreationTime": "2024-07-22 15:50:16.923000000",
          "version": "1.0"
        },
        "event": {
          "UserId": "sharkey@hobbiton.co",
          "UserIp": "192.0.2.100",
          "OperationName": "deleteUser",
          "ServiceName": "CrowdStrike Authentication",
          "Success": true,
          "UTCTimestamp": "2024-07-22 15:50:16.923000000",
          "AuditKeyValues": [
            {
              "Key": "target_name",
              "ValueString": "frodo.baggins@hobbiton.co"
            }
          ]
        }
      }

Detection logic

Condition

event.OperationName in ["CreateAllowlistGroup", "UpdateAllowlistGroup"]

This rule also runs imperative logic the parser cannot express as a filter; the conditions above are the structured part it could extract.

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
`event.OperationName`	in	`CreateAllowlistGroup` `UpdateAllowlistGroup`

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
`UserId`	`event.UserId`

`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)