# T1499 - Endpoint Denial of Service

## SOC Recommendation
Investigate Endpoint Denial of Service activity in the context of Impact: confirm scope, affected host/identity, and whether it matches expected administrative behaviour before deciding this is benign.

## D3FEND Mappings
| D3FEND Technique | Relationship | Practical SOC Action |
|---|---|---|
| User Geolocation Logon Pattern Analysis | Detect | Monitor for User Geolocation Logon Pattern Analysis indicators relevant to this technique. |
| Network Traffic Filtering | Isolate | Apply Network Traffic Filtering to contain the blast radius once this technique is observed. |

## Investigation Steps
1. Confirm matching entities (user, host, IP) and validate data freshness in the lookback period.
2. Check whether activity aligns with a planned change or approved business process.
3. Identify all affected users/devices/resources over the prior 24 hours.
4. Determine whether this is isolated or part of a broader campaign.
5. Correlate with identity, endpoint, and email/cloud telemetry for related suspicious actions.
6. Elevate severity if privileged identities, critical systems, or repeated activity is observed.
7. Capture all evidence (query results, entities, timeline) in the incident record.
8. Route to the appropriate response playbook and customer escalation path.

## Evidence to Collect
- Host or resource affected
- Account or identity involved
- Timestamp of the activity
- Related process, file, or network artifact
- Any preceding or follow-on alerts

## Response Actions
| Action | Risk | Automation Safe | Approval Required |
|---|---|---|---|
| Contain impacted identities/endpoints/sessions based on obse | Low | No | Yes |
| Block malicious indicators (IP, URL, domain, hash) where ava | Medium | No | Yes |
| Complete blast radius analysis across related logs and entit | Low | No | Yes |
| Notify stakeholders according to incident priority and custo | Low | Yes | No |
| Remove persistence or unauthorized access paths identified d | Low | No | Yes |
| Capture lessons learned and update rule tuning/watchlists. | Low | No | Yes |

## KQL
```kql
let query_frequency = 15m;
let missing_period = 1h;
//Enter a reference list of hostnames for your DC servers
let DCServersList = dynamic (["DC01.simulandlabs.com","DC02.simulandlabs.com"]);
//Alternatively, a Watchlist can be used
//let DCServersList = _GetWatchlist('HostName-DomainControllers') | project HostName;
Heartbeat
| summarize arg_max(TimeGenerated, *) by Computer
| where Computer in (DCServersList)
//You may specify the OS type of your Domain Controllers
//| where OSType == 'Windows'
| where TimeGenerated between (ago(query_frequency + missing_period) .. ago(missing_period))
| project TimeGenerated, Computer, OSType, Version, ComputerEnvironment, Type, Solutions
| sort by TimeGenerated asc
```
```kql
let timeframe = 1h;
CrowdStrikeFalconEventStream
| where TimeGenerated > ago(timeframe)
| where EventType == "DetectionSummaryEvent"
| where Severity == "Critical"
| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), Total = count() by DstHostName, SrcIpAddr, DstUserName, Activity, Technique, FileName, FilePath, FileHash, Message
| extend timestamp = StartTimeUtc, AccountCustomEntity = DstUserName, HostCustomEntity = DstHostName, IPCustomEntity = SrcIpAddr, FileHashCustomEntity = FileHash, FileHashAlgo = "MD5"
| project StartTimeUtc, EndTimeUtc, Total, DstHostName, SrcIpAddr, DstUserName, Activity, Technique, FileName, FilePath, FileHash, Message, timestamp, AccountCustomEntity, HostCustomEntity, IPCustomEntity, FileHashCustomEntity, FileHashAlgo
```
```kql
// High Severity Domain/IP Vulnerability Exposure Detected
let timeFrame = 5m;
CyfirmaASDomainIPVulnerabilityAlerts_CL
| where severity == 'Critical' and TimeGenerated between (ago(timeFrame) .. now())
| mv-expand pvuln = possible_vulnerabilities
| extend cve = tostring(pvuln.cveNo), vulProducts = pvuln.products
| mv-expand vul_Products = vulProducts
| summarize cveList = make_set(cve, 100), vul_products1 = make_set(vul_Products, 100)    by uid
| join kind=inner (CyfirmaASDomainIPVulnerabilityAlerts_CL
    | where severity == 'Critical'
    | summarize arg_max(TimeGenerated, *) by uid)
    on uid
| extend
    Vulnerabilities = strcat_array(cveList, ', '),
    VulnerabilityProducts = strcat_array(vul_products1, ', '),
    Description=description,
    FirstSeen=first_seen,
    LastSeen=last_seen,
    RiskScore=risk_score,
    Domain=sub_domain,
    TopDomain=top_domain,
    NetworkIP=ip,
    AlertUID=alert_uid,
    UID=uid,
    OpenPorts=open_ports,
    HostProvider=host_provider,
    Country=country,
    Softwares=softwares,
    WebServer=web_server,
    WebServerVersion=web_server_version,
    ProviderName='CYFIRMA',
    ProductName='DeCYFIR/DeTCT'
| project
    TimeGenerated,
    Description,
    Domain,
    TopDomain,
    RiskScore,
    FirstSeen,
    LastSeen,
    NetworkIP,
    AlertUID,
    UID,
    Vulnerabilities,
    VulnerabilityProducts,
    OpenPorts,
    HostProvider,
    Country,
    Softwares,
    WebServer,
    WebServerVersion,
    ProviderName,
    ProductName
```

## Escalation Criteria
- Endpoint Denial of Service activity observed on a privileged account or critical system.
- Activity follows or precedes other suspicious behaviour in the same investigation.
- Automated triage cannot confidently rule out malicious intent.

## False Positive Considerations
- Legitimate admin or business workflow — Activity maps to approved change tickets or known process owners
- Security testing or red-team exercise — Source identity/host matches approved test plan

Generated by SOC Response Atlas by Basyrix.