Incident: Failed logon burst followed by successful authentication (+1 related finding)

Case: CASE-001
Generated: 2026-09-26 11:07:33 UTC
Status: complete
Severity: CRITICAL
Grouping confidence: medium (how strongly findings are linked, not whether an intrusion occurred)
Hosts: WS-2138, WS-9673
Accounts: acct-2520
Window: 2026-08-01 08:00:00 -> 08:06:00 UTC (360s)
Telemetry: generated_auth_execution

This report was produced by an automated investigation. It presents evidence-backed findings for analyst review and does not authorise or perform any response action.

Verdict

Disposition: Malicious
Decided by: deterministic triage of the seed findings
Engine: deterministic
Profile: operational-v6
Model: none (deterministic engine)
Evidence basis: 30 typed observation(s) checked against recorded telemetry; 0 claim(s) rejected by verification; 3 specialist step(s) run (endpoint, identity, attack); 8 tool call(s) served, 0 refused.
Supporting event ids: none cited by the concluding explanations

This system does not compute a confidence score for its verdict. The evidence basis is a count of what was checked, not a measure of how likely the verdict is.

Investigation Tree

Initial alert: Failed logon burst followed by successful authentication (+1 related finding)
rules ATH-005, ATH-007; 14 seed event(s): 0adbb9ef85b9188c8683, 0cb61159ea3d69dcc87a, 0cc680d6694f1f8615a1, 2108af7a380995a548b5, 3bdd60cc3a5a97b84519, 67a9f5bfab28871757dd, +8 more
↓
ATH investigation (engine deterministic)
- endpoint
  why deterministic priority order; case evidence rests on process_command_line, process_execution, process_lineage telemetry (from ATH-007)
  tools get_events, get_events, process_tree
  new events 2 retrieved; shown: 98c80712635dec2f3738, 0b092d00f3798939dd00
- identity
  why deterministic priority order; case evidence rests on auth_source_attribution, authentication telemetry (from ATH-005)
  tools user_auth_history
  new events 12 retrieved; shown: 0ce208dd57c057228f55, 8144033a5e9cd2c19c38, 78274bf69ec1ff508093, c532eb018e1154acca2e, 7c156d83425329cf030a, 0d4ac76c0560bdbb704b, +6 more
- attack
  why only eligible specialist; case has ATT&CK mappings and domain evidence has been gathered
  tools lookup_technique, lookup_technique, lookup_technique, lookup_technique
- evidence_verifier
  why validate typed observations against cited telemetry
stopped: no specialist has further useful work on the available evidence
↓
Verdict: Malicious

Reasoning Summary

No model-written reasoning: this run used no model. Its reasoning is the specialist trace in the investigation tree and the findings below.

Executive Summary

This report covers CASE-001, correlating 2 detection finding(s) across 2 host(s) (WS-2138, WS-9673) and 1 account(s) (acct-2520) between 08:00:00 and 08:06:00 UTC on 2026-08-01. The evidence is consistent with activity spanning 4 MITRE ATT&CK tactic(s): Execution -> Persistence -> Credential Access -> Lateral Movement. Each mapping is an interpretation of observed behaviour against a public taxonomy, not a determination that an intrusion occurred. 30 statement(s) below are directly established by telemetry, 11 are evidence-supported inferences, and 0 are explicitly unverified hypotheses requiring analyst confirmation. This report does not authorise or perform any response action. All recommendations below require human review before action is taken.

Attack Timeline

Time	Rule	Severity	User	Host / Movement	ATT&CK	Events
08:00:00	ATH-005	CRITICAL	acct-2520	WS-9673	T1078, T1110.001	`0cb61159ea3d69dcc87a`, `d92873fb243f9f0bcb0d`, `3bdd60cc3a5a97b84519`, `a068ff51cd2cb23d2f8d`, `2108af7a380995a548b5`, `6e10a5cc29314bc6a964`, +7 more
08:06:00	ATH-007	HIGH	acct-2520	WS-9673	T1021.002, T1569.002	`c1aa4d45ddf2102946f7`

Findings

Confirmed (FACT) (30)

Confirmed: Authentication event 0adbb9ef85b9188c8683 records outcome failure.
Evidence: 0adbb9ef85b9188c8683
Confirmed: Event 0b092d00f3798939dd00 records process identity sysmon:399d50933db741bad79daec0f397fe8d.
Evidence: 0b092d00f3798939dd00
Confirmed: Authentication event 0cb61159ea3d69dcc87a records outcome failure.
Evidence: 0cb61159ea3d69dcc87a
Confirmed: Authentication event 0cc680d6694f1f8615a1 records outcome failure.
Evidence: 0cc680d6694f1f8615a1
Confirmed: Authentication event 0ce208dd57c057228f55 records outcome success.
Evidence: 0ce208dd57c057228f55
Confirmed: Authentication event 0d4ac76c0560bdbb704b records outcome success.
Evidence: 0d4ac76c0560bdbb704b
Confirmed: Authentication event 2108af7a380995a548b5 records outcome failure.
Evidence: 2108af7a380995a548b5
Confirmed: Authentication event 3bdd60cc3a5a97b84519 records outcome failure.
Evidence: 3bdd60cc3a5a97b84519
Confirmed: Authentication event 5c0abbbce84e1b2a43fa records outcome success.
Evidence: 5c0abbbce84e1b2a43fa
Confirmed: Authentication event 67a9f5bfab28871757dd records outcome success.
Evidence: 67a9f5bfab28871757dd
Confirmed: Authentication event 6e10a5cc29314bc6a964 records outcome failure.
Evidence: 6e10a5cc29314bc6a964
Confirmed: Authentication event 78274bf69ec1ff508093 records outcome success.
Evidence: 78274bf69ec1ff508093
Confirmed: Authentication event 7c156d83425329cf030a records outcome success.
Evidence: 7c156d83425329cf030a
Confirmed: Authentication event 8144033a5e9cd2c19c38 records outcome success.
Evidence: 8144033a5e9cd2c19c38
Confirmed: Authentication event 8407329aafd15d9c0a9e records outcome failure.
Evidence: 8407329aafd15d9c0a9e
Confirmed: Event 98c80712635dec2f3738 records process identity sysmon:b06bb26c2e219a238c5b67fc124fd6ea.
Evidence: 98c80712635dec2f3738
Confirmed: Authentication event 9ad22469dab49a3df6fc records outcome success.
Evidence: 9ad22469dab49a3df6fc
Confirmed: Authentication event 9b73d640145c27f1eddb records outcome success.
Evidence: 9b73d640145c27f1eddb
Confirmed: Authentication event a068ff51cd2cb23d2f8d records outcome failure.
Evidence: a068ff51cd2cb23d2f8d
Confirmed: Authentication event a3bf61cc981c8d0cdd5d records outcome failure.
Evidence: a3bf61cc981c8d0cdd5d
Confirmed: Authentication event bc5bc87bcd4bf9827807 records outcome failure.
Evidence: bc5bc87bcd4bf9827807
Confirmed: Event c1aa4d45ddf2102946f7 records process identity sysmon:ffa91f20286f6ae3e86e4b01e0c39444.
Evidence: c1aa4d45ddf2102946f7
Confirmed: Authentication event c532eb018e1154acca2e records outcome success.
Evidence: c532eb018e1154acca2e
Confirmed: Authentication event d92873fb243f9f0bcb0d records outcome failure.
Evidence: d92873fb243f9f0bcb0d
Confirmed: Authentication event dfd20d6fe31907ff2b86 records outcome success.
Evidence: dfd20d6fe31907ff2b86
Confirmed: Authentication event e5a3cce5c1c4a821f59d records outcome success.
Evidence: e5a3cce5c1c4a821f59d
Confirmed: Authentication event f6497a719ee487d49e5a records outcome failure.
Evidence: f6497a719ee487d49e5a
Confirmed: Authentication event fbe91286e9d9acc93b9e records outcome success.
Evidence: fbe91286e9d9acc93b9e
Confirmed: Process event 0b092d00f3798939dd00 identifies the instance in c1aa4d45ddf2102946f7 as its parent.
Evidence: c1aa4d45ddf2102946f7, 0b092d00f3798939dd00
Confirmed: Process event c1aa4d45ddf2102946f7 identifies the instance in 98c80712635dec2f3738 as its parent.
Evidence: 98c80712635dec2f3738, c1aa4d45ddf2102946f7

Assessed (INFERENCE) (11)

Assessed: Unverified summary: On WS-9673, cmd.exe (PID 500) was started by services.exe under account acct-2520.
Evidence: c1aa4d45ddf2102946f7
Assessed: Unverified summary: Execution chain on WS-9673: wininit.exe -> services.exe -> cmd.exe.
Evidence: c1aa4d45ddf2102946f7, 98c80712635dec2f3738
Assessed: Unverified summary: cmd.exe (PID 500) on WS-9673 spawned 1 child process(es): dism.exe.
Evidence: 0b092d00f3798939dd00
Assessed: Unverified summary: Account 'acct-2520' has 25 authentication events (12 failed, 13 successful) across hosts OFFICE-01, WS-9673.
Evidence: 0ce208dd57c057228f55, 0cb61159ea3d69dcc87a, d92873fb243f9f0bcb0d, 8144033a5e9cd2c19c38, 3bdd60cc3a5a97b84519, 78274bf69ec1ff508093, +19 more
Assessed: Unverified summary: Account 'acct-2520' authenticated from more than one source host: OFFICE-01, WS-2138.
Evidence: 0ce208dd57c057228f55, 0cb61159ea3d69dcc87a, d92873fb243f9f0bcb0d, 8144033a5e9cd2c19c38, 3bdd60cc3a5a97b84519, 78274bf69ec1ff508093, +19 more
Assessed: The 12 failed authentications for 'acct-2520' followed by success are consistent with the account's password having been guessed rather than with ordinary user error. (confidence 0.85)
Evidence: 0cb61159ea3d69dcc87a, d92873fb243f9f0bcb0d, 3bdd60cc3a5a97b84519, a068ff51cd2cb23d2f8d, 2108af7a380995a548b5, 6e10a5cc29314bc6a964, +6 more
Assessed: Behaviour cited by ATH-005 is consistent with T1110.001 Brute Force: Password Guessing (Credential Access). Repeated failed authentications for a single account from a single source are consistent with systematically guessing that account's password. (A spray against many accounts would be T1110.003 and is not what was observed.) (confidence 0.90)
Evidence: 0cb61159ea3d69dcc87a, d92873fb243f9f0bcb0d, 3bdd60cc3a5a97b84519, a068ff51cd2cb23d2f8d, 2108af7a380995a548b5, 6e10a5cc29314bc6a964, +7 more
Assessed: Behaviour cited by ATH-007 is consistent with T1569.002 System Services: Service Execution (Execution). A command interpreter was started by the Service Control Manager, which is the defining behaviour of executing a payload as a Windows service. (confidence 0.90)
Evidence: c1aa4d45ddf2102946f7
Assessed: Behaviour cited by ATH-005 is consistent with T1078 Valid Accounts (Persistence). A successful authentication followed the failure burst, which is consistent with the account credential now being under adversary control. (confidence 0.60)
Evidence: 0cb61159ea3d69dcc87a, d92873fb243f9f0bcb0d, 3bdd60cc3a5a97b84519, a068ff51cd2cb23d2f8d, 2108af7a380995a548b5, 6e10a5cc29314bc6a964, +7 more
Assessed: Behaviour cited by ATH-007 is consistent with T1021.002 Remote Services: SMB/Windows Admin Shares (Lateral Movement). Command output was redirected to an administrative share, indicating the service was driven over an authenticated SMB session from another host. (confidence 0.60)
Evidence: c1aa4d45ddf2102946f7
Assessed: The case spans 4 ATT&CK tactics (Execution -> Persistence -> Credential Access -> Lateral Movement). Progression across multiple tactics is harder to explain as coincidental than activity confined to one. (confidence 0.80)
Evidence: 0adbb9ef85b9188c8683, 0cb61159ea3d69dcc87a, 0cc680d6694f1f8615a1, 2108af7a380995a548b5, 3bdd60cc3a5a97b84519, 67a9f5bfab28871757dd, +8 more

Unconfirmed Hypotheses (0)

None.

Recommended Next Steps

Investigative recommendations for a human analyst. No response action has been taken or is authorised by this report.

Retrieve email gateway or web-proxy logs to establish the initial access vector.
Rationale: No detection in this case targets initial access, so the delivery mechanism (e.g. a phishing attachment) is inferred from process lineage rather than confirmed from delivery telemetry.
Based on: MITRE ATT&CK tactic coverage gap: Initial Access
Independently verify account activity on all hosts in scope (WS-2138, WS-9673) rather than relying solely on the correlated case, in case related activity exists that current detections did not flag.
Rationale: This case spans multiple hosts, which increases the possible blast radius.
Based on: case.is_multi_host
Escalate to a human analyst for validation before any remediation action is taken.
Rationale: This system performs read-only investigation only. It has no capability to disable accounts, isolate hosts, or otherwise remediate, and this report is not authorisation to do so.
Based on: system design constraint

Limitations & Scope

Telemetry underlying this report came from: generated_auth_execution. Field coverage depends entirely on what the originating export or sensor captured; this project's canonical schema does not model every field a real EDR product exposes (e.g. file hashes, signer information, session identifiers), and any of those were dropped during normalization.
ATT&CK mappings are interpretations of observed behaviour against a public taxonomy. They indicate that behaviour is consistent with a technique, not that an adversary performed it.
Grouping confidence describes how strongly correlated findings are linked to each other, not whether an intrusion occurred.
No evidence was found for the following ATT&CK tactics: Initial Access, Discovery, Collection, Exfiltration. Their absence may reflect that the activity did not occur, or that available telemetry cannot observe it.
Typed predicates are checked against recorded telemetry; free-text interpretations are not semantically verified. Missing identity is not a confirmed process link, and recorded event order does not establish causation.
No evidence was found for the following tactics: Collection. Their absence may reflect either that the activity did not occur or that we lack the telemetry to see it.

Investigation Trace

Agents run: endpoint, identity, attack; tool calls made: 8

step 1: endpoint -- deterministic priority order; case evidence rests on process_command_line, process_execution, process_lineage telemetry (from ATH-007)
step 2: identity -- deterministic priority order; case evidence rests on auth_source_attribution, authentication telemetry (from ATH-005)
step 3: attack -- only eligible specialist; case has ATT&CK mappings and domain evidence has been gathered
step 4: stop -- no specialist has further useful work on the available evidence
evidence verification: 30 checked observations; 5 summaries reclassified

Evidence Appendix

All 28 telemetry events underlying this report, chronologically.

Event ID	Time	Device	User	Summary
`0cb61159ea3d69dcc87a`	08:00:00	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`98c80712635dec2f3738`	08:00:00	WS-9673	acct-2520	wininit.exe -> services.exe \| services.exe
`0ce208dd57c057228f55`	08:00:00	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`d92873fb243f9f0bcb0d`	08:00:20	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`8144033a5e9cd2c19c38`	08:00:29	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`3bdd60cc3a5a97b84519`	08:00:40	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`78274bf69ec1ff508093`	08:00:58	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`a068ff51cd2cb23d2f8d`	08:01:00	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`2108af7a380995a548b5`	08:01:20	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`c532eb018e1154acca2e`	08:01:27	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`6e10a5cc29314bc6a964`	08:01:40	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`7c156d83425329cf030a`	08:01:56	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`a3bf61cc981c8d0cdd5d`	08:02:00	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`f6497a719ee487d49e5a`	08:02:20	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`0d4ac76c0560bdbb704b`	08:02:25	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`0cc680d6694f1f8615a1`	08:02:40	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`dfd20d6fe31907ff2b86`	08:02:54	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`8407329aafd15d9c0a9e`	08:03:00	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`0adbb9ef85b9188c8683`	08:03:20	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`fbe91286e9d9acc93b9e`	08:03:23	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`bc5bc87bcd4bf9827807`	08:03:40	WS-9673	acct-2520	failure logon [Network (SMB / share access)] from 10.10.2.8 reason=bad_password
`e5a3cce5c1c4a821f59d`	08:03:52	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`9ad22469dab49a3df6fc`	08:04:21	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`5c0abbbce84e1b2a43fa`	08:04:50	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`67a9f5bfab28871757dd`	08:05:00	WS-9673	acct-2520	success logon [Network (SMB / share access)] from 10.10.2.8
`9b73d640145c27f1eddb`	08:05:19	OFFICE-01	acct-2520	success logon [Interactive (console)] from 10.10.1.5
`c1aa4d45ddf2102946f7`	08:06:00	WS-9673	acct-2520	services.exe -> cmd.exe \| cmd.exe /Q /c job.cmd 1> \\127.0.0.1\ADMIN$\job.log 2>&1
`0b092d00f3798939dd00`	08:06:05	WS-9673	acct-2520	cmd.exe -> dism.exe \| dism.exe /Online /Cleanup-Image /ScanHealth