Cisco Umbrella Alert Details
Alert ID: UMBRELLA-DYNAMIC-RES-1568-7842 Alert Time: 2024-03-01 16:30:45 EST Severity: HIGH (88/100) Source: Cisco Umbrella Investigate Rule: “Fast-Flux DNS – Malware C2 Detection” MITRE ATT&CK: T1568.001 – Dynamic Resolution: Fast Flux DNS
Alert Details:
Detection: Domain using fast-flux DNS (multiple IPs) with malicious reputation
Domain: cdn-update-service[.]com First Seen: 2024-03-01 10:00 EST Query Source: Multiple internal hosts (12 hosts)
DNS Resolution History:
10:00:15 – 185.143.221.89 (Bulgaria)
10:05:22 – 194.165.16.78 (Romania)
10:10:18 – 203.0.113.45 (Netherlands)
10:15:33 – 45.134.225.12 (Russia)
10:20:47 – 89.248.165.67 (Ukraine)
(changing every 5-10 minutes)
Internal Hosts Querying:
ENG-WS-045 (engineering) – 12 queries
FIN-WS-078 (finance) – 8 queries
HR-WS-023 (hr) – 5 queries
MKT-WS-112 (marketing) – 4 queries
(12 total hosts, 47 queries)
Detection Logic:
Domain resolves to multiple IPs (fast-flux)
IPs across multiple countries (unusual)
Domain age: 2 days (newly registered)
Multiple internal hosts querying (potential widespread compromise)
Pattern matches malware C2 using fast-flux
Threat Intelligence:
Domain associated with “QakBot” malware family
Fast-flux used to evade IP blocking
47 queries from internal network
SOC Investigation Process
Step
Action
Tools Used
Findings
1. Alert Validation
Verify Umbrella alert
Cisco Umbrella Dashboard
Confirmed fast-flux domain with multiple internal queries
2. Host Investigation
Identify hosts querying domain
CrowdStrike Falcon
12 hosts with Cobalt Strike beacons
3. Malware Analysis
Extract beacon samples
CrowdStrike Sandbox
QakBot malware using fast-flux C2
4. Immediate Action
Isolate all affected hosts
CrowdStrike
12 hosts quarantined
5. C2 Blocking
Block domain and IPs
Umbrella, Palo Alto
Domain and all associated IPs blocked
6. Malware Removal
Clean all affected hosts
CrowdStrike Live Response
Beacons removed; hosts reimaged
Jira Incident Report
Ticket: SOC-2024-154 Summary: T1568 – Fast-Flux C2 Domain Affecting 12 Hosts Status: RESOLVED Resolution: MALICIOUS – C2 Disrupted, Hosts Cleaned Priority: P1 – CRITICAL Labels: T1568, dynamic-resolution, fast-flux, qakbot, cisco-umbrella, widespread Components: Network-Security, Endpoint-Security
INCIDENT ANALYSIS REPORT
1. Initial Context:
Detection Source: Cisco Umbrella Investigate.
Alert: “Fast-Flux DNS – Malware C2 Detection”.
Domain: cdn-update-service[.]com.
Queries: 47 queries from 12 internal hosts.
Time: 2024-03-01 16:30 EST.
Technique: MITRE ATT&CK T1568.001 – Dynamic Resolution: Fast Flux DNS.
2. Technical Analysis:
Fast-Flux Details:
Domain: cdn-update-service[.]com (registered 2024-02-28)
IPs: 6 different IPs across 5 countries
TTL: 300 seconds (5 minutes)
Flux Rate: IP changes every 5-10 minutes
Affected Hosts (12):
Engineering: 3 hosts (ENG-WS-045, 046, 047)
Finance: 2 hosts (FIN-WS-078, 079)
HR: 2 hosts (HR-WS-023, 024)
Marketing: 2 hosts (MKT-WS-112, 113)
Sales: 3 hosts (SALES-WS-023, 024, 025)
Malware Analysis:
Type: QakBot banking trojan
C2: cdn-update-service[.]com
Beacon Interval: 5 minutes
Capabilities: Credential theft, keylogging, remote access
Common Infection Vector:
All 12 users clicked phishing email with same attachment
Email subject: “Invoice Overdue”
Attachment: invoice_7842.docm (macro-enabled)
3. Investigation Findings:
Timeline:
09:00 – Phishing emails sent
09:15-10:00 – Users clicked attachments
10:00-16:00 – Beacons active, fast-flux DNS
16:30 – Umbrella alert
16:32 – SOC investigates
16:35 – All 12 hosts identified
16:40 – Hosts isolated
16:45 – Domain blocked
Indicators of Compromise (IoCs):
Domain:
– cdn-update-service[.]com (blocked)
IPs:
– 185.143.221.89, 194.165.16.78, 203.0.113.45, 45.134.225.12, 89.248.165.67
File:
– invoice_7842.docm (SHA256: a1b2c3d4…)
Hosts:
– 12 compromised workstations (list attached)
4. Containment Actions:
Immediate Actions:
Isolated all 12 affected hosts via CrowdStrike.
Blocked domain and all associated IPs at firewall and Umbrella.
Terminated beacon processes on all hosts.
Host Remediation:
All 12 hosts reimaged.
User passwords reset.
MFA enforced for all.
Email Remediation:
Quarantined phishing email from all mailboxes.
Blocked sender domain.
5. Root Cause Analysis:
Primary Cause: Widespread phishing campaign with macro-enabled documents.
Contributing Factors:
Macros enabled in Office.
No ASR rule blocking Office child processes.
Users lacked recent training.
6. Business Impact:
Operational Impact: 12 workstations offline for 4 hours.
Data Exposure: Potential credential theft; investigation ongoing.
Productivity Impact: Significant across multiple departments.
7. Remediation & Prevention:
Completed Actions:
C2 disrupted.
12 hosts cleaned.
Passwords reset.
MFA enforced.
Technical Controls Enhanced:
Enabled ASR rule “Block Office applications from creating child processes”.
Blocked macros from internet via GPO.
Enhanced email filtering for invoice-themed emails.
Deployed additional security awareness training.
8. Conclusion:
A widespread phishing campaign infected 12 hosts with QakBot malware using fast-flux DNS to evade IP blocking. Cisco Umbrella detected the fast-flux pattern and enabled rapid identification and isolation of all affected hosts before significant data loss.
Closure Rationale: C2 disrupted; all hosts cleaned; passwords reset.
Analyst: [Your Name], SOC Analyst Date: 2024-03-01 17:30 EST