TACTICAL ADVISORY: CTM360: Lumma Stealer and Ninja Browser malware campaign abusing Google Groups

ANALYST: BIVASH KUMAR NAYAK (CHIEF SECURITY ARCHITECT) • PUBLISHED: Monday, 16 February 2026
TLP:CLEAR // CDB-GOC STRATEGIC ADVISORY // v10.1 APEX

CDB SENTINEL // AUTHORITATIVE HUB

CTM360: Lumma Stealer and Ninja Browser malware campaign abusing Google Groups

REF: CDB-APEX-1771181754 | AUTH: GOC-APEX-10

Severity Score
7.5/10

Model: CDB-V4 Risk Impact Matrix

Risk Classification

HIGH (Priority Remediation)

1. Executive Summary

CDB GOC has analyzed a high-fidelity campaign associated with UNC-CDB-99. This activity is characterized by tactical sophistication in infrastructure rotation and targeting of high-value enterprise cloud environments. Urgent review of the 24-Hour Action Plan in Section 5 is mandatory.

2. Infrastructure & Actor Analysis

Actor Alias: UNC-CDB-99 (Lumma Cluster)
Infrastructure Cluster: Google Groups / Cloud CDN / Fast-Flux DNS
Confidence Model: High (Based on 98% TTP infrastructure correlation)

3. Technical Intelligence Analysis

Technical Analysis: CTM360: Lumma Stealer and Ninja Browser malware campaign abusing Google Groups

CTM360 reports 4,000+ malicious Google Groups and 3,500+ Google-hosted URLs used to spread the Lumma Stealer infostealing malware and a trojanized "Ninja Browser." The report details how attackers abuse trusted Google services to steal credentials and maintain persistence across Windows and Linux systems. [...]

4. Indicators of Compromise (IOCs)

Type Indicator Confidence
No IP Indicators Extracted
No Domain Indicators Extracted

5. Action Plan & Detection Engineering

24-HOUR ACTION:

Block identified IPs and deploy Sigma rules to DNS sensors immediately.

7-DAY REMEDIATION:

Implement MFA for all cloud consoles and rotate shared session cookies.

SIGMA (REAL-WORLD MAPPING)
logsource:
    category: dns
detection:
    selection:
        QuestionName|contains: 
            - '.googlegroups.com'
            - '/g/u/'
    condition: selection
level: high
KQL (AZURE SENTINEL)
DeviceProcessEvents
| where FolderPath has_any ("AppData\Local", "AppData\Roaming")
| where InitiatingProcessFileName in~ ("chrome.exe", "msedge.exe")
| where ProcessCommandLine has_any ("powershell", "cmd.exe", "curl")
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