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Cybercriminals are increasingly exploiting software downloads to distribute malware, often disguising malicious payloads as legitimate applications. A recent example involves fake Google ads promoting a compromised version of RVTools, a VMware utility, which delivered ThunderShell (SMOKEDHAM), a PowerShell-based Remote Access Tool (RAT). This highlights the growing sophistication of malvertising—a threat that persists despite increased awareness.
Read the full report on The Hacker News: https://lnkd.in/dVvD3b5w
You Should Know: How to Mitigate Malware from Unauthorized Downloads
1. Restrict Software Installations via Group Policy (Windows)
Prevent non-admin users from installing software:
Enable Software Restriction Policy via GPO gpedit.msc → Computer Configuration → Windows Settings → Security Settings → Software Restriction Policies
– Set “Disallowed” as the default security level.
– Whitelist trusted paths (e.g., C:\Program Files\).
2. Use AppLocker to Block Untrusted Executables
Configure AppLocker rules Get-AppLockerPolicy -Effective | Export-AppLockerPolicy -Xml -File "C:\rules.xml"
– Block .exe, .ps1, and `.msi` files from %USERPROFILE%\Downloads.
3. Deploy PowerShell Execution Policies
Restrict malicious PowerShell scripts:
Set-ExecutionPolicy -ExecutionPolicy Restricted -Scope CurrentUser
4. Monitor Network Traffic for RATs
Detect ThunderShell/SMOKEDHAM connections:
Linux (iptables rule to block suspicious outbound traffic) iptables -A OUTPUT -p tcp --dport 443 -m string --string "thundershell" --algo bm -j DROP
5. Implement Browser-Level Protections
- Disable automatic downloads in Chrome:
bash://settings/content/downloads→ Toggle “Ask where to save each file before downloading” - Use uBlock Origin to block malvertising domains.
6. Educate Users on Red Flags
- Avoid “cracked” software (e.g., pirated MS Office).
- Verify checksums of legitimate downloads (e.g., VMware tools):
sha256sum RVTools.exe
What Undercode Say
The shift toward zero-trust user policies is critical. Attackers exploit human behavior—whether through fake ads, trojanized installers, or “productivity” scripts. Technical controls like AppLocker, network segmentation, and execution restrictions must complement user training.
Linux Admins: Use `chmod` to restrict execution:
chmod -R 750 /opt/trusted_software
Windows Admins: Audit installed software weekly:
Get-WmiObject -Class Win32_Product | Select Name, Version
Malvertising won’t disappear, but proactive hardening will.
Expected Output:
A locked-down environment where:
- Users cannot install unauthorized software.
- PowerShell scripts require admin approval.
- Network egress filters block RAT callbacks.
- Downloads are scanned and validated.
Stay paranoid.
References:
Reported By: Charlescrampton Stop – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
