Author: CyberDudeBivash
Powered by: CyberDudeBivash Brand | cyberdudebivash.com
Related:cyberbivash.blogspot.com

 Daily Threat Intel by CyberDudeBivash
Zero-days, exploit breakdowns, IOCs, detection rules & mitigation playbooks.

Follow on LinkedInApps & Security ToolsAuthor: CyberDudeBivash
Powered by: CyberDudeBivash Brand | cyberdudebivash.com
Related:cyberbivash.blogspot.com

CISO Briefing: Is Your PC Secretly Stealing Your Passwords? 15+ “Trusted” App Installers Were Found with Malware. (A CISO’s Hunt Guide) — by CyberDudeBivash

By CyberDudeBivash · 01 Nov 2025 · cyberdudebivash.com · Intel on cyberbivash.blogspot.com

LinkedIn: ThreatWirecryptobivash.code.blog

FILELESS MALWARE • LNK/JS EXPLOIT • EDR BYPASS • THREAT HUNTING

Situation: This is a CISO-level “Shadow IT” warning. Attackers are using SEO Poisoning and Malvertising to push “Trojan Horse” versions of 15+ “trusted” enterprise apps (like PuTTY, WinSCP, Slack, and Teams). This TTP is *designed* to bypass your EDR (Endpoint Detection and Response).

This is a decision-grade CISO brief. This is a “Living off the Land” (LotL) attack. The TTP is a malicious `.JS` (JavaScript) or `.LNK` (Shortcut) file inside a “setup.zip”. This attack *bypasses* your EDR because it runs a fileless PowerShell script *inside a “trusted” Windows process* (`wscript.exe`). This is the new kill chain for infostealers, MFA-bypassing session hijacking, and ransomware.

TL;DR — Attackers are pushing fake “PuTTY” installers via Google Ads to bypass EDR.

• The TTP: SEO Poisoning / Malvertising → User Googles “Download PuTTY” → Clicks top (malicious) ad → Downloads `putty.zip`.
• The “EDR Bypass”:** The ZIP contains a fileless loader (`.JS` or `.LNK`) that runs *inside* a trusted Windows process (`wscript.exe` / `powershell.exe`).
• The Impact: Infostealer (Redline/Vidar) → Steals *all* passwords, credit cards, and *session cookies* (MFA Bypass).
• THE ACTION (CISO): 1) HARDEN: *De-weaponize `.JS` files*. Change the default handler from `wscript.exe` to `notepad.exe` via GPO. 2) HUNT: This is the mandate. Hunt for anomalous `wscript.exe` child processes *now*.

TTP Factbox: “Trusted Installer” (Gootloader) Attack

TTP	Component	Severity	Exploitability	Mitigation
Malvertising (T1566.002)	Google Ads / SEO Poisoning	Critical	Bypasses SEG	User Training / MDR
Fileless Malware (T1059.007)	`.JS` File -> `wscript.exe`	Critical	EDR Bypass (LotL)	GPO Hardening / MDR

Fileless BackdoorEDR Bypass TTPLiving off the Land (LotL)Contents

1. Phase 1: The “Trusted” Trojan (Why Your EDR is Blind)
2. Phase 2: The Kill Chain (From “Google” to “Session Hijack”)
3. Exploit Chain (Engineering)
4. Reproduction & Lab Setup (Safe)
5. Detection & Hunting Playbook (The *New* SOC Mandate)
6. Mitigation: The 5-Step CISO/Consumer Checklist
7. Audit Validation (Blue-Team)
8. Tools We Recommend (Partner Links)
9. CyberDudeBivash Services & Apps
10. FAQ
11. Timeline & Credits
12. References

Phase 1: The “Trusted” Trojan (Why Your EDR is Blind)

As a CISO, you’ve spent millions on a “Next-Gen” EDR (Endpoint Detection and Response) stack. Your vendor promised “AI-powered protection.” Yet, this attack bypasses it completely. Why?

It’s because this attack *never uses a “virus”*. It’s a “Living off the Land” (LotL) attack that exploits your EDR’s *trust*.

1. The SEO Poisoning (The “Bait”)

Your Secure Email Gateway (SEG) is useless. The attack doesn’t *start* with an email. It starts with your *sysadmin* Googling a “benign” term:

• “download putty”
• “download winscp”
• “slack for windows download”

The Gootloader gang *poisons* Google’s search results (or uses Malvertising) to make their *malicious website* (a fake “Download Now” page) rank #1.

2. The “ZIP Trick” (The “Wrapper”)

The user, *trusting Google*, clicks the link. The fake forum says “Click here to download.” It delivers a `.ZIP` file. This is the “wrapper” to get the payload past any *network-level* scanners.

3. The “Trusted Process” (The “Bypass”)

The user opens the ZIP. Inside is a file: `putty_installer.pdf.js`.
Your employee, *not seeing the `.js` extension* (because Windows hides it by default), double-clicks.

This does *not* open an installer. It launches `wscript.exe` (Windows Script Host), a *legitimate, signed Microsoft tool*.

Your EDR *sees* `wscript.exe` running. It is *whitelisted* to trust this process. It *allows* it.
This is a *fileless attack*. The `.JS` script *never* drops a “malware.exe”. It runs *entirely in memory* inside the “trusted” `wscript.exe` process.

Phase 2: The Kill Chain (From “Google” to “Session Hijack”)

This is the full ransomware and espionage kill chain that our Incident Response (IR) teams are seeing in the wild.

Stage 1: Initial Access (The Google Search)

Your sysadmin, `admin@yourcompany.com`, clicks a poisoned Google search result for “PuTTY”.

Stage 2: Execution (The `.JS` Click)

The user opens `putty.zip` and double-clicks `putty.exe.js`. The `wscript.exe` process executes the in-memory script.

Stage 3: C2 & Persistence (The “EndClient” Backdoor)

The fileless `.JS` script (the “Gootloader” payload) does two things:

1. C2 Beacon: It spawns *another* trusted process, `powershell.exe -e …`, to make an *outbound HTTPS connection* to an attacker’s C2 server (a “C2 beacon”).
2. Persistence: It creates a new `Scheduled Task` or `Registry Run Key` to *re-launch* this same fileless script every time the user logs in.

The attacker now has a *persistent backdoor* on your sysadmin’s machine. The breach is complete.

Stage 4: Post-Exploitation (The “Hostage”)

The attacker is now on your *sysadmin’s* PC. They have “God Mode” on that box.

• They run Mimikatz *in-memory* to steal the admin’s `Domain Admin` credentials.
• They steal *all* browser session cookies (Session Hijacking) to bypass MFA on AWS, M365, and your VPN.
• They pivot to your Domain Controller.
• They exfiltrate your “4TB” of CUI, PII, and IP.
• They deploy Ransomware.

Exploit Chain (Engineering)

This is a “Trusted Process” Hijack (T1219/T1059). The “exploit” is a *logic* flaw in your EDR Whitelisting policy.

• Trigger: User double-clicks `.js` file.
• Precondition: EDR/AV is configured to *automatically trust* all `wscript.exe` / `cscript.exe` processes. Windows “Hides known file extensions” is ON.
• Sink (The RCE): `explorer.exe` → `wscript.exe file.js` → `powershell.exe -e …` (Fileless C2)
• Module/Build: `wscript.exe` (Trusted), `powershell.exe` (Trusted).
• Patch Delta: There is no “patch.” The “fix” is GPO Hardening (changing the default `.js` handler) and MDR (Threat Hunting).

Reproduction & Lab Setup (Safe)

You *must* test your EDR’s visibility for this TTP.

• Harness/Target: A sandboxed Windows 11 VM with your standard EDR agent installed.
• Test: 1) Create a file named `test.js`. 2) Put this *one line* of code in it: `WScript.CreateObject(“WScript.Shell”).Run(“calc.exe”);`
• Execution: Double-click the `test.js` file.
• Result: Did `calc.exe` launch? Did your EDR fire a P1 (Critical) alert for `wscript.exe -> calc.exe`? If it was *silent*, your EDR is *blind* to this TTP.
• Safety Note: If `calc.exe` can run, so can the “EndClient” RAT.

Detection & Hunting Playbook (The *New* SOC Mandate)

Your SOC *must* hunt for this. Your SIEM/EDR is blind to the exploit itself; it can *only* see the *result*. This is your playbook.

• Hunt TTP 1 (The #1 IOC): “Anomalous Child Process.” This is your P1 alert. Your `wscript.exe` process should *NEVER* spawn a shell (`powershell.exe`, `cmd.exe`, `/bin/bash`).# EDR / SIEM Hunt Query (Pseudocode) SELECT * FROM process_events WHERE (parent_process_name = ‘wscript.exe’ OR parent_process_name = ‘cscript.exe’) AND (process_name = ‘powershell.exe’ OR process_name = ‘cmd.exe’)
• Hunt TTP 2 (The C2): “Show me all *network connections* from `wscript.exe` or `cscript.exe` to a *newly-registered domain* or *anomalous IP*.”
• Hunt TTP 3 (The Persistence): “Show me *all new* Scheduled Tasks or Registry Run Keys that contain `wscript.exe` or `cscript.exe`.”

Mitigation: The 5-Step CISO/Consumer Checklist

This is a *hybrid* threat. It requires a *hybrid* defense. This is the CyberDudeBivash 5-Step Checklist.

1. (CISO) HARDEN YOUR ENDPOINTS (The #1 Fix)

This is your CISO mandate. De-weaponize JavaScript files.
You must *change the default file handler* for `.JS` files. An employee should *never* “execute” a `.JS` file. It should *open* in Notepad.
The Fix: Use GPO to change the default handler for `.js` files from `wscript.exe` (Execute) to `notepad.exe` (View). This *kills* the TTP.

2. (CISO) Deploy 24/7 Human-Led MDR

Your EDR is *blind* without a *human hunter*. You *must* have a 24/7 Managed Detection and Response (MDR) team (like ours) to hunt for the `wscript -> powershell` TTPs that your automated tools *will* miss.

3. (CISO) Deploy Session Monitoring (The “Alarm”)

The user *will* be breached. You *must* detect the *session hijack*.
SessionShield is the *only* tool that “fingerprints” your employee’s *real* session. The *instant* an attacker “hijacks” that M365 session from a new IP, SessionShield *kills the session*.

4. (Consumer/CISO) TRAIN Your People on “LotL”

Your *new* training (like from Edureka) must be: “Do not trust Google. Do not download `.ZIP` files. Do not trust *any* file ending in `.js`, `.lnk`, or `.vbs`.”

5. (Consumer/CISO) Deploy Endpoint Security (EDR)

This *entire* attack *starts* with an Infostealer. You *must* have a *behavioral* antivirus/EDR that can *block* this fileless TTP.

Recommended Tool: Kaspersky EDR is built to *block* infostealers (like Redline) and *detect* the fileless “PowerShell” TTP *before* your data is stolen.
Get Kaspersky EDR (Partner Link) →

Audit Validation (Blue-Team)

Run this *today*. This is not a “patch”; it’s an *audit*.

# 1. Audit your EDR (The "Lab" Test)
# Run the "Lab Setup" test (`test.js -> calc.exe`). 
# Did your EDR *see* it? If not, it is BLIND.

# 2. Audit your File Handlers
# (Run `ftype JScript.file`)
# Does it say "wscript.exe"? If yes, you are VULNERABLE.
# Run the GPO to change it to "notepad.exe".

# 3. Run the "Lab Test" again
# Did `calc.exe` launch? Or did `notepad.exe` open?
# If Notepad opened, you have *successfully* hardened your fleet.
  

Is Your EDR Blind to “Fileless” Attacks?
Your SOC is slow. Your EDR is whitelisted. CyberDudeBivash is the leader in Ransomware Defense. We are offering a Free 30-Minute Ransomware Readiness Assessment to show you the *exact* gaps in your “LotL” and “Fileless” defenses.

Book Your FREE 30-Min Assessment Now →

Recommended by CyberDudeBivash (Partner Links)

You need a layered defense. Here’s our vetted stack for this specific threat.

Kaspersky EDR
This is your *sensor*. It’s the #1 tool for providing the behavioral telemetry (process chains, network data) that your *human* MDR team needs to hunt.Edureka — Threat Hunting Training
Your SOC team can’t find what they don’t know. Train them *now* on PowerShell Threat Hunting and LotL TTPs.TurboVPN
The phish often lands on a *remote* device on *public Wi-Fi*. A VPN encrypts this initial access channel.

Alibaba Cloud (VDI)
A key mitigation. Use Virtual Desktop Infrastructure (VDI). If the VDI is popped, you *burn it* and re-image in seconds. The host is safe.AliExpress (Hardware Keys)
*Mandate* this for all Domain Admins. Get FIDO2/YubiKey-compatible keys. They stop the *initial phish* from succeeding.Rewardful
Run a bug bounty program. Pay white-hats to find flaws *before* APTs do.

CyberDudeBivash Services & Apps

We don’t just report on these threats. We hunt them. We are the “human-in-the-loop” that your automated EDR is missing.

• Managed Detection & Response (MDR): This is the *solution*. Our 24/7 SOC team becomes your Threat Hunters, watching your EDR logs for these *exact* “wscript -> powershell” TTPs.
• Adversary Simulation (Red Team): This is the *proof*. We will *simulate* this exact “Fileless” Gootloader kill chain to show you where you are blind.
• Emergency Incident Response (IR): You found this TTP? Call us. Our 24/7 team will hunt the attacker and eradicate them.
• PhishRadar AI — Stops the phishing attacks that *initiate* the breach.
• SessionShield — Protects your *admin sessions* from the *credential theft* that happens after this breach.

Book Your FREE 30-Min AssessmentExplore 24/7 MDR ServicesSubscribe to ThreatWire

FAQ

Q: What is Gootloader?
A: Gootloader is a malware loader (a “dropper”). It’s the “first stage” of a breach. It uses SEO Poisoning to get onto a PC and then runs a fileless `.JS` or `.LNK` script to install a *real* backdoor (like a C2 beacon or ransomware).

Q: What is a LNK/JS exploit?
A: It’s not a “vulnerability” in LNK/JS files themselves, but a *technique*. It leverages a legitimate Windows function (shortcuts/scripts) to execute malicious code (like PowerShell) in a “fileless” way that evades simple antivirus.

Q: Why does my EDR/Antivirus miss this attack?
A: Because your EDR is *configured to trust* `wscript.exe` and `powershell.exe`. This is a “Trusted Process” bypass. The EDR sees a ‘trusted’ Microsoft process running and *ignores* it. You *must* have a *human* MDR team hunting for the *behavioral* anomalies.

Q: What is the #1 action to take *today*?
A: HARDEN. Go to your Group Policy (GPO) and *change the default file handler* for `.JS` and `.VBS` files from `wscript.exe` (Execute) to `notepad.exe` (View). This *de-weaponizes* the TTP instantly. Your *second* action is to call our team to run an emergency Threat Hunt for this TTP.

Timeline & Credits

This “Gootloader” TTP (T1566.001 / T1059) is an active, ongoing campaign by multiple APTs and RaaS groups.
Credit: This analysis is based on active Incident Response engagements by the CyberDudeBivash threat hunting team.

References

• MITRE ATT&CK: T1059.007 (JavaScript)
• MITRE ATT&CK: T1059.001 (PowerShell)
• CyberDudeBivash MDR Service

Affiliate Disclosure: We may earn commissions from partner links at no extra cost to you. These are tools we use and trust. Opinions are independent.

CyberDudeBivash — Global Cybersecurity Apps, Services & Threat Intelligence.

cyberdudebivash.com · cyberbivash.blogspot.com · cryptobivash.code.blog

#Gootloader #LNKexploit #ZIP #FilelessMalware #PowerShell #EDRBypass #Ransomware #CyberDudeBivash #IncidentResponse #MDR #ThreatHunting #LotL #C2