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CISO Briefing: Your Hiring Process Is an EDR-Bypassing Backdoor. How to Hunt the “Job Seeker” Attack. (A PostMortem) — by CyberDudeBivash

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

LinkedIn: ThreatWire cryptobivash.code.blog

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

Situation: Your *hiring process* is now a critical attack vector. APTs (Advanced Persistent Threats) and ransomware gangs (like Gootloader) are targeting your *HR department* because it’s the *one* department *required* to open untrusted attachments (resumes) from strangers.

This is a decision-grade CISO brief. This is a “Living off the Land” (LotL) attack. The TTP is a malicious `.JS` or `.LNK` file inside a “resume.zip”. This attack *bypasses* your EDR (Endpoint Detection and Response) because it runs a fileless PowerShell script *inside a “trusted” Windows process* (`wscript.exe`). This is the new kill chain for data exfiltration, and your SOC is blind.

TL;DR — Attackers are sending malicious `.JS` “resumes” in `.ZIP` files to HR to bypass EDR.

The TTP: Phishing Email (`careers@…`) → `resume.zip` → User clicks `resume.pdf.js` → `wscript.exe` (Trusted) → `powershell.exe -e …` (Fileless C2 Beacon).
The “EDR Bypass”: Your EDR is *whitelisted* to *trust* `wscript.exe` (Windows Script Host). It sees a “trusted” Microsoft process running and *ignores* it.
The Risk: This “backdoor” is the foothold for ransomware, corporate espionage, and PII data exfiltration (like stealing all your *other* employee SSNs).
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. You *must* hunt for anomalous `wscript.exe` child processes and network traffic *now*.

TTP Factbox: “Job Seeker” (Gootloader) Attack

TTP	Component	Severity	Exploitability	Mitigation
Phishing (T1566.001)	`.JS` in `.ZIP` Attachment	Critical	SEG Bypass	PhishRadar AI / Filter Rules
Fileless Malware (T1059.007)	`.JS` File -> `wscript.exe`	Critical	EDR Bypass (LotL)	MDR (Threat Hunting)

Fileless BackdoorEDR Bypass TTPLiving off the Land (LotL)Contents

Phase 1: The “HR Vector” (Why Your Training & EDR Fail)

As a CISO, you’ve spent millions on a “Next-Gen” EDR (Endpoint Detection and Response) stack and *hours* on “Security Awareness Training.” This one TTP bypasses *both*.

1. The “Training” Bypass (The Lure)

Your training says, “Don’t open attachments from strangers.” But what is your *HR department’s* job? It is *explicitly* to open attachments (resumes) from strangers. Attackers (like the Gootloader gang) *know* this.
They don’t email your C-suite. They email `careers@yourcompany.com` with a “benign” message: “To the Hiring Manager: Please find my resume attached for the ‘Open Role’. [resume.zip].”

2. The “SEG” Bypass (The “ZIP Trick”)

Your Secure Email Gateway (SEG) is configured to block `.exe` and `.ps1` files. It is *not* configured to block `.ZIP` files, because your business *needs* them. The attacker’s malicious `.JS` (JavaScript) or `.LNK` file is hidden inside this “allowed” ZIP.

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

The HR user opens `resume.pdf.js`. By default, Windows *hides* the `.js` extension, so the user *only sees* `resume.pdf`.
This file is *not* a PDF. It’s a script. It *executes* using `wscript.exe` (Windows Script Host).
Your EDR sees `wscript.exe` (a *trusted, signed Microsoft tool*) running. It *allows* this.
This is a *fileless attack*. No “malware.exe” is *ever* written to disk. Your EDR, configured to “trust” `wscript.exe`, is now 100% blind to the malicious code running inside it.

Phase 2: The “Fileless” Kill Chain (From Click to C2 Beacon)

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 HR Inbox)

The attacker sends their “resume.zip” to `careers@yourcompany.com`.

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

The HR user, doing their job, opens `resume.pdf.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:

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”).
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 HR department’s machine. The breach is complete.

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

The attacker is now *inside* your network on an HR computer. They have access to *all your PII*:

They steal all *other* employee SSNs, bank info, and salaries. (GDPR/DPDP nightmare).
They use this “trusted” PC to 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 & Hardening (The CISO Mandate)

This is a Windows Configuration failure. This is the fix.

1. HARDEN (The *Real* 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. HUNT (The “MDR” Fix): You *cannot* run a 9-to-5 SOC. You *must* have a 24/7 human-led MDR team (like ours) to hunt for the *behavioral* TTPs (like Hunt TTP 1) that your EDR will log but *not* alert on.
3. VERIFY (The “Red Team” Fix): You *must* run an Adversary Simulation (Red Team) to *prove* your EDR and your SOC team *can* detect this TTP.

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?
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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.

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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

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

Cyberdudebivash

Your Hiring Process Is Now a Major Attack Vector. A CISO’s Guide to the “Job Seeker” Attack Bypassing Your EDR.

CISO Briefing: Your Hiring Process Is an EDR-Bypassing Backdoor. How to Hunt the “Job Seeker” Attack. (A PostMortem) — by CyberDudeBivash

Phase 1: The “HR Vector” (Why Your Training & EDR Fail)

1. The “Training” Bypass (The Lure)

2. The “SEG” Bypass (The “ZIP Trick”)

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

Phase 2: The “Fileless” Kill Chain (From Click to C2 Beacon)

Stage 1: Initial Access (The HR Inbox)

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

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

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

Exploit Chain (Engineering)

Reproduction & Lab Setup (Safe)

Detection & Hunting Playbook (The New SOC Mandate)

Mitigation & Hardening (The CISO Mandate)

Audit Validation (Blue-Team)

Recommended by CyberDudeBivash (Partner Links)

CyberDudeBivash Services & Apps

FAQ

Timeline & Credits

References

Leave a comment Cancel reply

Your Hiring Process Is Now a Major Attack Vector. A CISO’s Guide to the “Job Seeker” Attack Bypassing Your EDR.

CISO Briefing: Your Hiring Process Is an EDR-Bypassing Backdoor. How to Hunt the “Job Seeker” Attack. (A PostMortem) — by CyberDudeBivash

Phase 1: The “HR Vector” (Why Your Training & EDR Fail)

1. The “Training” Bypass (The Lure)

2. The “SEG” Bypass (The “ZIP Trick”)

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

Phase 2: The “Fileless” Kill Chain (From Click to C2 Beacon)

Stage 1: Initial Access (The HR Inbox)

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

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

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

Exploit Chain (Engineering)

Reproduction & Lab Setup (Safe)

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

Mitigation & Hardening (The CISO Mandate)

Audit Validation (Blue-Team)

Recommended by CyberDudeBivash (Partner Links)

CyberDudeBivash Services & Apps

FAQ

Timeline & Credits

References

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Detection & Hunting Playbook (The New SOC Mandate)