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CISO Briefing: Chrome’s “Emergency” RCE (CVE-2025-11756): Why This Is Your #1 Enterprise Threat. (A Fleet-Wide Patch & Hunt Guide) — by CyberDudeBivash

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

LinkedIn: ThreatWirecryptobivash.code.blog

CHROME 0-DAY • 0-CLICK RCE • EDR BYPASS • CVE-2025-11756

Situation: This is a CISO-level “stop-everything-and-patch” warning. A CVSS 9.8 Critical Remote Code Execution (RCE) 0-day, CVE-2025-11756, has been found in Google Chrome’s V8 Engine / Safe Browsing component. This flaw is being *actively exploited in the wild* by APTs in “drive-by” attacks.

This is a decision-grade CISO brief. This is not a “simple” bug. It’s the “golden key” that bypasses your perimeter. An employee *visiting a legitimate but compromised website* is all it takes for an attacker to get a foothold. Your EDR is blind to the initial exploit. This is the new TTP for Session Hijacking and Ransomware deployment.

TL;DR — A “God mode” 0-click flaw (CVE-2025-11756) in Chrome is being exploited.

• The Flaw: A Use-After-Free in the V8/Safe Browsing component.
• The Impact: 0-Click RCE. Just *visiting* a website can give an attacker a shell.
• The Kill Chain: 1) “Drive-by” RCE (CVE-2025-11756) -> 2) “Sandbox Escape” (2nd flaw) -> 3) `SYSTEM` Access -> 4) EDR Kill & Ransomware.
• Why EDR Fails: The exploit is *fileless* and *in-memory*. It runs inside the *trusted* `chrome.exe` process.
• THE ACTION: 1) PATCH ALL CHROMIUM BROWSERS NOW (Chrome, Edge, Brave). 2) HUNT for the *post-exploit* TTP: `chrome.exe` spawning `powershell.exe`.

Vulnerability Factbox

CVE	Component	Severity	Exploitability	Patch / Version
CVE-2025-11756	Chrome V8 / Safe Browsing	Critical (9.8)	0-Click RCE (Drive-by)	141.0.7390.107+

Critical 0-Click RCEEDR Bypass TTPFileless / In-MemoryContents

1. Phase 1: The Exploit (Why “0-Click” is a CISO’s Nightmare)
2. Phase 2: The Kill Chain (From “Sandbox” to “SYSTEM”)
3. Exploit Chain (Engineering)
4. Reproduction & Lab Setup (Safe)
5. Detection & Hunting Playbook (The *New* SOC Mandate)
6. Mitigation & Hardening
7. Patch Validation (Blue-Team)
8. Tools We Recommend (Partner Links)
9. CyberDudeBivash Services & Apps
10. FAQ
11. Timeline & Credits
12. References

Phase 1: The Exploit (Why “0-Click” is a CISO’s Nightmare)

To understand why this is a CISO-level crisis, you must understand what “0-Click” means in a browser context.

Your *entire* security awareness training program (phishing, vishing) is based on *stopping a user from doing something stupid*. A 0-Click RCE makes your “human firewall” completely irrelevant.

The attacker needs *no user interaction*. They just need your employee to *visit a compromised website*. This is the “watering hole” attack. The exploit (CVE-2025-11756) is a Use-After-Free (UAF) flaw in the V8 JavaScript engine.

Here’s the CISO-level analogy:

• The V8 engine (the “program”) allocates a piece of memory (a “box”) to store a variable.
• It uses the box and then “frees” it, making it available for other data.
• The Flaw: The engine *forgets* to delete its old “key” to that box.
• An attacker’s malicious JavaScript code then “claims” that *exact same* box.
• The V8 engine, using its old “key,” writes data to the box, thinking it’s still *its* data. But it’s actually overwriting the *attacker’s* data.

By carefully crafting what they put in that “box,” an attacker can use this “overwrite” to hijack the program’s flow. This is Remote Code Execution (RCE). The attacker now has *full control* over the browser’s “renderer” process. They are “in the building,” but locked in a single, sandboxed room.

Phase 2: The Kill Chain (From “Sandbox” to “SYSTEM”)

This is the most critical concept for a CISO. An attacker doesn’t just “use” a V8 exploit. They *chain* it. This is a multi-stage attack.

Stage 1: Initial Access (The “Drive-By” / “Watering Hole”)

The attacker doesn’t send 10 million “spam” emails. They find *one* legitimate website your employees visit (a “watering hole”) and inject their malicious code there. Your employee, just doing their job, visits `compromised-news-site.com`. This is a 0-click “drive-by” attack. The page loads, the exploit runs. No click is needed.

Stage 2: RCE in Sandbox (CVE-2025-11756)

The malicious JavaScript on that site executes. The V8 exploit (CVE-2025-11756) is triggered. The attacker now has an RCE shell *inside* the Chrome sandbox. They can read all the data *in that tab*, but they can’t take over the PC. Yet.

Stage 3: Sandbox Escape (The *Second* Flaw)

This is the “pro-level” move. The attacker *immediately* uses their foothold to exploit a *second* vulnerability. This is a sandbox escape flaw, often a Windows/Linux/macOS kernel vulnerability or a bug in the browser’s IPC (Inter-Process Communication) broker. This second exploit allows their code to “break out” of the sandbox and gain `SYSTEM` or `root` privileges on the host machine.

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

The game is over. The attacker is now `SYSTEM` on your employee’s laptop. They will immediately:

1. Spawn `powershell.exe` from the `chrome.exe` process (a *huge* behavioral red flag).
2. Download their Command & Control (C2) implant (e.g., Cobalt Strike, Metasploit).
3. Use that implant to dump all browser cookies (hijacking *all* of the user’s SaaS sessions).
4. Connect to your corporate VPN and begin lateral movement to find domain controllers and file servers.
5. Deploy ransomware across the enterprise.

Exploit Chain (Engineering)

This is a Memory Corruption flaw in a JIT (Just-In-Time) Compiler.

• Trigger: A “drive-by” 0-click visit to a website hosting the malicious JavaScript.
• Precondition: Unpatched Chrome/Edge/Brave (V8) on Windows, macOS, or Linux.
• Sink (The RCE): A Use-After-Free (UAF) flaw in the V8 JIT compiler or Safe Browsing component.
• Module/Build: `chrome.exe` (Trusted) → `(sandbox escape)` → `powershell.exe` (The “Pivot”)
• Patch Delta: The fix involves *stricter* bounds-checking and memory validation in the V8 C++ code.

Reproduction & Lab Setup (Safe)

DO NOT ATTEMPT. This is a nation-state level 0-day exploit. You cannot “reproduce” this TTP safely. Your *only* defense is to PATCH and HUNT for the *results* of the breach (the IOCs).

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

Your SOC *cannot* hunt on the *browser*. It *must* hunt on the *endpoint* logs. Your 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 `chrome.exe` (or `msedge.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 = ‘chrome.exe’ OR parent_process_name = ‘msedge.exe’ OR parent_process_name = ‘brave.exe’) AND (process_name = ‘powershell.exe’ OR process_name = ‘cmd.exe’ OR process_name = ‘bash’ OR process_name = ‘sh’)
• Hunt TTP 2 (The C2): “Show me all *network connections* from `chrome.exe` to a *newly-registered domain* or *anomalous IP* that is *NOT* the main website’s domain.”
• Hunt TTP 3 (The Session Hijack): This is the *real* goal. SessionShield (our app) is *built* to hunt for this: “Show me all M365 logins where the *session* IP/User-Agent is *different* from the *login* IP/User-Agent.”

The “Noise” vs. “Signal”: Your automated EDR *will* miss this. It sees “trusted” processes. You *must* have a 24/7 human-led MDR team (like ours) that has the *context* to know that `chrome.exe -> powershell.exe` is not “noise,” it’s a *critical breach*.
Explore Our 24/7 MDR Service →

Mitigation & Hardening (The CISO Mandate)

Patching is Step 1. Hardening is how you *survive* the *next* 0-day.

• 1. PATCH NOW (The Mandate): This is the #1 priority. See validation section below. Force-update all Chrome/Edge/Brave browsers in your GPO/MDM *today*.
• 2. Deploy a *Real* EDR: You *must* have a *behavioral* EDR (like Kaspersky EDR) that *can* detect the `chrome.exe -> powershell.exe` TTP.
• 3. Deploy Session Monitoring (The “Alarm”): You *must* assume the token *will* be stolen. SessionShield is the *only* tool that “fingerprints” the session and *kills it* when it’s hijacked.
• 4. Mandate Phish-Proof MFA (FIDO2): The *goal* of this RCE is often *session token theft*. Hardware Keys (FIDO2) *token-bind* the session, making the stolen cookie *useless*.

Patch Validation (Blue-Team)

You must *enforce* this patch across your *entire* fleet.

• GPO (Group Policy): Use the Google Update ADMX templates. Set `Update policy override` to `Allow Updates (recommended)`. Then *force* it: `Invoke-GPUpdate -Computer [ComputerName] -Force`.
• MDM/UEM Query: Run a report on *all* devices in your fleet.
• The Query: “Show me all devices with `chrome.exe` version *less than* `141.0.7390.107`.”
• The Action: Any device that is not patched is *quarantined*. It is *blocked* from accessing *all* corporate resources (VPN, M365) until it is patched.

Is Your Fleet *Already* Breached?
Your EDR is blind. Your ZTNA is compromised. CyberDudeBivash is the leader in Ransomware & Espionage Defense. We are offering a Free 30-Minute Ransomware Readiness Assessment to show you the *exact* gaps in your “Session Hijacking” and “Fileless Malware” 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*. You *must* have a *real* behavioral EDR to *hunt* for the `chrome.exe -> powershell.exe` TTP.Edureka — Incident Response Training
Train your SecOps team *now* on Browser Exploit Hunting and Cloud Log Analysis.TurboVPN
Your BYOD/remote devices *must* be on a trusted, encrypted VPN to prevent other MitM attacks.

Alibaba Cloud (VDI)
This is *how* you build the “Firewall Jails” (Network Segmentation) to contain your BYOD fleet.AliExpress (Hardware Keys)
The *ultimate* fix. A FIDO2 key makes your M365 session *cryptographically bound* to your hardware, making the stolen cookie *useless*.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 stop them. We are the “human-in-the-loop” that your automated defenses are missing.

• SessionShield — Our flagship app. This is the *only* solution designed to *behaviorally* detect and *instantly* kill a hijacked M365/Teams session. It is the “alarm” for your ZTNA policy *after* the 0-day.
• Emergency Incident Response (IR): Our 24/7 team will deploy *today* to hunt your *EDR & Cloud logs* for the TTPs that signal this breach.
• Managed Detection & Response (MDR): Our 24/7 SOC team becomes your “human sensor,” hunting for these behavioral TTPs 24/7.
• Adversary Simulation (Red Team): We will *simulate* this *exact* 0-click-to-session-hijack TTP to prove your ZTNA and EDR are blind.

Get a Demo of SessionShieldBook Your FREE 30-Min AssessmentSubscribe to ThreatWire

FAQ

Q: What is a “0-Click RCE”?
A: It’s a “zero-click” exploit. It means the victim does *nothing*. No click, no download, no “Enable Macros.” The attack executes *automatically* as soon as the target (the browser) *receives* the malicious data (e.g., visits a website). It is the most dangerous class of exploit.

Q: I use Edge/Brave/Vivaldi. Am I safe?
A: NO. This is a vulnerability in Chromium V8, the engine that *all* these browsers use. You are just as vulnerable. You MUST go to `Help > About` and force the update on *all* your Chromium-based browsers.

Q: I forced the update. Am I 100% safe?
A: You are safe from *new* attacks using this flaw. You are *not* safe if an attacker *already* breached you *before* you patched. This is why “Patch” is only Step 1. “Hunt” (Step 2) is *mandatory*. You must call our IR team or your MDR provider to hunt for compromise.

Q: How do I hunt for this?
A: You need a behavioral EDR (like Kaspersky) and an expert MDR team. The hunt query is: “Show me anomalous process chains” (e.g., `chrome.exe -> powershell.exe`) and “Show me all EDR agent service-stop events.”

Timeline & Credits

This 0-Day (CVE-2025-11756) was discovered by an independent security researcher and reported to Google. It was added to the CISA KEV catalog on or around Nov 1, 2025, due to *active exploitation* in the wild.

References

• CISA KEV (Known Exploited Vulnerabilities) Catalog
• Google Threat Analysis Group (TAG)
• CyberDudeBivash: SessionShield – The Session Hijacking Defense

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