exploit the possibilities
Home Files News &[SERVICES_TAB]About Contact Add New

Microsoft Edge Chakra Incorrect Parse

Microsoft Edge Chakra Incorrect Parse
Posted Sep 22, 2017
Authored by Google Security Research, lokihardt

Microsoft Edge Charka incorrectly parses object patterns.

tags | exploit
advisories | CVE-2017-8729
SHA-256 | 861d591b479ea3ed6c0ad8fd09bf8f8400adee9fdab27742f1cf3812afe1c4dc

Microsoft Edge Chakra Incorrect Parse

Change Mirror Download
Microsoft Edge: Chakra incorrectly parses object patterns 

CVE-2017-8729


When the Chakra's parser meets "{", at first, Chakra treats it as an object literal without distinguishing whether it will be an object literal(i.e., {a: 0x1234}) or an object pattern(i.e., {a} = {a: 1234}). After finishing to parse it using "Parser::ParseTerm", if it's an object pattern, Chakra converts it to an object pattern using the "ConvertObjectToObjectPattern" method.

The problem is that "Parser::ParseTerm" also parses ".", etc. using "ParsePostfixOperators" without proper checks. As a result, an invalid syntax(i.e., {b = 0x1111...}.c) can be parsed and "ConvertObjectToObjectPattern" will fail to convert it to an object pattern.

In the following PoC, "ConvertObjectToObjectPattern" skips "{b = 0x1111...}.c". So the object literal will have incorrect members(b = 0x1111, c = 0x2222), this leads to type confusion(Chakra will think "c" is a setter and try to call it).

PoC:
function f() {
({
a: {
b = 0x1111,
c = 0x2222,
}.c = 0x3333
} = {});
}

f();


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

Login or Register to add favorites

File Archive:

May 2024

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    May 1st
    44 Files
  • 2
    May 2nd
    5 Files
  • 3
    May 3rd
    11 Files
  • 4
    May 4th
    0 Files
  • 5
    May 5th
    0 Files
  • 6
    May 6th
    28 Files
  • 7
    May 7th
    3 Files
  • 8
    May 8th
    4 Files
  • 9
    May 9th
    54 Files
  • 10
    May 10th
    12 Files
  • 11
    May 11th
    0 Files
  • 12
    May 12th
    0 Files
  • 13
    May 13th
    17 Files
  • 14
    May 14th
    11 Files
  • 15
    May 15th
    17 Files
  • 16
    May 16th
    13 Files
  • 17
    May 17th
    22 Files
  • 18
    May 18th
    0 Files
  • 19
    May 19th
    0 Files
  • 20
    May 20th
    17 Files
  • 21
    May 21st
    18 Files
  • 22
    May 22nd
    7 Files
  • 23
    May 23rd
    111 Files
  • 24
    May 24th
    27 Files
  • 25
    May 25th
    0 Files
  • 26
    May 26th
    0 Files
  • 27
    May 27th
    6 Files
  • 28
    May 28th
    12 Files
  • 29
    May 29th
    0 Files
  • 30
    May 30th
    0 Files
  • 31
    May 31st
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2022 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close