IcoFX 2.5.0.0 Buffer Overflow

`Core Security - Corelabs Advisory  
http://corelabs.coresecurity.com/  
  
IcoFX Buffer Overflow Vulnerability  
  
  
1. *Advisory Information*  
  
Title: IcoFX Buffer Overflow Vulnerability  
Advisory ID: CORE-2013-1107  
Advisory URL:  
http://www.coresecurity.com/advisories/icofx-buffer-overflow-vulnerability  
Date published: 2013-12-10  
Date of last update: 2013-12-10  
Vendors contacted: IcoFX Software  
Release mode: User release  
  
  
2. *Vulnerability Information*  
  
Class: Buffer overflow [CWE-119]  
Impact: Code execution  
Remotely Exploitable: No  
Locally Exploitable: Yes  
CVE Name: CVE-2013-4988  
  
  
3. *Vulnerability Description*  
  
IcoFX [1] is prone to a (client side) security vulnerability when  
processing .ICO files. This vulnerability could be exploited by a remote  
attacker to execute arbitrary code on the target machine, by enticing  
the user of IcoFX to open a specially crafted icon file.  
  
  
4. *Vulnerable Packages*  
  
. IcoFX v2.5.0.0 for Windows.  
. Other versions are probably affected too, but they were not checked.  
  
  
5. *Vendor Information, Solutions and Workarounds*  
  
There was no official answer from vendor after several attempts to  
report this vulnerability (see [Sec. 8]). As mitigation action, given  
that this is a client-side vulnerability, avoid to open untrusted ICO  
files. Contact vendor for further information.  
  
  
6. *Credits*  
  
This vulnerability was discovered and researched by Marcos Accossatto  
from Core Exploit Writers Team. The publication of this advisory was  
coordinated by Fernando Miranda from Core Advisories Team.  
  
  
7. *Technical Description / Proof of Concept Code*  
  
Below is shown the result of opening the maliciously crafted file  
'CORE-2013-1107-icofx-poc.ico'[2] on Windows XP SP3 (EN).  
  
The vulnerable function is located in 0x80D9F8. By loading the PoC, the  
loop [0x80DA74, 0x80DA93] fills the buffer and overwrite the Exception  
Handler:  
  
/-----  
0080DA74 8B45 E8 MOV EAX,DWORD PTR SS:[EBP-18]  
0080DA77 03C0 ADD EAX,EAX  
0080DA79 8D94C5 8CF9FFFF LEA EDX,DWORD PTR SS:[EBP+EAX*8-674]  
0080DA80 B9 10000000 MOV ECX,10 ;  
Will copy 16 bytes from file to buffer  
0080DA85 8B45 F8 MOV EAX,DWORD PTR SS:[EBP-8]  
0080DA88 8B18 MOV EBX,DWORD PTR DS:[EAX]  
0080DA8A FF53 0C CALL DWORD PTR DS:[EBX+C]  
0080DA8D FF45 E8 INC DWORD PTR SS:[EBP-18] ;  
Index, will be overwritten with our value in the penultimate loop turn  
0080DA90 FF4D DC DEC DWORD PTR SS:[EBP-24] ;  
Counter, will be overwritten with our value in the penultimate loop turn  
0080DA93 75 DF JNZ SHORT 0080DA74  
0080DA95 0FBF45 F0 MOVSX EAX,WORD PTR SS:[EBP-10]  
-----/  
  
At the 'MOVSX' of 0x80DA95, the CPU registers are as follows:  
  
  
/-----  
EAX 00000010  
ECX 7C80189C kernel32.7C80189C  
EDX 00000010  
EBX 004617F4 IcoFX2.004617F4  
ESP 0012F380  
EBP 0012FA08  
ESI 005B2CBC IcoFX2.005B2CBC  
EDI 02555C80  
EIP 0080DA95 IcoFX2.0080DA95  
C 1 ES 0023 32bit 0(FFFFFFFF)  
P 1 CS 001B 32bit 0(FFFFFFFF)  
A 0 SS 0023 32bit 0(FFFFFFFF)  
Z 1 DS 0023 32bit 0(FFFFFFFF)  
S 0 FS 003B 32bit 7FFDF000(FFF)  
T 0 GS 0000 NULL  
D 0  
O 0 LastErr ERROR_SUCCESS (00000000)  
EFL 00200247 (NO,B,E,BE,NS,PE,GE,LE)  
ST0 empty -??? FFFF 00F300F3 00F300F3  
ST1 empty -??? FFFF 00FE00FE 00FE00FE  
ST2 empty -??? FFFF 00000009 00220065  
ST3 empty -??? FFFF 0000000A 00240069  
ST4 empty 1.2948274137727088000e+16  
ST5 empty 2.5896178900861029000e+16  
ST6 empty 3.2651492439228483000e+16  
ST7 empty 3.1244147623526446000e+16  
3 2 1 0 E S P U O Z D I  
FST 0000 Cond 0 0 0 0 Err 0 0 0 0 0 0 0 0 (GT)  
FCW 1272 Prec NEAR,53 Mask 1 1 0 0 1 0  
-----/  
  
And the stack Exception Handler is overwritten (shellcode starts in  
0x12F3A4):  
  
  
/-----  
0012F380 0012FA10 Pointer to next SEH record  
0012F384 42424242 SE handler  
0012F388 41414141  
0012F38C 41414141  
0012F390 41414141  
0012F394 000502A8  
0012F398 7E4188A6 USER32.GetWindowLongW  
0012F39C 00000000  
0012F3A0 0012F3D8 ASCII "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"...  
0012F3A4 41414141  
-----/  
  
As a result, the normal execution flow can be altered in order to  
execute arbitrary code.  
  
  
8. *Report Timeline*  
  
. 2013-11-11:  
Core Security Technologies attempts to contact the IcoFX team; no reply  
received. Publication date is set for Dec 3rd, 2013.  
  
. 2013-11-14:  
Core attempts to contact vendor.  
  
. 2013-11-26:  
Core attempts to contact vendor.  
  
. 2013-12-03:  
Core attempts to contact vendor.  
  
. 2013-12-03:  
First release date missed.  
  
. 2013-12-10:  
Advisory CORE-2013-1107 published.  
  
  
9. *References*  
  
[1] http://icofx.ro/.  
[2]  
http://www.coresecurity.com/system/files/attachments/2013/12/CORE-2013-1107-icofx-poc.zip  
  
  
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12. *Disclaimer*  
  
The contents of this advisory are copyright (c) 2013 Core Security  
Technologies and (c) 2013 CoreLabs, and are licensed under a Creative  
Commons Attribution Non-Commercial Share-Alike 3.0 (United States)  
License: http://creativecommons.org/licenses/by-nc-sa/3.0/us/  
  
  
13. *PGP/GPG Keys*  
  
This advisory has been signed with the GPG key of Core Security  
Technologies advisories team, which is available for download at  
http://www.coresecurity.com/files/attachments/core_security_advisories.asc.  
  
  
`