Core Security - Corelabs Advisory
http://corelabs.coresecurity.com/
IcoFX Buffer Overflow Vulnerability
PoC: http://www.exploit-db.com/sploits/30208.zip
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
10. *About CoreLabs*
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11. *About Core Security Technologies*
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and demonstrate real-world exposures to their most critical assets. Our
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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.
