IcoFX Buffer Overflow Vulnerability

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
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

CoreLabs, the research center of Core Security Technologies, is charged with anticipating the future needs and requirements for information security technologies. We conduct our research in several important areas of computer security including system vulnerabilities, cyber attack planning and simulation, source code auditing, and cryptography. Our results include problem formalization, identification of vulnerabilities, novel solutions and prototypes for new technologies. CoreLabs regularly publishes security advisories, technical papers, project information and shared software tools for public use at: http://corelabs.coresecurity.com.

11. About Core Security Technologies

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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.