Aloaha PDF Suite Buffer Overflow Vulnerability

1. Advisory Information

Title: Aloaha PDF Suite Buffer Overflow Vulnerability
Advisory ID: CORE-2013-0805
Advisory URL: http://www.coresecurity.com/advisories/aloaha-pdf-suite-buffer-overflow-vulnerability
Date published: 2013-08-28
Date of last update: 2013-08-28
Vendors contacted: Aloaha Software
Release mode: User release

2. Vulnerability Information

Class: Buffer overflow [CWE-119]
Impact: Code execution
Remotely Exploitable: Yes
Locally Exploitable: No
CVE Name: CVE-2013-4978

3. Vulnerability Description

Aloaha PDF Suite [1], [2] is prone to a security vulnerability when processing PDF files. This vulnerability could be exploited by a remote attacker to execute arbitrary code on the target machine by enticing Aloaha users to open a specially crafted PDF file.

4. Vulnerable Packages

  • AloahaPDFViewer v5.0.0.7.
  • Older versions are probably affected too, but they were not checked.

5. Vendor Information, Solutions and Workarounds

There was no official answer from Aloaha 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 PDF files. Contact vendor for further information.

6. Credits

This vulnerability was discovered and researched by Marcos Accossatto from CORE Exploit Writers Team.

7. Technical Description / Proof of Concept Code

Below is shown the result of opening the maliciously crafted PDF file [3]:

$+B6BB8  >|>  8B07              |MOV EAX,DWORD PTR DS:[EDI]
$+B6BBA  >|.  C740 14 1E000000  |MOV DWORD PTR DS:[EAX+14],1E    ;  < Exception - Tries to write to 909090A4
$+B6BC1  >|.  8B5424 04         |MOV EDX,DWORD PTR SS:[ESP+4]
$+B6BC5  >|.  8950 18           |MOV DWORD PTR DS:[EAX+18],EDX
$+B6BC8  >|.  8BC7              |MOV EAX,EDI
$+B6BCA  >|.  8B10              |MOV EDX,DWORD PTR DS:[EAX]    

At that time, the registers EDX, EBX, EBP and EDI points to the shellcode; the EAX register contains the first DWORD of our shellcode:

EAX 90909090
ECX 000007B4
EDX 0012DD44 ASCII "DDDDDDDDDDDDDD..."
EBX 051ACFF1 ASCII "DDDDDDDDDDDDDD..."
ESP 0012D9EC
EBP 0012DC54 ASCII "DDDDDDDDDDDDDD..."
ESI 000002F0
EDI 0012DB78
EIP 03727BBA
C 0  ES 0023 32bit 0(FFFFFFFF)
P 1  CS 001B 32bit 0(FFFFFFFF)
A 0  SS 0023 32bit 0(FFFFFFFF)
Z 0  DS 0023 32bit 0(FFFFFFFF)
S 0  FS 003B 32bit 7FFDF000(FFF)
T 0  GS 0000 NULL
D 0
O 0  LastErr ERROR_NOT_ENOUGH_MEMORY (00000008)
EFL 00000206 (NO,NB,NE,A,NS,PE,GE,G)
ST0 empty 16312.144994243513790
ST1 empty 3869.8214873218676080
ST2 empty -0.0
ST3 empty -0.0
ST4 empty 1.0000000000000000000
ST5 empty 4.3980465111040000000e+12
ST6 empty 5.3078580233502760000e+15
ST7 empty 5.0609752291423027300e+17
               3 2 1 0      E S P U O Z D I
FST 0020  Cond 0 0 0 0  Err 0 0 1 0 0 0 0 0  (GT)
FCW 037F  Prec NEAR,64  Mask    1 1 1 1 1 1    

The stack's exception handler is overwritten with:

0012D9EC   FFFFF94D
0012D9F0   0000000A
  ....       ....
0012DB5C   0EDDE2F1
0012DB60   909006EB  Pointer to next SEH record
0012DB64   1106D8A0  SE handler    

In the address 1106D8A0 of AloahaTranslator.dll we have:

   
1106D8A0   .  83C4 14   ADD ESP,14
1106D8A3   .  C3        RETN

and the stack:

$ ==>    > 7C9032A8  RETURN to ntdll.7C9032A8
$+4      > 0012D704
$+8      > 0012DB60
$+C      > 0012D720
$+10     > 0012D6D8
$+14     > 0012DB60  Pointer to next SEH record

So, the RETN of 1106D8A3 will jump to 12DB60 (the stack) where our shellcode is located:

0012DB60   EB 06             JMP SHORT 0012DB68
0012DB62   90                NOP
0012DB63   90                NOP
0012DB64   A0 D8061190       MOV AL,BYTE PTR DS:[901106D8]
0012DB69   90                NOP    

which means the normal execution flow can be altered in order to execute arbitrary code.

8. Report Timeline

  • 2013-08-06: Core Security Technologies notifies the Aloaha team of the vulnerability. Publication date is set for Aug 27th, 2013.
  • 2013-08-06: Vendor asks for a report with technical information.
  • 2013-08-06: Technical details and proof of concept sent to Aloaha team.
  • 2013-08-12: Core asks for a status update and notifies the advisory publication was scheduled for Aug 27th. No reply received.
  • 2013-08-20: Core attempts to contact vendor.
  • 2013-08-26: Core attempts to contact vendor.
  • 2013-08-27: Release date missed.
  • 2013-08-28: After 3 attempts to contact vendor, the advisory CORE-2013-0805 is published as 'user release'.

9. References

[1] http://www.aloaha.com.
[2] http://www.aloaha.com/wi-software-en/aloaha-pdf-suite-freeware.php.
[3] http://www.coresecurity.com/system/files/attachments/2013/08/CORE-2013-0805-aloaha-poc-94238712635.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

Core Security Technologies enables organizations to get ahead of threats with security test and measurement solutions that continuously identify and demonstrate real-world exposures to their most critical assets. Our customers can gain real visibility into their security standing, real validation of their security controls, and real metrics to more effectively secure their organizations.

Core Security's software solutions build on over a decade of trusted research and leading-edge threat expertise from the company's Security Consulting Services, CoreLabs and Engineering groups. Core Security Technologies can be reached at +1 (617) 399-6980 or on the Web at: http://www.coresecurity.com.

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.

Published Date: 
Tuesday, August 27, 2013
Last Updated: 
Tuesday, August 27, 2013 - 6:00pm
Locally Exploitable: 
no
Remotely Exploitable: 
no
CVE Name: 
CVE-2013-4978
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