Filemaker Pro 13.03 / Advanced 12.04 - Authentication Bypass / Privilege Escalation

Filemaker Login Bypass and Privilege Escalation
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[ADVISORY INFORMATION]

Title:    		Filemaker Login Bypass and Privilege Escalation
Discovery date: 	19/10/2014
Release date:   	19/10/2014
Vendor Homepage: 	www.filemaker.com
Version:		Filemaker Pro 13.0v3 - FileMaker Pro Advanced 12.0v4
Credits:        	Giuseppe D'Amore (http://it.linkedin.com/pub/giuseppe-d-amore/69/37/66b)
 
[VULNERABILITY INFORMATION]

Class:           	Authentication Bypass and Privilege Escalation
Category:		Desktop Application
Severity:		High
CVSS v2 Vector:         7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C			

[AFFECTED PRODUCTS]

This security vulnerability affects:

	* FileMaker Pro 13.0v3 - FileMaker Pro Advanced 12.0v4

[VULNERABILITY DETAILS]

There is a obvious vulnerability of FileMaker that allow access to the local FM-based database file:
On DBEngine dll, there is a function called MatchPasswordData:

	...
	...
	...
	5BB8D53A   C68424 74020000 >MOV BYTE PTR SS:[ESP+274],0
	5BB8D542   FF15 D437D25B    CALL DWORD PTR DS:[<&Support.??1PasswordHash@Draco@@QAE@XZ>]  <-- Compute the password's hash.
	5BB8D548   8B8C24 6C020000  MOV ECX,DWORD PTR SS:[ESP+26C]
	5BB8D54F   5F               POP EDI
	5BB8D550   5E               POP ESI
	5BB8D551   8AC3             MOV AL,BL			<-- if AL is 0 then you are not authenticated else if AL is 1 you are authenticated,
 								    so simply by changing a single bit you are able to bypass the login,
								    also if your username is Admin, you can obtain a privilege escalation and full permissions on DB.
	5BB8D553   64:890D 00000000 MOV DWORD PTR FS:[0],ECX
	5BB8D55A   5B               POP EBX
	5BB8D55B   8BE5             MOV ESP,EBP
	5BB8D55D   5D               POP EBP
	5BB8D55E   C2 0400          RETN 4
	...
	...
	...


it doesn't matter if your desktop or mobile application is developed in a "secure manner", your confidential data on the database can be accessed.

[DISCLOSURE TIME-LINE]

    * 19/10/2014 - Public disclosure and simultaneously initial vendor contact.
 
[DISCLAIMER]

The author is not responsible for the misuse of the information provided in
this security advisory. The advisory is a service to the professional security
community. There are NO WARRANTIES with regard to this information. Any
application or distribution of this information constitutes acceptance AS IS,
at the user's own risk. This information is subject to change without notice.